|Sauer, Thomas - Tom|
Submitted to: Animal, Agricultural and Food Processing Wastes Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/11/2000
Publication Date: N/A
Technical Abstract: Recent state and federal guidelines regarding land application of animal wastes have focused on defining threshold soil test phosphorus (STP) levels above which further waste application is limited or prohibited. The objective of this research project is to develop a model for predicting STP trends in fields receiving animal wastes. The model is designed to be used as a planning and management tool for identifying the land base necessary to assimilate phosphorus from animal feeding operations (AFOs) while maintaining STP values below threshold levels. Simulations completed for a typical broiler production operation in the Ozark Highlands (4 broiler houses with litter applied to 65 ha. of permanent pasture) indicated that the 336 kg ha**-1 (300 lbs A**-1) STP threshold could be reached in less than 20 years. Similar predictions for a typical swine farrowing operation indicated an even faster approach to the threshold STP level. Options simulated for reducing phosphorus accumulation included removal of forage as hay and the use of phytase enzyme and/or high available phosphorus (HAP) corn in the animal diets to reduce excreted phosphorus. These techniques were all shown to be effective in slowing the increase in STP but the ratio of animal units to land base was still key to the long-term sustainability of the AFOs. Current modeling efforts focus on expanding the model to row crop systems and other types of waste materials.