Nutrient Solutions for Controlled Environment Agriculture Presented by Dr. Don C. Wilkerson, Professor & Extension Specialist (Emeritus) Department of Horticultural Sciences Texas A&M University College Station, Texas

Caliber Biotheraputics, College Station, Texas

Baron Justus von Liebig Darmstadt Germany May 12, 1803

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

C, H, O, Macro Nutrients N, P, K,

Ca, S, Mg, Secondary Nutrients

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

“They are essential because a plant deprived of any one of these elements would cease to exist. “ Substrate 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 without soil/substrate.

The Hoagland solution provides all of the essential nutrients for plant growth and is appropriate for a wide Dennis Robert Hoagland (1884-1949) 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.

Daniel I. Arnon (1910 - 1994) Basic Hoagland Solution:

Component Stock Solution mL Stock Solution/1L N 210 ppm K 235 ppm Macronutrients Ca 200 ppm 2M KNO 202 g/L 2.5 3 P 31 ppm 1M Ca(NO3)2•4H2O 236 g/0.5L 2.5 Iron (Sprint 138 iron S 64 ppm 15 g/L 1.5 chelate) Mg 48 ppm

2M MgSO4•7H2O 493 g/L 1 B 0.5 ppm

1M NH4NO3 80 g/L 1 Fe 1 to 5 ppm Mn 0.5 ppm H3BO3 2.86 g/L 1 Zn 0.05 ppm MnCl2•4H2O 1.81 g/L 1 Cu 0.02 ppm ZnSO4•7H2O 0.22 g/L 1 Mo 0.01 ppm 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 Nutrient Solution Optimization Knowing 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 • quality • Solution temperature • Environmental conditions (temperature/humidity) • Light • Carbon Dioxide levels Nutrient Solution Optimization Continued… • 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