Nutrient Solutionsfor Controlled Environment Agriculture

Presented byDr. Don C. Wilkerson, Professor & Extension Specialist (Emeritus)

Department of Horticultural SciencesTexas A&M University College Station, Texas

Caliber Biotheraputics, College Station, Texas

Baron Justus von LiebigDarmstadt Germany May 12, 1803

German scientist in the mid-19th century, showed that nutrients are essential for plant life.

He stated, "We have determined that a number of elements are absolutely essential to plant life. They are essential because a plant deprived of any one of these elements would cease to exist.

16 - Essential Plant Nutrients:

Ca, S, Mg,

Fe, Zn, Mn, Cu, B, Mo, Cl

Macro Nutrients

Secondary Nutrients

Micro Nutrients

C, H, O, N, P, K,

“They are essential because a plant deprived of any one of these elements would cease to exist. “

Substrate Plant Nutrition Versus

Hydroponic Plant Nutrition

Substrate Plant Nutrition:

Measured as Cation Exchange Capacity (CEC)

Hydroponic Plant Nutrition:

Plant nutrients in the bulk solution.

Substrates (i.e. rockwool) primarily for anchorage.

Developing a

Hydroponic Nutrient Solution

• More Cost Efficient• More Precise Control of Plant Nutrition• Eliminates Substrates as Potential Source of

Contamination

Hoagland Solution The Hoagland solution is a hydroponic nutrient solution released by Hoagland and Arnon in 1938 and revised by Arnon in 1950. This solution is was among the first developed for growing plants without soil/substrate.

The Hoagland solution provides all of the essential nutrients for plant growth and is appropriate for a wide range of plant species. The solution described by Hoagland and Arnon in 1950 has been modified several times, mainly to add iron chelates for improved stability.

Dennis Robert Hoagland (1884-1949)

Daniel I. Arnon (1910 - 1994)

Component Stock Solution mL Stock Solution/1L

Macronutrients

2M KNO3 202 g/L 2.5

1M Ca(NO3)2•4H2O 236 g/0.5L 2.5

Iron (Sprint 138 iron chelate)

15 g/L 1.5

2M MgSO4•7H2O 493 g/L 1

1M NH4NO3 80 g/L 1

Micronutrients

H3BO3 2.86 g/L 1

MnCl2•4H2O 1.81 g/L 1

ZnSO4•7H2O 0.22 g/L 1

CuSO4•5H2O 0.051 g/L 1

H3MoO4•H2O or 0.09 g/L 1

Na2MoO4•2H2O 0.12 g/L 1

Phosphate

1M KH2PO4 (pH to 6.0) 136 g/L 0.5

Basic Hoagland Solution: N 210 ppmK 235 ppmCa 200 ppmP 31 ppmS 64 ppmMg 48 ppmB 0.5 ppmFe 1 to 5 ppmMn 0.5 ppmZn 0.05 ppmCu 0.02 ppmMo 0.01 ppm

Nutrient Solution OptimizationKnowing the nutrients required to grow plants hydroponically is only one aspect of successful crop production. Maximizing yield also requires additional optimization of the solution.

• Concentration to apply (ppm or EC)• Timing of application (stage/rate of

growth) • Source of nutrients to use• Water quality • Solution temperature • Environmental conditions

(temperature/humidity)• Light • Carbon Dioxide levels

• pH (5.5 – 6.5)• Buffer Capacity• Electrical Conductivity (salinity)• Temperature• UV Light• Availability/Solubility (Precipitation)• Concentrates (1:200) • Pre-Mixed vs Make Your Own

Nutrient Solution OptimizationContinued…