Chapter 5 - Potential of Management Practices and Amendments for Preventing Nutrient Deficiencies in Field Crops under Organic Cropping Systems

Abstract

Food produced in organic production systems is usually considered better for human health than that produced under conventional systems. Nutrient deficiencies are one of the major limiting factors for sustainable yields under organic cropping systems, because synthetic fertilizers/chemicals are not permitted. Application of compost/manure, alfalfa pellets, thin stillage, distiller grain, and fish food additive can provide nitrogen (N), phosphorus (P), and other nutrients lacking in the soil. Green manuring or crop rotations with legumes improve yields of the succeeding crops. Intercropping annual cereals/oilseeds with grain legumes and perennial forage grass–legume mixtures also provide beneficial effects on crop yields. Liming can reduce soil acidity and improve crop yields. Wood ash can boost yield of crops, by correcting P, sulphur (S), potassium (K), and micronutrients deficiencies and also by increasing pH of acid soils. Gypsum and rapid-release elemental S could be used to prevent S deficiency in organic crops. Organic amendments and crop management practices could increase input of crop residues to soil and thereby improve organic carbon (C) and N storage in soil, and also soil fertility. However, with compost/manure applied at rates much greater than the crop N requirements, or if deficiencies of other nutrients are not corrected, excessive nitrate-N can accumulate in the soil profile. Granular rock phosphate and/or Penicillium bilaiae have shown small but inconsistent effects on increasing labile P in soil and crop yields. In conclusion, organic producers may consider integration of crop management practices and amendments to improve soil quality and fertility to increase sustainability of organic crop production systems. Long-term studies are required to determine the feasibility of management practices and amendments for preventing nutrient deficiencies and contributing to sustainable production in organic cropping systems.