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What are the benefits of applying greenhouse shading products?

Sudlac shading products give greenhouse growers of flowers and vegetables the ability to increase and extend production during periods of warm temperatures and high light levels.

High temperatures and high light levels, especially during the summer can have negative effects on ornamental and vegetable crops produced in protected structures, including greenhouses. An economical way for growers to reduce light and temperature levels is by applying shading products to greenhouse glazing materials.

“The application of shading products is related to maximizing the production capacity of the greenhouse,” said Ruben Lensing, area export manager at Sudlac. “Shading products can allow a grower to optimize the climate in the greenhouse, therefore increasing yields without having to invest in more structures. Warm temperatures can impact crop yields, whether a grower is producing flowers or vegetables. If it is too warm, a grower can bring down the temperature by applying a shading product, which can improve crop yields as well as extending production during warmer periods.

“Typically in July and August the greenhouse environment is much too warm in many parts of the U.S. During this time if the grower doesn’t reduce the temperature there will be some crop loss. If the temperature is reduced with shading, a grower may not be able to produce as much as in the spring, but the crop will survive and produce during these warmer months as well as into September and October. The use of shading is all about increasing crop productivity and extending the time of production.”

 

Application for all types of crops

Lensing said all types of growers are using Sudlac shading products.

“Sudlac products are used on all types of greenhouse crops including cut flowers, potted plants and vegetables,” he said. “Sudlac products are also now being used on the production of the newest greenhouse crop—cannabis. “I am visiting some greenhouse growers in the U.S. who are looking to change their crop from flowers to cannabis.

“Since there are more vegetables grown worldwide in greenhouse and protected structures, Sudlac products are used more with vegetable production. That is only because of the size of the worldwide vegetable market.”

 

 

Ruben Lensing, area export manager at Sudlac, said growers can lower greenhouse temperatures by applying a shading product, which can improve crop yields as well as extending production during warmer periods.

 

Lensing said Sudlac products are being used to increase production of both flowers and vegetables.

“With cut flowers, such as freesias, alstroemeria and gerbera, there are more shoots produced,” he said. “This means more flowers are produced per plant. Also, there is less fading of the flower color so the color is more intense.”

For potted plants, Lensing said certain kinds of shading can create more compact plants.

“Using a shade product can lower temperature at high light levels,” he said. “This allows a grower to produce a sturdy compact plant that is higher quality. This may also allow a grower to eliminate or reduce the amount of plant growth regulators that are needed. Applying shade can lower production costs and increase a grower’s return on investment.”

Lensing said the benefit of applying shade for vegetables like tomatoes, peppers and cucumbers, can result in more fruit produced per plant. Also, with some crops the fruit are also heavier.

“Applying a shade product translates to more flowers and fruit per plant which means a higher return for the grower,” he said.

 

Different products for different needs

Sudlac offers six different products for the U.S. market, including three shading products, two light diffusing coatings and one shade removing cleaner. Sudlac shading products can be used on all types of glazing material, including polyethylene, rigid materials including acrylic and polycarbonate, and glass.

 

Eclipse LD

Eclipse LD was the first Sudlac product sold in the United States and is the most widely sold product. LD stands for long duration. It is a protective coating against heat and light.

“When Eclipse LD is applied to the greenhouse it lowers the temperature and reduces the amount of light entering the greenhouse,” Lensing said. “Since Eclipse LD lowers the temperature when it is applied on where a greenhouse is located in the U.S. If the greenhouse is in the southern U.S., it might be applied as early as the end of February or beginning of March. In a more northern climate like Minnesota, Eclipse LD probably would be applied in April. Eclipse LD should be taken off when natural light levels decline, which is usually from September to November in most of the U.S. depending on location. It depends on where the greenhouse is located and climate conditions.”

 

Transpar

Transpar is also a removable protective coating that maintains photosynthetically active radiation (PAR) light levels.

“Transpar is a coating that reflects infrared radiation, which is the light that produces the heat in the greenhouse,” Lensing said. “The PAR light is allowed into the greenhouse.”

 

Warm temperatures can impact crop yields, whether a grower is producing flowers or vegetables.

 

 

Optifuse

Optifuse is a removable coating that lets all the light into the greenhouse, but spreads the light.

“Optifuse diffuses the light,” Lensing said. “It spreads the light in the greenhouse so plants won’t burn. This is very important for flowers, lettuce and other vegetables.

“The advantage of using Optifuse is to allow as much light into the greenhouse as possible. Optifuse can be used in dark areas where there isn’t a lot of sunlight. When the light comes into the greenhouse all of it comes in, but it is spread throughout the greenhouse.

“There is one application exception with Optifuse shading product,” Lensing said. “Optifuse cannot be used on polyethylene film, but it can be used on every other type of glazing.

 

Optifuse IR

Optifuse IR is combines and properties of Optifuse and Transpar.

“Optifuse IR lowers the temperature by reflecting infrared radiation,” Lensing said. “It diffuses the light into the greenhouse like Optifuse and lowers the temperature like Transpar.”

 

Sombrero

Sombrero is an economical whitewash liquid. Like Eclipse it lowers the temperature. It is commonly used in warmer climates including southern California, Florida and Texas. Sombrero is removed by rain or water and no special product has to be applied to remove it from the greenhouse glazing.

 

Topclear

Topclear is a shade removing product used to take off Eclipse LD, Transpar, Optifuse and Optifuse IR.

“It is important to use Topclear to remove these shading compounds,” Lensing said. “In most parts of the U.S. from September through November all of the shade should be removed from the greenhouse so that the glazing is completely clean to optimize plant production during the winter months.”

 


David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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Over $17 million available for organic research funding

USDA’s National Institute for Food and Agriculture (NIFA) has released its Request for Applications (RFA) for the Organic Agriculture Research and Extension Initiative (OREI). OREI grants provide crucial support to the organic industry by funding research, education, and extension projects to improve and advance organic agriculture.

A total of $17.6 million is expected to be available for projects designated in OREI’s eight legislatively defined purposes (including the biological, physical and social sciences) in fiscal year (FY) 2018. All applications for consideration are to be submitted by March 1, 2018.

NIFA has identified nine priority areas for FY 2018, including a new priority focused specifically on policy. This new priority area is intended for projects that “identify marketing, policy, and other socioeconomic barriers to the expansion of organic agriculture in the United States and develop strategies to address them. Lobbying and advocacy activities do not fit under this priority.”

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What’s the future of conventional agriculture? Does it include vertical farming?

Leading Japanese indoor ag tech companies to visit the heart of U.S. agricultural research and biotechnology community to attend controlled environment networking event.

If you are involved with the vertical farming or indoor agriculture industries, then you should plan on attending Ag Tech Worlds Collide. Scheduled for Feb. 21, 2018, at North Carolina State University, this event will tackle the big questions currently being addressed in the vertical farming and indoor agriculture industries worldwide.

Urban Ag News and the Japan Plant Factory Association in coordination with the Japanese Ministry of Economy, Trade and Industry are pleased to announce this joint networking event with U.S.-based agricultural organizations and operations. Participating Japanese organizations/companies include: Japan Plant Factory Association, Keystone Technology Inc., Shinnippou 808 Factory, Nihon Advanced Agri Corp., ESPEC MIC Corp. and MIRAI.

 

Presentations focus on CEA impact

Key presentations at this controlled environment agriculture (CEA) event will be made by Dr. Chieri Kubota, professor of controlled environment agriculture at The Ohio State University, and Dr. Ricardo Hernandez, assistant professor in the Department of Horticultural Sciences at North Carolina State University.

Dr. Kubota’s presentation will discuss “Optimizing input and output in controlled environment agriculture.” Dr. Kubota received a PhD. in horticultural engineering and M.S. in horticultural science from Chiba University in Japan. She worked for six years as a faculty member at Chiba University, 16 years in the School of Plant Sciences at the University of Arizona and recently joined the faculty at The Ohio State University. At Chiba University Dr. Kubota studied under and worked with Dr. Toyoki Kozai, one of the most published and greatest minds in indoor agriculture.

Dr. Kubota’s research program focuses on the development of science-based CEA technologies. She has been very active in interdisciplinary collaborations contributing to horticultural crop production under controlled environments. Her research includes value-added CEA crop production, vegetable grafting, hydroponic strawberry production and CEA LED lighting applications.

Dr. Hernandez will discuss “Using vertical farming/indoor ag to support traditional farming. He is a faculty member in the Department of Horticultural Sciences in the area of horticultural energy at North Carolina State University. He has a B.S. in agronomy–crop consulting from New Mexico State University. His M.S. is in entomology–biological control from Texas A&M University. His PhD. is in plant sciences–plant physiology from the University of Arizona. He has a doctoral minor in entrepreneurship from the McGuire Center for Entrepreneurship, Eller School of Business and a minor in ag and biosystems engineering from the University of Arizona.

Dr. Hernandez’s research is focused on making CEA tools and techniques an integral part of sustainable agriculture and horticulture.

 

Event registration, location specifics

Ag Tech Worlds Collide will be held in the York Auditorium of the JC Raulston Arboretum in Raleigh, N.C. Entry to this event is $25 and includes morning coffee service and lunch. Attendance is limited and the event will sell out quickly. Click here to register.

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Dissolved oxygen improves plant growth, reduces crop time

Incorporating dissolved oxygen into hydroponic production systems during warmer temperatures can help improve plant growth and reduce crop time.

Trying to grow hydroponic crops like leafy greens can be a real challenge during warmer times of the year. Growers have few options to lower temperatures, including cooling the greenhouse and/or water temperature. Another production technique that is being used by hydroponic growers in the United States and Australia is to introduce dissolved oxygen into the fertilizer tank solution.

“We’ve heard anecdotal reports that increasing dissolved oxygen levels can help prevent some root diseases like Pythium and other root rots,” said Tyler Baras, special projects manager at Hort Americas in Bedford, Texas. “We’ve also heard that increasing dissolved oxygen can possibly improve nutrient uptake and improve overall growth. Another possible benefit with using dissolved oxygen is reducing tip burn on leafy greens.

“These are some of the main issues with growing in warm climates like Texas during the summer. With an increase in water temperature comes a higher disease pressure and chances for tip burn. This has occurred in both nutrient film technique and deep water culture systems.”

Hort Americas conducted trials growing butterhead lettuce, basil and arugula in deep water culture systems at three different levels of dissolved oxygen.
Photos courtesy of Tyler Baras

The optimum water temperature for lettuce is between 65ºF-70ºF. For basil the optimum water temperature is around 75ºF.

Baras said most of the references he has read for adding dissolved oxygen suggest incorporating 4-10 parts per million for leafy greens.

“Most growers that I know are adding between 6-7.5 ppm for leafy greens,” he said. “When growers start to go beyond that rate to reach a higher level they have to use something like compressed oxygen or ozone. These are the main two methods, which are more expensive, for achieving a higher dissolved oxygen rate. Most growers I know are using a less expensive Venturi system or an air pump with air stones to add dissolved oxygen.”

 

Trialing different levels of dissolved oxygen

Baras has been studying the impact different dissolved oxygen levels can have on butterhead lettuce, basil and arugula grown in deep water culture systems. He set up deep water culture systems with three different levels of dissolved oxygen: 2 ppm, 7.5 ppm and 29 ppm.

“We have been tracking growth and how it affects the morphology of the plants,” he said. “The 2 ppm dissolved oxygen rate is what we were able to achieve without doing any type of aeration. This was our control.”

In another system Baras used a Venturi attachment to a small submersible pump that drew in atmospheric air.

“The highest rate of dissolved oxygen that we could achieve using atmospheric air was a maximum of 8.5 ppm,” he said. “The rate hovers between 7.5 to 8.2 ppm, with it usually averaging 7.5 ppm.”

The third system is a high rate of dissolved oxygen that uses compressed oxygen tanks to deliver 29 ppm.

“This system uses nanobubble technology,” he said. “We were using a prototype device that forces oxygen into a solution in really small bubbles so that the oxygen stays in suspension longer instead of falling out. The lowest rate that we could set was 29 ppm. This level of dissolved oxygen is much higher than what most leafy greens growers are targeting.

“A lot of the flowering crop and cannabis growers who are incorporating dissolved oxygen are actually targeting these higher rates. These growers are achieving 20-40 ppm dissolved oxygen. The flower and cannabis crops tend to prefer to be grown on the dry side. With this type of nanobubble dissolved oxygen technology it opens up this production method to crops beyond leafy greens.”

 

Some dramatic results

Baras said he has seen some dramatic effects on plant growth with higher dissolved oxygen rates. At the beginning of the trials during the first month the water temperature in the fertilizer tanks was 80ºF. During the second month the water temperature was between 75ºF-80ºF.

“At 2 ppm the arugula plants were severely stunted and were unsalable,” he said. “At this low rate there were also some severe nutrient deficiencies. At 7.5 ppm the arugula looked normal with slight deficiencies. There weren’t any nutrient issues at the 29 ppm rate and the plants almost doubled in size.”

Baras said even at the low rate of 2 ppm some crops could still be marketable.

“The basil and butterhead lettuce could still pass as marketable at the low 2 ppm rate,” he said. “The plants were very small and it would take several more weeks of production to reach the target weights we were aiming for. At the 7.5 ppm dissolved oxygen rate the plants had fairly normal growth as to what we are used to seeing.

For butterhead lettuce at the 2 ppm rate the heads were smaller and compact. The core of the heads were tighter, but actually had a good shape. At the 7.5 ppm and 29 ppm rates, the heads had similar shapes.

Butterhead lettuce (left to right) grown in 29 ppm, 7.5 ppm and 2 ppm of dissolved oxygen.

For the basil there was an increase in height as the dissolved oxygen level increased. Overall the plant height and size increased at higher dissolved oxygen rates.

“At the 29 ppm rate, the plants looked like the plants at the 7.5 ppm rate, but they were about a week ahead,” Baras said. “Both of these rates produced plants with healthy looking morphology, but the plants receiving 29 ppm dissolved oxygen developed faster. On average all of the crops grown with 29 ppm were at least a week faster to finish to a marketable size.”

 

Differences in root growth

Baras said the roots for the crops in the three rates of dissolved oxygen had different growth patterns.

“The roots in the 2 ppm dissolved oxygen systems were very short and stubby and almost seemed to be retreating from the water,” he said. “The roots remained mostly in the stone wool rooting cubes.”

At the 7.5 ppm dissolved oxygen rate the roots were long and had a lot of lateral branching. Baras said they looked like standard hydroponic roots.

“At the high 29 ppm rate the roots actually had less lateral branching, but they were really white, long and thick,” he said. “But there was less lateral branching. It almost seemed like since there was so much oxygen in the water the plants didn’t need to have as much lateral branching.”

 

Arugula (left to right) grown in 29 ppm, 7.5 ppm and 2 ppm of dissolved oxygen.

Even though there were differences in the root morphology, there was no significant difference in the root weight for all three dissolved oxygen levels. The average root weight for both the 7.5 ppm and 29 ppm rates was 0.8 ounces. The root weight for the 2 ppm rate was about 0.7 ounces.


For more: Hort Americas, (469) 532-2383; info@hortamericas.com; https://hortamericas.com.

David Kuack is a freelance writer in Fort Worth, Texas; dkuack@gmail.com.

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Nanobubbler generator delivers dissolved oxygen for improved plant growth

Hort Americas is excited to announce that it has been appointed the exclusive distributor of the Moleaer Inc. nanoBoost Nanobubble Generator. The generator delivers a supplementary source of dissolved oxygen that can significantly increase plant growth, improve size uniformity, reduce stress and prevent root diseases under extreme production conditions. It is ideally suited for horticultural applications including hydroponics, greenhouse irrigation and pond management.

 

Real-world application

Hort Americas installed the 50-gallons-per-minute (GPM) nanoBoost in in its hydroponics demonstration greenhouse in Dallas, Texas, to improve the production of leafy greens and culinary herbs during the summer months when warm summer temperatures make production more difficult.

“Our thought was that if we enhance and maintain higher dissolved oxygen levels, we should be able to improve crop health and ultimately improve yield,” said Chris Higgins, general manager at Hort Americas. “We observed dissolved oxygen levels of 29 parts per million in water temperatures of roughly 90ºF. Not only did we achieve our highest level of dissolved oxygen, but our crop yields increased between 20 and 50 percent.”

 

Improving nutrient uptake and plant transpiration

The self-cleaning nanoBoost Nanobubble generator, which has no moving parts, produces oxygen-enriched nanobubbles that efficiently oxygenate an entire body of water and provides a reserve of oxygen encapsulated within the bubbles.

The generator delivers billions of nanobubbles with 200-times the inter-facial surface area when compared to micro bubbles, making them far superior in transporting valuable oxygen to the plants’ root system. The surface of the nanobubbles is negatively charged, attracting nutrient salts and enhancing nutrient uptake. Nanobubbles also increase the mobility of water molecules, potentially improving plant transpiration.

The generator is available in various flow rates and is fully encased in a durable, NEMA4-rated weather-tolerant PVC shell. The unit is self-cleaning and features plug-and-play installation with no moving parts, thus ensuring long-lasting durability with minimal maintenance. The generator can be configured with an integrated pump or retrofitted with a customer’s existing pump to maximize energy efficiency.

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New York City Council passes urban agriculture bill

New York City Council has passed legislation that requires the Department of City Planning to develop a comprehensive urban agriculture plan that addresses land use policy and other issues to promote the expansion of urban agriculture in the city. The department would be required to deliver this plan to the mayor and the speaker of the council by July 1, 2018.

The website aims to promote the expansion of urban agriculture in the city. The Department of City Planning, the Department of Small Business Services and the Department of Parks and Recreation would prepare content for the website. Agencies responsible for the construction and maintenance of the website would be required to issue a review of the website’s efficacy to the City Council by January 1, 2019.

Some of the issues that the urban agriculture plan would address include: cataloguing existing and potential urban agriculture spaces, classification and prioritization of urban agriculture uses, potential land use policies to promote the expansion of agricultural uses in the city, an analysis of those portions of the zoning resolution, building code, and fire code that merit reconsideration to promote urban agriculture, expanding the availability of healthy food in low-income neighborhoods, the integration of urban agriculture into the city’s conservation and resiliency plans, youth development and education with regard to local food production; direct and indirect job creation and impacts from urban agriculture production and the feasibility of creating an office of urban agriculture.

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Moleaer™ Launches nanoBoost™, the Most Efficient Oxygen Delivery Mechanism for Commercial Greenhouses

Moleaer announces commercial partnership with Hort Americas

LOS ANGELES

Moleaer Inc., the leading manufacturer of industrial scale nanobubble generators, expands its innovative product line with the new nanoBoost Nanobubble Generator, ideally suited for applications such as hydroponics, pond management, and irrigation.

Moleaer Inc., the leading manufacturer of industrial scale nanobubble generators, expands its innovative product line with the new nanoBoost Nanobubble Generator, ideally suited for applications such as hydroponics, pond management, and irrigation (PRNewsfoto/H2C Group)

Like the existing Moleaer industrial XTB Nanobubble Generator, the compact nanoBoost is a cost-effective and simple-to-install solution to deliver a supplementary source of oxygen-enriched nanobubbles that remain in suspension longer than conventional micro bubbles, efficiently oxygenating the entire body of water and providing a reserve of oxygen encapsulated within the bubbles.

One of the prime beneficiaries of the nanoBoost are commercial greenhouses.  Moleaer’s nanoBoost has been proven to significantly increase plant growth, improve size uniformity, reduce stress and prevent root disease under the most extreme conditions. It delivers billions of nanobubbles with 200-times the inter-facial surface area when compared to micro bubbles, making them far superior in transporting valuable oxygen to a plant’s root system. In addition, the surface of the nanobubbles is negatively charged, attracting nutrient salts and enhancing nutrient uptake. Nanobubbles also increase the mobility of water molecules, potentially improving plant transpiration.

“We installed the 50-GPM nanoBoost in our Dallas-based hydroponics demonstration greenhouse in order to improve production of leafy greens and culinary herbs during the most difficult production season.  Our thought was that if we enhance and maintained higher dissolved oxygen levels, we should be able to improve crop health and ultimately improve yield,” said Chris Higgins, General Manager of Hort Americas.  “We observed DO levels of 29 ppm in water temperatures of roughly 90 degrees Fahrenheit. Not only did we achieve our highest level of DO, but our crop yields increased between 20 and 50%.”

Moleaer is also pleased to announce that it is collaborating with Hort Americas to commercialize Moleaer’s nanobubble generators within the hydroponics industry.  “We are excited to work with Chris and his team at Hort Americas to accelerate the commercialization of our nanobubble technology,” said Nick Dyner, CEO of Moleaer.  “Hort Americas brings a wealth of knowledge in helping growers utilize best-in-class technology to optimize their growing operations, and we are confident that our nanobubble technology will provide growers a new solution to significantly increase yields within their existing facility.”

The nanoBoost is available in various flow rates and are fully encased in a durable, NEMA4-rated weather-tolerant PVC shell. The unit is self-cleaning and features plug-and-play installation with no moving parts, thus ensuring long-lasting durability with minimal maintenance. The generator can be configured with an integrated pump or retrofitted with a customer’s existing pump to maximize energy efficiency.

 

For more information about Moleaer Inc., visit http://www.moleaer.com

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What are the optimum nutrient levels for hydroponic edible crops?

Trials with organic and conventional fertilizers in hydroponic production systems are showing it’s possible to produce edible crops at much lower nutrient levels.

How much different is it growing edible crops organically than it is with conventional production inputs? Hort Americas special projects manager Tyler Baras is studying the differences in trying to grow organically versus using conventional production methods.

Baras has been doing organic production research in a 12,000-square-foot greenhouse in Dallas, Texas, using four deep water culture ponds and a nutrient film technique system. The ponds measure 4-foot by 8-foot and are 10 inches deep. Baras said the ponds are smaller than what would be found in many commercial greenhouse operations, but said the pond size is common in vertical farm setups. Baras has been trialing commercial organic fertilizers including Pre-Empt and an experimental organic fertilizer. The organic fertilizers are being compared with crops grown with Hort Americas 9-7-37 hydroponic fertilizer with calcium nitrate and magnesium sulfate. All of the production systems have also been incorporated with the commercial microbial inoculant TerraBella. Crops being grown in the production systems include Italian basil, green butterhead and red butterhead lettuce.

Trials in Hort Americas demonstration greenhouse are comparing the growth of butterhead lettuce and Italian basil using organic and conventional fertilizers in hydroponic production systems.
Photos courtesy of Tyler Baras

Rethinking optimum nutrient levels

Baras said the deep water culture production results he has gotten with Pre-Empt organic fertilizer have been comparable to the crops grown with the conventional Hort Americas hydroponic fertilizer.

“With Pre-Empt we have been able to match the growth rates of the conventional salt fertilizer,” Baras said. “As a result of the growth rates we have gotten with the organic fertilizer, we have started to question the nutrient recipes that have been recommended for hydroponic edible crop production. Many of the traditional recipes for hydroponic production have a target level of 200 parts per million nitrogen. But we are seeing the same growth rates in the organic fertilizer ponds with 10 ppm nitrogen as the 200 ppm nitrogen conventional fertilizer pond.”

Baras said the electrical conductivity level in the organic fertilizer ponds has been as a low as 0.5 compared to 2.5 in the conventional fertilizer pond and the crops are coming out nearly identical in terms of production time and plant weight.

One difference between the organic- and conventional-grown crops is the time in propagation.

“The crops are finishing at the same time from transplant to harvest time, but we are keeping the plants an extra week in the seedling stage for the organic fertilizer,” Baras said. “We are running the seedlings for two weeks with the conventional fertilizer and about three weeks with the organic fertilizers.

“The organic plugs are started a week earlier, but they are transplanted on the same day as the conventional plugs. We want the roots coming out of the side of the plugs before we transplant them into the ponds. The seedlings are fairly similar in size when they are transplanted into the ponds.”

Plugs grown in organic substrates and fed with an organic fertilizer remain on the propagation bench one week longer than plugs receiving conventional fertilizer to ensure good root growth.

Once the organic and conventional plugs are placed into the ponds, they both spend the same amount of time there until the crops finish.

“The plants are coming out of the ponds with nearly identical weights,” Baras said. “Overall the seed to harvest time is faster with the conventional fertilizer, but that it is because we are able to transplant the plugs into the pond faster because the roots are coming out of the plugs sooner.”

Baras said the plants grown with the organic fertilizers have also shown they can be grown with lower levels of other nutrients. For example, with the conventional fertilizer the nutrient solution may contain 200 ppm potassium and the level is only 12 ppm with the organic fertilizers.

“Aquaponic growers have seen similar situations,” he said. “Some aquaponic growers may be running an EC of 0.7 with a relatively low nutrient level, but they are still seeing good growth.

We are seeing that as well with the organic fertilizers. There are low nutrient levels in the solution, but the crops are coming out the same and the leaf tissue analysis is nearly the same as well.

“For our trials the macronutrient uptake for the plants, even when they are grown in a low fertilizer concentration like 0.5 EC, they are still able to pull what they need out of the solution. Leaf sample analyses of butterhead lettuce and Italian basil grown in 0.5 EC organic fertilizer vs. 2.5 EC conventional fertilizer, most of the macronutrient levels in the leaves are very similar. It appears the plants are doing a good job of regulating the nutrient uptake to get what they need.”

 

Aging fertilizer solutions

Baras said letting the organic fertilizer solutions age in the ponds may have an impact on the availability of nutrients for some crops. The aging of the fertilizer solutions also has an impact on increasing the microbial population.

“We have definitely seen some differences in plant growth,” he said. “Our first crops of butterhead lettuce and basil did very well with Pre-Empt organic fertilizer. However, one of the other organic fertilizers we trialed grew a quality first crop of lettuce, but not the best looking basil. As we continued the trial with our second and third crops, the basil grown with the other organic fertilizer started doing much better. It appears the organic solutions in the ponds may need to age until the nutrients reach adequate levels.

“This is what we were seeing in a 9-month old Pre-Empt pond vs. a 2-month old Pre-Empt pond. A lot of nutrients have accumulated in the 9-month pond and are approaching the recommended nutrient levels that would be found in a conventional fertilizer system. Organic fertilizers like Pre-Empt don’t have a lot of magnesium in them. However, when the fertilizer is run in a pond system for 9 months the magnesium level rises and approaches what would be considered a conventional fertilizer target level for magnesium.”

Aging of the fertilizer solution also has had an impact on the root growth of the crops.

“When we compare how the roots look visually in the 9-month solution vs. the 2-month solution, the roots in the 9-month solution look much healthier,”Baras said. “The roots are very white, are longer and look really healthy and well-developed. There are also more roots on plants in the 9-month system.

“The root color is also significantly different. In the 2-month solution the roots look healthy, but there is some browning. They don’t have that crisp white look.”

 

Aging of the fertilizer solution can impact root growth. Plants (left) in a 9-month old organic fertilizer solution had more roots that looked healthy and well-developed compared to the root system of plants in a 2-month old organic fertilizer solution.

Rethinking optimum pH levels

Baras said he has been able to produce healthy crops in a pH range from as low as 4 up to 6.5.

“For hydroponic leafy greens the recommended pH ranges from 5.5 to 6.5,” he said. “We have basil and butterhead lettuce growing very well in organic systems at a pH of 4. On the other side of the pH range, I’ve heard of aquaponic growers growing these crops at a pH up to 7 without any problems. Based on our trial results some of the conventional recommendations for hydroponics for both pH and nutrient levels might need to be revisited.

“One of the biggest issues I see with hydroponic growers is overcompensating. For instance, they feel that they need to be constantly watching the pH. They may set up monitoring and dosing systems to ensure the pH doesn’t go below 6 or 5.5. They are investing in extra equipment because they think they need to keep the pH precisely in this range. It may be a case that the plants will do well outside this range.”

 

Impact on crop timing

Baras said one factor that could affect the optimum pH and nutrient range is the light level.

“If a grower is providing supplemental light, then the optimum pH and nutrient range may be different,” he said. “With the trials we are conducting we aren’t that far off from what most hydroponic growers are targeting for growth rates. Thirty-five days is a target number for a lot of lettuce growers. We have done 35-day crops. We want to be able to grow an organic crop in the same amount of time as a crop grown with conventional fertilizers.”

 


For more: Hort Americas, (469) 532-2383; info@hortamericas.com; https://hortamericas.com.

 

David Kuack is a freelance writer in Fort Worth, Texas; dkuack@gmail.com.

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Hort Americas attends 2017 Philly Indoor-Ag Con

Philadelphia Academy of Fine Arts, Philadelphia, PA

Focusing on community, innovation, and technology like A.I, The Philly Indoor-Ag Con brought together some of the leading experts in these areas to discuss Indoor Agriculture and how it is beginning to change the landscape of cities around the world. Philadelphia may be one of the most primed cities to welcome indoor and vertical farms alike with support from individuals like Mayor Jim Kenney who spoke at the event.

The conference was divided into 4 sessions covering CEA opportunity to develop local communities, how technology is changing the indoor farm business model, the coming impact of LED lighting, and AI in indoor ag. Each session had 3 speakers with a Q&A panel at the end of every session. Some thought provoking questions even had the panelists looking at things from new angles such as Mark Benoit of Bright Farms’ question: “What about thinking in terms of mouths fed too, instead of just jobs created?” I personally believe that “mouths fed” or “healthy calories consumed” will be a very important analytic in the future as automated approaches become more accessible due to advances in technology.

A common theme during the conference was the need to unite and standardize within this new industry. I agree with this central idea as we need to treat ourselves like any agriculture industry which uses standardization to decrease waste and increase profits. Eric Stein, one of the panelists, is looking to build a Center of Excellence for indoor agriculture to combat this issue. (If you are interested in participating in a brief survey to assist with the project please visit kennettindoorag.info)

One of the key messages from the conferences was the idea that technology is affecting business at a rapid rate, especially within CEA. Whether we are talking about the leaps and bounds made by LED every year or the tools of the grower becoming more of a key to success, Hort Americas is able to offer technical support that the emerging field will need to understand this ever changing source of light. As Xandar Yango of San’an Bio stated “LED will drive this industry.”

Esteban Macias of The Coalition for Sustainable Organics posed the question “How do you disrupt before you get disrupted?” I believe that the more we come together in a transparent manner for conferences and events like Philly Ag-con the more we can ensure that we will be the disrupters, not the disrupted. At Hort Americas we aim to not only have a high standard of quality and service in everything we do, but aim to supply the disruptive growers with products, tools, technology and supporting technical information they need to be innovative and maintain profitability; these products range from lighting to hydroponic substrates to traditional and organic fertilizer. Working together to address and fill needs, we should insure that they continue to grow well into the future.

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Breeding crops for controlled environment production

Controlled environment agriculture growers have been trying to fit a square peg into a round hole by growing field crops in indoor environments. This is changing as research tries to match plant genetics with the production environment.

During this year’s International Congress on Controlled Environment Agriculture (ICCEA) in Panama City, Panama, University of Florida horticulture professor and keynote speaker Kevin Folta discussed the overlooked reality that food crop varieties have not been bred for indoor controlled environment production.

“One of the limitations of controlled environment agriculture (CEA) is that the conditions do not match the genetics,” Folta said. “Plants being grown in CEA environments were actually developed for field production. There are a lot of opportunities that go unrealized by growing plants in a controlled environment. It’s like asking Chihuahuas to pull a dog sled. Plants that were bred for one application are expected to perform under very different applications. The genetics don’t match.”

Research has begun to develop the next generation of plants with the potential to develop different products using the same set of genetics by changing the environment.

Creating the next generation of plants

Folta said research has begun to develop the next generation of plants with the potential to develop different products using the same set of genetics by changing the environment.

“By flipping a switch and varying the light spectrum we could change green leaves to purple or have the plants accumulate specific flavors or textures or nutraceutical compounds,” he said. “That is all very realistic. This is like being able to shine a different light spectrum on a Chihuahua and turning it into an Alaskan malamute or a dachshund. A plant’s body, its composition, its chemicals, its secondary metabolites could be altered by changing the light environment. We need plants that are ready to do that. We need to identify or create those genetics.

“We are exposing plants to different light spectra and evaluating how the plants behave and perform. Then we will work with plant breeders to develop the next varieties.”

Varying the light spectrum has the potential to change leaf colors and textures and to have plants accumulate specific flavors or nutraceutical compounds.
Photos courtesy of Kevin Folta, University of Florida

Need for more industry involvement

Folta said the companies that are developing and manufacturing the lights for CEA production should become more involved with the development of plants grown in these environments.

“The lighting companies should be working with the university researchers and plant breeders,” he said. “The lighting companies should be financing the development of proprietary varieties. Unfortunately that hasn’t been an area of interest for the lighting companies. They want to make and sell lights. They forget the seed. The seed is a much more complicated machine.

“The lighting companies should be able to say to the growers here are the grow lights we are offering and here are the seeds that grow best under them. That opens up recurring revenue for the lighting companies. It behooves the lighting companies to focus on identifying plants that perform best with their products. It’s like saying that a Ford engine does best with a Motorcraft oil filter. It’s manufacturer’s optimized matching parts.”

Folta said plants are the most complicated part of matching the genetics with the environment and the part that people worry least about.

“It doesn’t matter whether the breeding company or the lighting company takes the initiative to develop the genetics,” he said. “This is going to happen whether it’s private plant breeders, universities or technology companies. This is another niche to create new genetics. You’ll see people filling this void.”

Researchers are learning that green, far red and UV light have important roles to play in controlled environment agriculture plant production.

Limiting, changing the production environment

Even technology companies like Panasonic, Toshiba and Fujitsu are finding opportunities in controlled environment agriculture.

“These types of companies will develop the genetics or will find the genetics that work well in CEA environments,” Folta said. “For now the field genetics will continue to be put in artificial conditions and the indoor environment will be reshaped to accommodate the plants. What should be done is finding or developing plants for these energy-efficient, artificial conditions that are sufficient to support growth. Research needs to be done to determine how to maximize output or yields with fewer photons of light or colors of light. Research is going to focus on economic viability. I expect the pharmaceutical companies will get involved in this research.

“My interests are much more about food and how we create the next generation of profitable growers and higher nutrient crops that are more readily available for consumers. That’s what gets me fired up.”

While matching the genetics to fit the environment is important, Folta said researchers also need to be looking at limiting the environment.

“At the same time that we are looking at the breeding and genetics, we are also looking at how we can deliver shorter pulses of light that still maintain the same output,” he said. “We have cut energy application by 50-80 percent and grown comparable products. The viability of these systems has come from people who have focused on the diminishing return of light efficiency. What they need to work on is the plant efficiency. That is something that is extremely viable.”

Folta said all of the research he has been focused on is with small format, high value crops, including lettuces, sprouts and microgreens.

“Our university does not have the facilities to conduct the necessary experiments,” he said. “But we are partnering with others to do that. We will have good access to larger spaces in the upcoming months. It’s less likely that this type of production would be done with crops that take more space like melons. We are looking at plants where the vegetative portions of the plants are eaten. If you consider a head of lettuce, every photon that is invested results in the plant structure. With a crop like tomatoes, 80-90 percent of the biomass is being thrown away or composted.

Kevin Folta at the University of Florida is interested in how to create the next generation of profitable growers and higher nutrient crops that are more readily available to consumers.

“Growing the plants in shorter production times, shorter supply chains, better postharvest quality because of shorter supply chains, possibly lower costs, a lower carbon footprint and access to local markets, these are the issues I want to address. I see this being done with lettuces, microgreens and herbs such as cilantro and basil. Not so much with corn or melons where a huge amount of energy is invested in a relative small return in terms of calories. These types of crops do better using the sun.”

Folta said 15 years ago people thought the idea of light recipes and changing the spectrum was a crazy and senseless idea.

“Researchers and light manufacturers thought mixtures of red and blue light were all that was needed to grow plants in controlled environments, so there wasn’t any concern about doing anything different,” he said. “Now people understand that green, far red and UV light have important roles and that light quality should change throughout the day. With that in mind, it gives us some flexibility when it comes to changing the production environment, which is a really good thing.”

 


For more: Kevin Folta, University of Florida, Horticultural Sciences Department, Gainesville, FL 32611; kfolta@ufl.edu; http://www.hos.ufl.edu/faculty/kmfolta.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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2017 AVF Summit in Washington, D.C

By Kyle Barnett

The AVF Summit in Washington D.C was a great event to get a very eclectic group of people together that all want the same thing: to feed people and grow food sustainably as we move into a future that is rapidly growing and urbanizing.

University of the District of Columbia

Recent grads, farmers, politicians, and tech driven individuals all had a chance to discuss the future of vertical farming and urban farming including topics such as policy, certification, zoning, and the politics behind the future landscape of agriculture. The summit went into a lot of the bureaucracy surrounding urban and vertical farming and what it truly means to have a well thought out plan before you start growing.

Association for vertical farming

The day-long summit was separated into multiple sessions with presenters from across the urban farming and tech industries, including but not limited to Sonny​ ​Ramaswamy​ ​(The National Institute of Food and Agriculture), Dr​ ​Bob​ ​Whitaker​ ​(Produce Marketing Association), and Roberta​ ​Anderson​ ​(Global G.A.P.). Most sessions were accompanied by a Q&A panel of industry professionals, each having a unique perspective on the specific topic of that presentation. Starting with a focus on policy, followed by Standardization & Certification, and finishing the day with the politics behind The Farm Bill, the summit painted a broad picture of what the future farming landscape may look like.

Much like the summit, the future of farming will be a combination of many different subjects and professions, with different skills, opinions and knowledge uniquely coming together to create the way we grow and eat. Hort Americas is proud to support this diverse industry. Working with every type of farm from conventional to vertical, our goal is to assist the industry with not only superior equipment and supplies, but with technical expertise and hands on experience.

For more information on the Association for Vertical Farming, click here.

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AmericanHort technology tour to visit Hort Americas hydroponic research greenhouse

Tour of Hort Americas research and demonstration greenhouse in Dallas will show growers different hydroponic production systems for various vegetable crops.

Growers of hydroponic vegetables or those considering starting growing vegetables hydroponically should plan on attending the AmericanHort Production Technology Conference. Scheduled for Oct. 9-11 in Dallas, the conference begins with a Technology in Action Tour on Oct. 9 which will visit three local production operations: Hort Americas research and demonstration greenhouse, Seville Farms and Southwest Nursery.

 

All things hydroponic

Hort Americas, a horticulture and agriculture wholesale supply company, has retrofitted a 12,000-square-foot floriculture greenhouse for the hydroponic production of vegetable crops. Tyler Baras, who is the special projects manager at Hort Americas, is overseeing the trialing of five different production systems along with the testing of potential products for the company’s online catalog. The production systems include: nutrient film technique (NFT), deep water culture floating raft, a vertical hydroponic tower system, a flood-and-drain vertical rack system and a new capillary mat manufactured in Europe. The greenhouse is being used to grow a wide variety of lettuces, leafy greens, herbs and microgreens.

During the AmericanHort Technology in Action Tour on Oct. 9, Tyler Baras, special projects manager at Hort Americas, will be talking about the five different hydroponic production systems he is trialing.
Photos courtesy of Tyler Baras

The NFT system uses a new channel design. Baras said the narrower channels allow for the aging of crops without having to physically move plants from nursery channels to finishing channels.

Hort America’s main floating raft deep water system is an in-house custom design that measures 32-feet by 28-feet.

“We have tried using a Venturi system to incorporate oxygen, but for the last two months we have been doing trials with compressed liquid oxygen,” Baras said. “We have been doing trials to see how plants respond to increased levels of dissolved oxygen. This deep water system hasn’t been flushed in over a year.

“We have been managing the nutrient solution with water tests and individual salts. Instead of using a standard N-P-K fertilizer like we have been using in the other production systems, we have really focused on water tests and making nutrient adjustments based on those tests. We have been trying to keep the nutrients within a target range and trying to run the system for as long as possible without having to flush any of the nutrient system. We are testing for all of the essential nutrients. We are also looking at sodium chloride levels and seeing how those accumulate. Also, we are tracking what essential nutrients accumulate over time and how we can adjust the fertilizer being added to accommodate the natural accumulation in the system.”

In addition to trialing crops in different hydroponic production systems, Tyler Baras is also studying a variety of crops grown with conventional and organic substrates and fertilizers.

 

Baras is also studying how the water source can contribute to the nutrient level.

“We are considering how source water may be a limitation to applying this no-flush technique,” he said. “Our source water is municipal water, but it has a high sulfur content of about 44 parts per million. So we are looking at cutting out all sulfur inputs. We are learning the challenges of trying to manage a no flush system.”

In addition to the main deep water system, Baras said tour attendees will also see several smaller deep water culture systems.

“In these smaller deep water culture systems we will be showing the use of three different organic fertilizers where we are comparing the growth between them,” he said. “We will also be showing a smaller scale deep water culture system receiving aeration compared to one with no aeration.”

 

Vertical production systems

Another hydroponic system that Baras is working with is a vertical tower commonly used by smaller growers.

“We have a lot of customers who use this system so we decided to install one in the greenhouse so we could look at some of the issues that they are dealing with,” he said. “We also were looking to answer some of the questions that our customers had about using the system. An example is can this system be used to grow organically? We’ve done both organic and conventional trials with this system.

“We’ve also been looking at what crops perform best in this vertical system. We’ve done a lot of variety trials as well as with the other systems we’ve installed.”

Hort Americas is also trialing a vertical Growrack from Growtainer.

“This is a flood-and-drain vertical rack system,” Baras said. “The rack has three levels, but it could be expanded. The rack has a 2-foot by 5-foot footprint. We have equipped it with GE LED lights. This would be the type of system used in a vertical farm setup.”

Although the Growrack hydroponic system can be used to grow full size crops, Tyler Baras is using it primarily for seedling propagation.

Baras said the Growrack system, which is set up in the greenhouse, has done well in warm conditions because its water reservoir is below the rack.

“The reservoir is usually stored underneath the racks so it is in shade,” he said. “The water isn’t always in the trays so it doesn’t collect the heat from the trays. It works well in warm climates.”

Although Baras has grown full size crops in the Growrack, it is being used now primarily for seedling propagation.

“The focus of the system is how it has enabled us to cut back on the amount of space that is needed for propagation,” he said. “We can easily grow enough seedlings in this system for a 10,000-square foot greenhouse.

“The system is also being used by a Central Market store in Dallas to finish crops for its Growtainer farm. We helped consult on the management of the system and showed store officials how it could grow crops from start to finish in the same Growracks. The store is growing fully mature butterhead lettuce and basil in the system. This system can definitely work in indoor vertical farms.”

Baras said he has grown both organically and conventionally with the Growrack system.

“We have done organic seedling propagation in it,” he said. “We have used a variety of conventional and organics substrates and fertilizers with it.”

 

LED studies

In addition to trialing LED lights vs. natural light for greenhouse seedling propagation and crop staging, Baras said he is also looking at using LEDs supplemental light throughout the production of butterhead lettuce in the floating raft system.

“We are looking at how LED light affects leaf texture and plant morphology of butterhead lettuce,” he said. We are trying supplemental lighting during the summer. We are pulling shade so the light isn’t very intense. It appears that intense light can lead to tip burn that damages the plants leading to a poor quality crop. So we pull shade cloth and then run a prototype high-output LED grow light provided by GE for almost 20 hours. We deliver a low intensity of light over a longer period so we can provide the plants the light they need without stressing them. We are trying to improve the quality by adding LED light in order to produce more compact growth that is associated with LEDs.

“Under greenhouse shade cloth the lettuce leaves look fragile. We are trying to grow the lettuce to hit a certain weight. If the plants are grown under shade they look fairly large and floppy and the head doesn’t have the right density at its core. By using the LEDs we can produce the more traditional morphology where the plants have a dense core. The leaves aren’t floppy and the plants look more like traditional butterhead should look.”

 

Matching plants and production systems

Baras said he is trialing a wide range of crops in all of the production systems he is using.

“Primarily we are focused on lettuce and basil, but we are trialing a lot of varieties,” he said. “We definitely see some systems are capable of growing some varieties that other systems are not. We want to be able to recommend what varieties grow best in what systems. We are preparing a book based on our research that will include an entire section on strategies for how to use these production systems. We will provide example situations in the book discussing location, climate, market, what crops are being requested by that market and how to use that information to determine what production system is most appropriate.

“We are looking at primarily butterhead, romaine and oakleaf lettuce and 20 different basil varieties. We are also doing trials with arugula, spinach, cilantro, kale, chard, Asian greens and microgreens. We are doing an extensive study of herb varieties. There are also some unusual crops like stevia, wasabi arugula, celeriac and sorrel. We are determining all of these plants growth habits in the different production systems. This information will be in the book along with the details and nuances of growing each crop.”

A vertical hydroponic tower commonly used by smaller growers has been installed to answer some of the questions that Hort Americas customers have about using the system.

Based on the trial results, Baras said the book will provide details on each plant variety and its performance in each system.

“The book will provide information on the growth a grower should expect in different environments based on the amount of light and temperature,” he said. “The book will offer projected production numbers a grower should be able to reach. These will be realistic targets for each of the production systems we have studied.”

 


For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

 

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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GLASE consortium aims to improve greenhouse energy efficiency

Even though the Greenhouse Lighting and Systems Engineering (GLASE) consortium is New York-based, the research it is doing has the potential to impact controlled environment agriculture worldwide.

The Greenhouse Lighting and Systems Engineering (GLASE) consortium is a partnership between Cornell University in Ithaca, N.Y., and Rensselaer Polytechnic Institute (RPI) in Albany, N.Y. The consortium will be conducting research to improve controlled environment agriculture (CEA) operations including reducing energy consumption.

 

 

The goal of the consortium is to create a more sustainable and profitable greenhouse industry. Although the focus of the research will be on greenhouse production, the findings should also have application to indoor CEA production including vertical farms and warehouses. Greenhouses, which can be electricity-intensive depending on the level of automation, cover 720 acres in New York State. The consortium is looking to reduce greenhouse electricity use and concomitant carbon emission by 70 percent and to increase crop yields by 2030.

Erico Mattos, who was appointed executive director of GLASE in June, said he has been hired as a subcontractor by Cornell University and will be working to recruit industry members to join the consortium.

“Currently I have a 50 percent time appointment with GLASE,” Mattos said. “My time with GLASE will increase as we bring in industry members. I am living in Georgia, but will be moving to upstate New York over the next year and will be located between RPI in Albany and Cornell University in Ithaca.”

Mattos said GLASE is a seven-year project which has received $5 million from the New York State Energy Research and Development Authority (NYSERDA). The money will be used to sponsor research between Cornell and RPI.

“The team leaders who will be doing the research are Neil Mattson at Cornell University and Tessa Pocock at RPI,” said Mattos. “They have a set of more than 300 milestones that their teams have to reach. They have already achieved some of these milestones.”

The research activities include improving lighting fixtures and systems that synergistically control lighting, ventilation, humidity and carbon dioxide, improving CEA operations and reducing energy consumption to create a more sustainable and profitable greenhouse industry.

“The teams at Cornell and RPI are well equipped with the resources they need to achieve the milestones of the core research proposal that has been sponsored by NYSERDA,” he said. “Even though the teams led by Neil and Tessa are completely self-sustainable, they may require some outside partnerships to achieve some of the goals.”

The GLASE consortium is headed by researchers Tessa Pocock at Rensselaer Polytechnic Institute and Neil Mattson at Cornell University and GLASE executive director Erico Mattos.
Photo courtesy of GLASE

Mattos said in his role as executive director he will act as an intermediary between Cornell, RPI and NYSERDA making sure that the research is proceeding and that milestones are being completed on time.

“The most important part of my position is to create a consortium with industry members,” Mattos said. “The goal over the next seven years will be for the project to receive less money from NYSERDA and more money from industry members. We want to establish a consortium that is self-sustaining. By bringing in industry members we will have money to do our own-sponsored research, technology transfer, outreach, and market research, all these types of things and GLASE will be self-financing.

“My role as executive director is to ensure that the team moves in this direction. By bringing in industry members, offering them the project and making sure that we provide them with access to the technology that is developed by Cornell and RPI.”

 

Complementary research

Mattos said the research that will be done at Cornell and RPI is complementary and will not overlap.

“RPI will be doing more engineering-related research, such as looking at light fixtures and components including the drivers and controllers,” he said. “They are also looking at photobiology—how plants respond to different spectra as they grow and produce different nutritional compounds and changes in plant metabolism and morphology. The RPI research work is more engineering-related.

“The research at Cornell is going to be more applied in the greenhouse, such as interactions of carbon dioxide enrichment and lighting control studies. Cornell will implement some of the systems that have already been developed at Cornell. Cornell will also be looking at different systems and different crops. Initially the studies will be done with tomatoes, lettuce and strawberries and then will be extended as necessary.”

 

The research conducted at Cornell University will be more applied in the greenhouse, including carbon dioxide enrichment and lighting control studies.
Photo by Chris Kitchen, Cornel Univ. Marketing

Mattos said the research will be expanded to commercial size greenhouses in New York, which will be 6,000 square feet for a small scale greenhouse and 20,000 square feet for a large scale greenhouse.

“RPI will develop new systems and Cornell will implement the greenhouse tests and then move forward to a final demonstration,” he said.

Mattos said the researchers will also be working in partnership with A.J. Both at Rutgers University, who will be doing some of the energy efficacy and radiometric studies of the light fixtures.

“One of the milestones Cornell research associate Kale Harbick will be working on is modeling,” Mattos said. “This will involve trying to calculate in advance how much energy in a greenhouse is consumed and what happens if some of the variables are changed. The research will look at how these changes affect the general energy consumption of the greenhouse.”

 

Seeking industry support

Mattos said when GLASE was developed over 30 industry companies provided letters of support indicating they wanted to become part of the consortium as industry members. Since the consortium was started, many other companies have expressed their interest in becoming part of the consortium.

“Even though these companies signed letters of support that doesn’t mean they will all become consortium members,” he said. “Cornell and RPI are both already working in partnership with some companies to develop the core research. There is nothing official as industry members yet. We are looking to bring in other industry members and really make them a part of this consortium. We want to reach a broad range of industry members so this support could be both financial or it could be providing equipment to conduct the research. But the primary goal is to bring in financial support.”

Mattos said there will be a series of benefits that come with industry membership.

“They would pay for a membership and then they would get a series of benefits. We are now working with a marketing media company to promote the consortium and the opportunity for membership.

“We want to bring in large manufacturing companies, but we also want to address the other end of the spectrum and work with small growers. The growers will benefit the most from this research.”

 

Academic collaborators, information hub

Mattos said it is the intension of the consortium to expand with researchers from outside New York.

“We intend to establish future academic collaborations to develop new research projects partially funded by GLASE through industry membership funds and new research grants,” he said.

Another goal of GLASE is to create a hub for greenhouse lighting and systems engineering which includes the centralization of information.

“We will create a central database to indicate the academic research currently on-going in the U.S. (what, where and who) to facilitate the interaction between the industry and academia,” he said.

 

Impact on greenhouse, plant systems

The crops that are to be studied initially by Cornell and RPI researchers are tomatoes, lettuce and strawberries.

“These are commercially relevant crops,” Mattos said “I went to Ithaca and met some of the members of Neil’s team, including graduate students Jonathan Allred and Erica Hernandez and research technician Matthew Moghaddam, who have been working with tomatoes and strawberries. Lettuce is also one of the most commonly produced greenhouse crops.

“Part of the milestones that Tessa will be working on will be done in environmentally controlled growth chambers and growth rooms. Tessa does not have a greenhouse. Most of the research that she will be doing is related to photobiology. Everything that she will be doing has application to warehouse production even though she is not doing the research in a warehouse. This research will look at nutritional compounds and pigment production. The research in the growth chambers will be compared with greenhouse studies.”

The research conducted at RPI will be done in growth chambers and growth rooms, which should have application to commercial warehouse production.
Photo courtesy of GLASE

Although the RPI research is not targeted for commercial indoor farms, Mattos said the results could be used to support that type of production.

“The proposal is to reduce greenhouse crop production energy consumption by 70 percent in seven years,” he said. “The economic factor and the majority of the research will be looking at greenhouse systems and how to integrate them. Economically we are focused on greenhouses. But we will be doing studies in growth chambers that may have application to support indoor farm production.

“Tessa will be looking especially at biological efficacy. Everybody talks about the efficacy of the light fixtures themselves. A lot of people are looking at that. Getting less attention is the biological efficacy, which is if there is a different spectrum, the same amount of photons or micromoles, can have a different impact on plants. Not only the morphology, but also the pigments, the chemical pathways. This is the biological efficacy.”

 


For more: Erico Mattos, Greenhouse Lighting and Systems Engineering (GLASE) consortium; (302) 290-1560; erico.bioenergy@hotmail.com; https://glase.cals.cornell.edu.

 

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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Victor Loaiza Mejia joins the Hort Americas team

Hort Americas is proud to announce that Victor Loaiza Mejia has joined our team as the Technical Sales Manager for California, Oregon and Washington.  Victor studied agronomy in Mexico and did a year of study at Cal Poly San Luis Obispo in California. After graduating he worked for Koppert Mexico and for British American Tobacco. In 2005, Victor received his masters of science degree from Wageningen University in the Netherlands.

His new found specialties in greenhouse horticulture and controlled environment agriculture then took him to the Netherlands where he worked three years for Royal Pride Holland as a grower before he came to the United States and joined Eurofresh Farms in Wilcox, Ariz. At Eurofresh he worked as a production manager and later took over the final implementation of Priva FS. Eurofresh Farms was bought by Nature Sweet in 2012.

In 2013, Victor became one of the first urban growers when he became the lead grower at Gotham Greens in Brooklyn, N.Y. At Gotham Greens Victor wore many hats and helped manage all operational aspects of the business. Victor left Gotham Greens after three years and moved back to California.

Victor has extensive experience in growing leafy greens and tomatoes under very varied production circumstances. He has worked with all types of software and has hands- on experience in organizing labor.

Please join us in welcoming Victor to Hort Americas.

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The impact of transplanting times, light exposure on hydroponic crop production

How quickly hydroponically-grown lettuce and leafy greens seedlings are transplanted and their exposure to LED light during propagation can impact crop production times.

Most growers using traditional hydroponic substrates transplant lettuce and leafy greens seedlings as soon as the roots reach the bottom of the plugs. This usually takes from seven to 10 days.

“We are trying to see if we can go far longer in Stage 1, which is this seedling stage,” said Tyler Baras, special projects manager at Hort Americas in Bedford, Texas. “Stage 1 occurs in a propagation area.

“Some growers incorporate an intermediate phase (Stage 2) which is a growing out stage. Stage 2 might consist of nutrient film technique (NFT) channels closely spaced next to each other or a deep water raft system with high density spacing. Generally a 2-foot-by-4-foot raft holds 72 plants or more. Both Stage 2 and 3 occur in the final growing out system. During Stage 3 those same NFT channels are spaced further apart or in a deep water system the plants in a 72-count raft are transplanted to a lower density 28- or 18-count raft.”

Some hydroponic growers incorporate an intermediate Stage 2 during which nutrient film technique channels are spaced close together.
Photos courtesy of Tyler Baras

Baras said holding the seedlings in Stage 1 for a longer period would reduce the amount of time that is required in the final Stage 3.

“This would actually be a two-stage system with an increase in time the seedlings are in the propagation stage or Stage 1,” he said. “Our reason for doing these studies is to see if we can eliminate the labor required to transplant the plants from Stage 2 to Stage 3, but still achieve yields similar to three-stage systems. Three-stage systems generally achieve more crop turns per year than two-stage systems. For many small growers trying to find enough labor and high labor costs can be major issues. If we can reduce the amount of labor required by extending Stage 1 this could help growers.”

Baras said the reason most growers don’t try to grow the seedlings longer during Stage 1 is the chance for root damage that can occur when the plugs are transplanted into the final production system.

 

Most growers are concerned root damage may occur when plugs are transplanted into the final production system if they hold seedlings too long in Stage 1.

“If seedlings are held too long, especially in a sheet substrate where there isn’t any divider between the plants, the roots can easily grow into the neighboring plugs,” he said. “When a grower goes to transplant the plugs and tries to pull them apart damage can be done to the roots. When the plugs are transplanted into the final system this root damage can lead to stunting and leaf dieback. The damaged leaves are more susceptible to disease pathogens and can attract fungus gnats. The plants will also require additional cleaning at harvesting to remove damaged leaves.”

Baras has observed the problems caused by holding the plugs longer in Stage 1 occur more often with transplanting into NFT systems than with deep water raft culture.

 

Promising results

Baras said that he has conducted several trials with different substrates holding the seedlings in Stage 1 up to six weeks.

“We have gone the longest with self-contained plugs,” he said. “This is usually with organic production where there is slower growth. We have pushed the seedlings for a longer period of time. So far the best results with conventional hydroponic production are at about three weeks. With organic production it’s around four weeks because the plugs are self-contained and the roots don’t grow into neighboring plugs.

“We are pushing some of the seedlings to nearly a month and not seeing significant leaf dieback or stunting from root damage. We are shaving off several weeks within the final production system. It’s still possible to damage the seedlings if they are held in Stage 1. We are seeing the upper limit is higher for deep water culture than it is for NFT.”

 

Impact of LED lighting

Baras said another factor that can impact seedling development is exposure to supplemental light.

“We have been trialing different photoperiods and light intensities,” he said. “We have found that the light treatments that we give the seedlings can actually affect whether the plants produce more roots or more leaves. We are looking at the differences between exposing the seedlings to sunlight and LED light from GE Arize Lynk fixtures and different photoperiods.

“Depending on the lighting treatment we can create a smaller plant on top but increase root mass. This allows us to grow the seedlings longer without the plant canopies growing into each other. When the seedlings are removed for transplanting there is no damage to the leaves. There are more leaves left intact by growing more compact plants. We are still able to get a lot of root development.”

One of the most exciting findings that Baras is seeing is the increase in final weight of lettuce given LED supplemental light.

“When we started our research we were using traditional production methods,” he said. “We would sow the butterhead lettuce seed and place the trays under sunlight and then transplant the seedlings between seven to 14 days. With this traditional growing method we would produce a 6-ounce head. With the adjustments that we are making to staging and using LED lighting we are producing 8-ounce heads in the same amount of time. We are very excited about that. We think it is one of the most significant things coming out of our research greenhouse right now.

“The plants grown with LED light are finishing with 2 ounces more of plant weight. This seems to be related more to light quality and the influence that it has on the seedlings’ morphology than on total light received. It is not like the plants are receiving a lot more light when they are exposed to LEDs instead of sunlight. The morphology of the plants is completely different because of the light quality spectrum they are receiving. We now want to look further at light quality treatments during the seedling stage. This includes different ratios of blue/red LEDs, the inclusion of different colors and checking for variety specific results. There are still a lot of trials to do.”

 

Butterhead lettuce seedlings lit with LED lights during propagation are producing larger heads in the same amount of time as seedlings exposed to sunlight during propagation.

One of the trials that Baras wants to study further is varying the length of time the lights are on.

“We are also looking at how long the lights are on,” he said. “Whether there is a big difference depending on the length of the photoperiod. We have not found an optimum length of time. We have found that more light is not always better.

“We are looking at exposing the seedlings to 20 hours or 24 hours of light. Right now 20 hours of light is outperforming 24 hours of light. But 24 hours of light is outperforming natural sunlight. This is across all crops, including a couple varieties of lettuce and Italian basil.”


 

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

 

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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Nutrient guidelines for hydroponic tomato production

By Victor Loaiza, on behalf of Hort Americas

It is important to conduct water and nutrient solution analyses on a regular basis to ensure hydroponic tomatoes are receiving the proper level of nutrients.

Making sure that hydroponically-grown tomatoes receive the proper nutrient levels requires testing water and nutrient solutions. Growers also need to confirm that irrigation equipment is delivering the correct amount of fertilizer. Nutrient levels should be monitored and adjusted according to the crop developmental stage, the season, light levels and tomato type.

“In applying fertilizer to a plant grown either in soil or in a soilless medium, the goal is to match the nutrient uptake of the crop as closely as possible to the amount provided as fertilizer” (Mary Peet, USDA, Division of Plant Systems-Production, 2005). There are many reasons to do so, but a very important reason is to prevent fertilizer runoff which is actually money runoff.” For growers with open irrigation system this will hurt the most. In a closed irrigation system, excess fertilizer is recovered and recycled after water treatment.

Water sample analysis

It’s very important to regularly conduct irrigation water and nutrient solution (water + fertilizers) analyses. Irrigation water quality from a well, dam or municipal system should be determined before implementing any type of fertilization plan. Important levels growers should know include: water electrical conductivity (EC), water pH, sodium (Na), chloride (Cl) if using a municipal water source, calcium (Ca), magnesium (Mg) and sulfates (SO4). The preference is for low levels of all these elements. Water EC less than 0.5 millisiemens/centimeter (mS/cm) is a good level. If the water pH is high, a pretreatment can be done with sulfuric acid, phosphoric acid or citric acid. Optimum and safe pH levels are between 5 and 6.

Nutrient solution sampling should be conducted on a weekly or biweekly basis. Nutrient solution sampling should be taken from two sources:

1. Feed is the nutrient solution the irrigation system is pumping to the plants sampled at the dripper.

2. Drain is the leachate coming from the substrate. This is critical to a fertilization strategy.

Useful information

The information obtained from the nutrient solution analysis helps to:

1. Verify the irrigation equipment is dosing the correct amount of fertilizer.

2. Verify the EC and pH of the nutrient solution are satisfactory levels.

3. Determine the amount of fertilizer by element being absorbed by the plants.

4. Determine the amount of fertilizer that needs to be added/subtracted from the nutrient solution.

It can be determined if the amount of irrigation is appropriate by looking at the drain EC. If the EC is too high, there may not be enough water being applied to the plants. If the EC is too low (lower than the feed EC) plants may be receiving too much water.

5. Verify if the amount of irrigation is appropriate by looking at the drain EC. If the EC is too high, there may not be enough water being applied to the plants. If the EC is too low (lower than the feed EC), plants may be receiving too much water.

There are many laboratories that perform this type of water and nutrient solution analysis. It is important to choose a lab where the staff has experience in hydroponics.

Two recommended laboratories are Groen Agro Control in the Netherlands and Perry Laboratory in Watsonville, Calif.

Recommended nutrient levels

A Netafim fertilizer controller unit

In the photo of the Netafim crop management technology fertilizer dosing unit, the blue line on the left is the irrigation water (well water or municipal water with no fertilizer). This water is pumped to the mixing chamber where fertilizers are injected and the water becomes the nutrient solution (pink line on the right). The nutrient solution flows through EC and pH sensors to make sure that the target EC and pH are maintained.

Table 1 shows the nutrient levels by element or molecule recommended for tomato nutrient solutions measured at the drain. Elemental levels at the lower or higher margins are not necessarily bad. Maintaining the proper nutrient level is crop dependent.

Table 1. Nutrient solution elements in drain water

Table 1 reflects the desired values obtained by a drain sample analysis. By constantly analyzing the nutrient solution, the target levels can be matched that best suits the crop.

Preparing nutrient solutions

The most common chemicals for mixing nutrient solutions are mentioned in the Hort Americas article on hydroponic greenhouse pepper production.

They include:

  • Ca(NO3)2 (Calcium nitrate)
  • KNO3 (Potassium nitrate)
  • KH2PO4 (Mono-potassium phosphate)
  • MgSO4*7 H2O (Magnesium sulfate)
  • H3BO3 (Boric acid)
  • MnCl2*4 H2O (Manganous chloride)
  • CuCl2*2 H2O (Cupric chloride)
  • K2SO4 (Potassium sulfate)
  • MoO3 (Molybdenum trioxide)
  • ZnSO4*7 H2O (Zinc sulfate)
  • Fe Sequestrene 330 (iron chelate)

General recommendations

  • Some tomato varieties are more susceptible to blossom end rot (BER) http://ucanr.edu/sites/placernevadasmallfarms/files/86509.pdf) than others. Check irrigation strategy and nitrate levels since high nitrates could be the cause of BER.
  • Keep daily irrigation measurements in a logbook (EC, pH and drain percentage). This is a daily task that should be performed early in the morning before the irrigation cycles start. See handheld EC/pH meters https://hortamericas.com/product-category/growing-supplies/meters/
  • Compare the manual EC/pH readings with the irrigation unit readings, they should match.
  • Keep K:Ca ratio close.
  • Calibrate pH and EC meters once a week.
  • Calibrate pH sensors on the irrigation unit at least once a month.
  • Keep the irrigation system clean and flush it periodically.
  • Clean fertilizer tanks every month to avoid fertilizer sedimentation.
  • Keep the pH of the micronutrient stock tank low (pH 4).

 


 

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

 

Here are some of the fertilizers Hort Americas offers:

 

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Hort Americas offers OSRAM horticultural LED lights

Hort Americas is now offering OSRAM’s ZELION HL300 series of horticultural LED fixtures including controls and accessories. One of main advantages of the fixtures is they are controllable allowing users to adjust both the light intensity (light quantity) and the spectrum (light quality).

The ZELION HL300 Grow Light is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture. It is designed to meet the plant spectra needs for optimum photosynthesis and energy efficiency resulting in faster growth and increased yields.

The ZELION HL300 Sunlight is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture recommended for growth chamber applications where natural light is important or for supplemental lighting where color recognition is important, i.e., in a garden centers. To accommodate an increasing demand from a variety of users, including plant researchers, growers and garden centers, a spectrum was designed to closely match natural sunlight.

The ZELION HL300 Grow White is a 100- to 600-watt dimmable and spectra-tunable LED horticulture light fixture designed for horticulture applications. It is designed to meet the special lighting requirements of growers.

The Grow White has a combination of the ZELION Grow Light and Sunlight fixtures’ spectrum. This spectrum is used in growth chambers where a higher photosynthetic activity is required or by growers requiring supplemental light where color recognition and rapid, healthy growth are key factors.

All of the fixtures in the ZELION HL300 series emit light in the photosynthetically active region (400–700 nanometers) of the visible light spectrum. Their optimized design makes the lights easy to install and they provide the smallest shadow footprint compared to similar class LED fixtures. The lights are designed to withstand crop production environments.

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Be aware of the challenges of using loose substrates in hydroponic production systems

If you’re going to use a loose substrate in a hydroponic production system, you may have to change how you handle starter plants and the treatment of recycled water.

Many growers of ornamental plants including annuals and perennials traditionally use a peat-based substrate such as 70 percent peat, 30 percent perlite. The growers, who produce these crops in containers, will often use the same substrates if they expand their crop offerings to include hydroponically-grown edible crops, including lettuces and leafy greens.

“There are some growers who use these peat-based substrates in hydroponic production systems, but it is more difficult to manage because hydroponic systems need to run clean,” said Tyler Baras, special projects manager at Hort Americas in Bedford, Texas. “Debris from these loose substrates can lead to clogging of irrigation lines in hydroponic systems like nutrient film technique (NFT). In the case of a deep water culture floating raft system the goal is to flush the system as infrequently as possible because there is so much water involved. Growers want to keep both of these hydroponic production systems fairly clean.

“The loose substrates used by traditional bedding plant growers can break apart so that there is some peat and perlite floating in the system or sinking to the bottom of the pond or water reservoir.

Debris from loose substrates like peat and perlite can lead to clogging of irrigation lines in hydroponic systems.
Photos courtesy of Tyler Baras

Baras who recently completed trials with loose substrates in a 12,000-square-foot research and demonstration greenhouse in Dallas said the more commonly used substrates for hydroponic systems are inert materials. These include preformed plugs, such as stone wool plugs or cubes, polyurethane foam blocks, stabilized medium like synthetic polymer peat plugs and wrapped plugs which can have an outside coating like Riococo Closed Bottom Organic Plugs.

Focused on root growth

In the greenhouse trials that Baras is doing with lettuces and basil in NFT and deep water raft systems, he is studying the differences between peat and coir.
“Coir has more water retention from what we have seen,” he said. “It really depends on the production system, the growers’ staging strategy and how the seedlings are watered. There are a lot of factors that are similar and they both have the possibility of being used for hydroponic production.

“Coir is often used as a substitute for peat. Often when coir is used, growers have to change their irrigation strategies. Fine coir holds more water than peat. Once the seed has germinated and is at the seedling stage the goal is to establish a strong root system regardless of the substrate used. The plug should be dominated by roots. As long as the plug has a large enough root mass once it is transplanted into a hydroponic system, there is a good chance for success.”

Seedling plugs transplanted into a hydroponic system should be dominated by roots regardless of the substrate used.

Growers should consider young plant development strategies specific to the substrates they are using.

“An example would be plugs with some type of wrapping around the outside,” he said. “The bottom is open, but the plants should be grown until there are enough roots to cover the bottom of the plug so it doesn’t fall apart once it is placed in the hydroponic system.”

Limited choice of organic substrates

Baras said growers doing organic hydroponic production have a more limited selection of substrates.

“Growers who want to grow organically can’t use stone wool, foam blocks or any polymer peat plug,” he said. “Organic production is generally limited to loose substrates. This would include loose peat- or coco-based substrates and coco plugs. There aren’t a lot of options.

“If a loose substrate is used and some of it is falling apart and into the production system it can quickly clog the irrigation system. It’s important to have a solid root structure before transplanting the plugs into an organic hydroponic system.”

Although organic production is generally limited to loose substrates, the Riococo Closed Bottom Organic Plug offers an alternative stabilized medium.

Whether growing organically or not, when using loose substrates in hydroponic systems, Baras said growers need to have a good filtration system.

“Anything coming off the tail end of the NFT channels is going to have to be run though some kind of filtering stage to collect any debris before the water goes back into the reservoir,” he said. “The irrigation lines are usually ¼-inch or smaller and those can clog quickly when loose substrates like peat or coco are used.”

 


For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

For more information on choosing a substrate for hydroponic production systems, https://hortamericas.com/grower-resources/growing-media-and-substrates/

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

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Nutrient recipe for hydroponic greenhouse bell peppers

Bell peppers grown in greenhouse hydroponic systems follow similar environmental requirements as tomatoes and eggplants. It is a common production practice to leave all the leaves on the pepper plants. This creates very tall walls of foliage that slightly affect the plants’ nutritional requirements.

Pepper growth follows generally two different phases during greenhouse production. After the seedlings are transplanted, the first six weeks of production is geared toward developing a strong vegetative base. After fruit set, the nutrient recipe is changed slightly to keep the plants in balance. For peppers only potassium is significantly increased after fruit set occurs.

Table 1. Nutrient solution for hydroponic pepper cultivation.

0-6 weeks Mature crop
Reference EC 2.2 mS/cm 2.5mS/cm
Nitrate (NO3) 200 ppm 180 ppm
Ammonium (NH4) 7 ppm 15 ppm
Potassium (K) 240 ppm 270-300 ppm (200 ppm*)
Phosphate (PO4) 50 ppm 50 ppm
Calcium (Ca) 220 ppm 200 ppm (300 ppm*)
Magnesium (Mg) 50 ppm 45 ppm
Iron (Fe) 1.5 ppm 1 ppm
Manganese (Mn) 0.55 ppm 0.55 ppm
Zinc (Zn) 0.33 ppm 0.33 ppm
Boron (B) 0.3 ppm 0.3 ppm
Copper (Cu) 0.05 ppm 0.05 ppm
Molybdenum (Mo) 0.05 ppm 0.05 ppm
Sulfates (SO4) 20 ppm 20 ppm
Chloride (Cl) <300 ppm <300 ppm
Sodium (Na) <100 ppm <100 ppm

Concentrations in parts per million (ppm) at the dripper. Micronutrients are in shaded boxes. (*) See below for explanation on blossom end rot.

 

Like all nutrient recipes the numbers in Table 1 are a starting point that will need to be adjusted depending on the local environment (temperature, humidity, solar radiation and water quality) and the different salt accumulations that occur in normal conditions depending on the absorption by any given strain of pepper. Note that the ammonium (NH4) levels for young and mature plants are very low compared to nitrates. Ammonium is not necessary depending on the substrate included for pH buffering.

Note also that chloride and sodium have upper ranges. These two are considered contaminants even if they have nutritional value for the plants. They are generally present in the water and their requirements are very low similar to micronutrients.

 

Preventing blossom end rot

Bell peppers’ most common physiological problem is blossom end rot, which is generally due to a water stress preventing the internal transport of calcium. It is common to increase the concentration of calcium ions in the solution together with chloride, phosphate and boron while reducing potassium to promote the absorption of calcium during potential blossom end rot periods, particularly during hot summers (* in Table 1).

 

The most common chemicals for mixing nutrient solution are the following:

Ca(NO3)2 (Calcium nitrate)

KNO3 (Potassium nitrate)

KH2PO4 (Monopotassium phosphate)

MgSO4*7 H2O (Magnesium sulfate)

H3BO3 (Boric acid)

MnCl2*4 H2O (Manganous chloride)

CuCl2*2 H2O (Cupric chloride)

K2SO4 (Potassium sulfate)

MoO3 (Molybdenum trioxide)

ZnSO4*7 H2O (Zinc sulfate)

Fe 330 – Sequestrene (chelated iron)

Commonly in hydroponic production, chemicals are mixed in concentrated solutions to be diluted at the time of irrigation. The drawback of this fertilization method is that some of the chemicals present will precipitate out and be removed from the nutrient solution and need to be kept separate in at least two reservoirs. As a common rule, calcium needs to be separated from phosphates and sulfates to prevent precipitation.

 

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Are you maintaining the proper oxygen levels in your hydroponic production system?

Growers have affordable options for ensuring plants receive sufficient oxygen in hydroponic production systems to maximize growth and to reduce the chances of disease.

 

Oxygen is critical in the development and growth of edible crops grown in hydroponic systems such as nutrient film technique (NFT) and deep water raft culture. Tyler Baras, special projects manager at Hort Americas, is studying methods of adding oxygen to both conventional and organic hydroponic production systems in the company’s 12,000-square-foot research and demonstration greenhouse in Dallas, Texas.

“One of the big differences is how growers add oxygen,” Baras said. “A lot of times in conventional hydroponics, growers use air pumps and air stones to add oxygen. In organic systems these tend to be hot spots for biofilm development. We have removed all air pumps and air stones from the organic systems we are trialing.

Tyler Baras, special projects manager at Hort Americas, is studying methods of adding oxygen to both conventional and organic hydroponic production systems.
Photos courtesy of Tyler Baras

 

In the conventional production systems Baras is studying he has installed water pumps with a Venturi attachment to add oxygen to the nutrient solution reservoir.

“The pumps aren’t injecting air into the irrigation lines, but simply into the reservoir to circulate the water and to create a circular flow within the fertilizer reservoir,” he said. “As the pumps operate they draw in air through a ¼-inch emitter. There is the benefit of moving around the solution and the air being drawn in increases the level of dissolved oxygen.”

A method that organic growers use to increase oxygen levels is cascading the water when it returns to the reservoir. As water returns it is allowed to fall and break the surface of the reservoir so that the water can pull in oxygen.

“This can also be done in vertical farms where the water will fall down large return pipes to the reservoir,” Baras said. “This can happen in multiple stages where the water will drop several times. This is an effective method for increasing dissolved oxygen.

“For NFT, it appears more oxygen can be delivered to plant roots when the flow rate is increased per channel. As the flow rate increases, more oxygen is delivered to the roots so water isn’t sitting in the channel as long. This allows freshly oxygenated water to be delivered quickly to the roots. In conventional hydroponic NFT systems the flow rate is about ½ liter per minute. In our hydroponic NFT system I have been aiming for about 1-2 liters per minute.”

 

Adequate oxygen levels

Baras said oxygen is necessary for plant roots to perform metabolic processes.

“Most of the water uptake in plants is passive,” he said. “But there is a stage where the plants use energy to actively pull up water through the roots. This requires oxygen. If there isn’t any oxygen in the root zone no water will make it up through the roots to the top of the plant. Low oxygen in the root zone can appear as wilting at the top of the plants. This can seem counterintuitive in a hydroponic system because the roots are sitting in water, but the tops of the plants look like their wilting if there isn’t any oxygen in that water.”

As the flow rate increases in a NFT system, more oxygen is delivered to the roots so water isn’t sitting in the channel as long.

 

Baras said the need for oxygen in an organic hydroponic system is even more important because of the presence of living microbes in the fertilizer solution reservoir.

“These microbes also require oxygen,” he said. “The oxygen demand is often higher in organic systems than conventional systems because not only do the plant roots need oxygen, but the microbes need oxygen as well. In an organic hydroponic system one of the best ways of keeping biofilm in check is to keep the beneficial microbes happy.”

Baras said most of the oxygen measurements he has been taking in his research have been showing very similar oxygen levels for both conventional and organic production systems when the crops are performing well.

“I have been aiming for a level of 7-12 parts per million (ppm) dissolved oxygen, but generally the readings fall between 7-9 ppm,” he said. “I’m using a ProODO meter from YSI that is a very sensitive piece of equipment that accurately measures dissolved oxygen.”

Although most hydroponic growers are concerned with maintaining adequate oxygen levels, Baras said if too much oxygen is added to the solution it can cause root stunting.

“I haven’t reached that threshold yet in my trials,” he said. “It’s crop dependent on what that level is. When there is too much oxygen the roots have less motivation to grow larger because they are getting everything they need with a smaller surface area. That can then translate to the plants producing less biomass resulting in less leaf tissue. So at some point too much oxygen can actually cause less growth. For crops like tomatoes, peppers and cucumbers the whole plant would be stunted.

“The only way growers could reach excessive oxygen levels that damage the plants are when liquid oxygen or possibly ozone is used. Using air pumps or air stones to add oxygen, the levels won’t be high enough to stunt plant growth. To reach higher oxygen levels of 15-16 ppm, a grower would have to use other methods like liquid oxygen and ozone. It’s very difficult to reach high oxygen levels above 10 ppm unless an alternative method is used beyond air pumps, Venturis and cascades. I haven’t seen any growers go much higher than 8-9 ppm using the conventional methods.”

Baras said growers using a deep water raft system could try increasing turbulence in the pond to increase oxygen level. However, too much turbulence can sometimes cause damage to the roots.

Increasing turbulence in a deep water raft system can increase the oxygen level. But too much turbulence can damage roots.

 

“The roots in the turbulent areas are the ones that often times grow poorly,” he said. “The plants that are near the irrigation outlets where the currents are stronger, they have the poorest root growth. Sometimes growers will use air pumps in their ponds and those plants directly above where the air stones are located grow poorly.”

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

 

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.