Water and nitrate movement in poultry litter amended soils

Nitrate leaching from land application of animal wastes has been linked to increasing levels of nitrate in drinking water in the Suwannee River Basin over the past several years. The main focus of this research study was to describe nitrate movement in soils under long term poultry litter management. Pedo Transfer Functions (PTF) were developed to describe the water retention characteristics that are valued as low resource alternatives. The PTFs were found to be influenced by the clay content followed by the soil organic carbon content. Mineralization of poultry manure was determined in the laboratory columns during a 60-day incubation period. At the end of the 60-day period, 69, 51, 58, 47, 48, 43 and 39% of the total nitrogen applied was mineralized for applications equivalent to 3, 6, 9, 12, 15, 18 and 21 Mg ha-1 of poultry manure respectively.; LEACHM is a potential modeling tool for characterizing nitrate and water movement in the soils. A statistical procedure termed the "Scenarios Technique" was effectively combined with LEACHM to provide a predictive approach for nitrate losses from the drainage zone for various nutrient management levels. Higher N rates produced higher cumulative nitrate values in the soils. An application of additional 50 kg ha-1 N in the form of ammonium nitrate along with the standard litter application resulted in higher nitrate levels in the drainage indicating that the source of N was a critical factor when making nutrient management decisions. The scenarios established with a sequence of wet dry years had a strong effect on the nitrate leaching suggesting that the effect of adverse weather conditions on the nitrate leaching risk could be forecast with the help of the Scenarios Technique. The effect of textural changes in the soil profile on soil nitrate movement was less pronounced compared to the total rainfall received. The Scenarios Technique was found to be a reliable tool for evaluation of best nutrient management practices in Ultisols.