Hailin Zhang Department of Plant and Soil Sciences Oklahoma State University Soil Physical and Chemical Quality and Management in Organic Production

What makes up soils? Sand Silt Clay

Soil Is a Living Body USDA

Soil Properties  Physical  Texture  Structure  Chemical  Fertility  pH  Soluble salts  Biological  Microorganism population-life in the soil

Clay Silty Clay Sandy Clay % Clay % Silt % Sand Loamy Sand Sandy Clay Loam Sandy Loam Sand Silt Loam Clay Loam Loam Silty Clay Loam Silt

Water holding capacity and movement NRCS

Improving Soil Physical Condition  Adding organic material  Adding gypsum for alkali soils

pH and Buffer Index n Soil pH is a measure of the acidity and alkalinity of the soil; n Nutrient availability is related to pH; n Crops can only grow well in certain pH ranges; n Liming is the most economical and effective method to raise soil pH

pH value defines relative acidity or basicity Very strong Strong Medium Moderate Slight Medium Strong Basic Acid Pure water Most productive soils Vinegar Lemon juice Ammonia cleaner

Apply lime well ahead of planting to correct soil acidity

NCa PMg KSKS 16 Essential Elements CHOCHOCHOCHO BClCuFe MnMoZn Essential Plant Nutrients

Negatively Charged Colloids Attract Cations K+K+ Ca ++ Na + Ca ++ H+H+ Mg Soil Colloid

Clay and Organic Matter Have Greatest Influence on CEC Clay meq/100g Organic matter meq/100g Organic matter has a higher CEC (cation exchange capacity) Organic matter has a higher CEC (cation exchange capacity)

Nutrient balance is the key for success Right nutrients Improper nutrients

Soil Soluble Salts Affect Plant Growth Normal EC (mmhos/cm) ESP % Saline Sodic Increased salt hazard 30 Saline-Sodic

Over Fertilization  Salts build up in the soil  Alters soil pH  Unbalanced growth  More vegetative, less reproductive growth  More disease and less winter hardy

Soil Tests Serve Two Basic Functions n Provide a starting point for developing fertilizer and liming program n Monitor nutrient level to keep the fertilizer program on track

Soil Tests at OSU RoutinepH Buffer Index NitrogenPhosphorusPotassium Secondary Nutrients SulfurMagnesiumCalcium MicronutrientsIronZincBoron Soil Organic Matter, Soil Texture, Soil Salinity Compost, Animal Manure, Irrigation Water

Summary n Soil properties are important for plant growth n There are 16 essential plant nutrients n Soil testing is important for successful organic production n An representative sample is needed to ensure reliable test results n Balanced fertilizer program is critical

Soil, Water and Forage Analytical Laboratory n