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 under- or overestimation of the total N content of the litter may result in its over- or underapplication with potential environmental consequences to surface waters. The overestimation 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)

Nitrogen Transformations in Broiler Litter-Amended Soils

Nitrogen mineralization rates in ten surface soils amended with (200 μg N g−1 soil) or without broiler litter were investigated. The soil-broiler litter mixture was incubated at 25±1∘C for 28 weeks. A nonlinear regression approach for N mineralization was used to estimate the readily mineralizable organic N pools (N0) and the first-order rate constant (k). The cumulative N mineralized in the nonamended soils did not exceed 80 mg N kg−1 soil. However, in Decatur soil amended with broiler litter 2, it exceeded 320 mg N kg−1 soil. The greatest calculated N0 of the native soils was observed in Sucarnoochee soil alone (123 mg NO3− kg−1 soil) which when amended with broiler litter 1 reached 596 mg N kg−1 soil. The added broiler litter mineralized initially at a fast rate (k1) followed by a slow rate (k2) of the most resistant fraction. Half-life of organic N remaining in the soils alone varied from 33 to 75 weeks and from 43 to 15 weeks in the amended soils. When N0 was regressed against soil organic N (=0.782∗∗) and C (=0.884∗∗∗), positive linear relationships were obtained. The N0 pools increased with sand but decreased with silt and clay contents

Insect Population Dynamics, Varietal Preference and Performance of Organic Bio-Pesticides

Abstract Organic farming prohibits use of synthetic agrochemicals and encourages use of Integrated Pest Management (IPM) methods. States in the Southeastern US generally lag behind the rest of the country in organic vegetable production partly because of high insect pressures that make it difficult to grow vegetables without pesticides. This study on summer squash (Cucurbita pepo), grown using organic management practices, was conducted at a research station located in Mills River, North Carolina. The objectives of the study were to assess insect population dynamics and to evaluate performance of three OMRI-approved bio-pesticides: Azadirachtin, Pyrethrin and Spinosad against major insect pests of three summer squash varieties (Gentry, Spineless Beauty, and Zephyr). The highest populations of leafhoppers and thrips were recorded in early and late July. Squash varieties significantly influenced the populations of leafhoppers, thrips, aphids, and cucumber beetles. Bio-pesticides performed similarly against the major insect pests of squash recorded in this study Keywords: Organic Summer Squash, Insect Pests, Bio Pesticides, Organic Farmin

The Biological Consequences of Kaolin Geophagia

Abstract Kaolin geophagia is associated with the relief of gastrointestinal distress, but it may also cause adverse health effects on the body. This study was designed to: assess kaolin composition; test if 129SvEv mice would consume kaolin and determine the consequences of consumption; and assess rotational stress modulation of consumption. Thirteen kaolin samples were purchased from Alabama and Georgia stores. Chemical and physical properties were characterized for each sample using a Munsell chart, pH meter, Energy Dispersive Spectroscopy, Transmission Electron Microscopy, Visible Near-InfraRed Spectra, and Inductively Coupled Plasma-Optical Emission Spectrometry. Kaolin was then given to mice as food supplements and consumption was determined by weight/volume consumed and recorded in 12 hour intervals. Soil physical/chemical, mouse hematological, blood chemical and kaolin consumption data suggested that kaolin contained various elements, and geophagia was not exacerbated by rotational stress. Keywords: Kaolin, Pica, Geophagia, Hematology, Compositio