Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: October 25, 2001
Publication Date: N/A
Effective utilization of animal manures as a crop nutrient source is limited by the amount and timing of nutrient release from the applied manure. The objective of this study was to measure changes in P availability in soils treated with manures or commercial fertilizer. Fifteen soils were collected to represent a wide range of chemical and physical properties and cropping history. Beef manure, dairy manure, swine effluent, turkey litter, or fertilizer (ammonium polyphosphate) were added to soils at a target rate of 56 kg P/ha for a total of 26 soil/treatment combinations. The amended soils were aerobically incubated under thermal regimes simulating seasonal changes in soil temperature. Soil samples were analyzed for available P (Bray 1, Mehlich 3, Olsen) and water-soluble P at 2, 4, 6, 9, 12, 24, and 52 weeks. Trends in P availability varied significantly among treatments and among soil tests. Average P availability ranged from <10% to >90% across all treatments. Results suggest that accurate recommendations for utilizing animal manures as a P source must consider soil-, manure-, and soil test- specific information. More general recommendations for P availability from animal manures based on soil testing may not be attainable.