Organic Fertilizers in Alabama: Composition, Transformations, and Crop Response in Selected Soils of the Southeast United States

Rapid growth in organic production in the past 20 years is due to consumer concerns about the impacts of conventional agriculture on the environment, food safety, and quality. There are considerable variations in nutrient concentration and the rate of mineralization among organic fertilizers. Some organic fertilizers and application rates are specific to soil types, which affect the nutrient potential. Two organic fertilizers produced in Alabama and added to soils are the chicken or poultry litter (1.8 million Mg annually) and the hydrolyzed liquid fish protein. The underor overestimation of the total N content of the litter may result in its overor underap‐ plication with potential environmental consequences to surface waters. The overesti‐ mation of the total N may result in its inadequate application. The inorganic forms (ammonium, NH4–N; nitrate, NO3–N; and nitrite, NO2–N) are found in small but sometimes significant amounts especially when broiler litter is stored under environmental conditions favorable to nitrification. Limited information is available on the usefulness of the various modifications of the regular Kjeldahl method in poultry litter analysis and transformations when added to soils. This chapter provides information and our experiences on the sources of organic fertilizers produced in the southeastern United States (Alabama).