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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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Calling CEA Enthusiasts

Experienced growers are in demand, and you can accelerate your indoor and greenhouse growing know-how at the University of Arizona Controlled Environmental Agriculture Center [UofA-CEAC] in Tucson, Arizona from June 5th – 12th, 2017 at our Hydroponic Crop Intensive Workshops.

Grab a vine and swing into the CEAC Greenhouses for what that the industry considers “a critical service in training tomorrow’s greenhouse experts [that] no other university within the USA can provide the same quality and expertise of service” – Wadsworth Controls.  This is the last opportunity in 2017 to attend both courses back-to-back to optimize your time away from home and increase your grower know-how under the direction of our hydroponic research specialists.

CEAC Intensive Workshops are intended for growers looking to quickly advance their skills as they relate to hydroponic tomato and lettuce cultivation.  These multiple day events feature over a semester’s worth of real university course content, hands-on work in the greenhouse, useful agenda items such as an engineering roundtable discussion, face-to-face time with experts on your special questions, and networking time with personal follow-ups.

 Why CEAC’s Hydroponic Intensive Workshops?

  • Education immediately meets application – CEAC’s unique facilities support a quality learning experience, where knowledge from classroom lectures is immediately applied in the greenhouse.
  • Substantial time for immersion – The length and thoroughness of CEAC intensive workshop is unmatched.  Tomato Intensive includes 4 ½ days & Lettuce Intensive includes 3 ½ days of instruction and training.
  • Experience yields efficiency – CEAC Intensive Workshops have been around for 10 years.  We’ve constantly improved the content and its delivery, based on feedback, in order to more effectively disseminate knowledge. With a database of 100’s of common questions and strategic delivery of content, we’re likely to address your questions naturally throughout the course.  In addition, the limited class size offers the opportunity to address some questions more specific to your operation.
  • Bigger questions?  Better answers! – Between the instructors, supporting faculty, and members of the Round-Table Greenhouse Design discussion, you can pick our specialist’s brains and pull from their tens of thousands of hours of real-life experience with hydroponic growing systems.

Registration is open but space is limited.  Reserve yours now and take advantage of savings when you register for the combined workshops!

More information on the course, instructors, registration, designated lodging, and a list of topics covered can be found on the Controlled Environment Agriculture Center’s website here:

http://ceac.arizona.edu/hydroponic-crop-intensive-courses