Author
|
Submitted to: Soil Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/5/2005 Publication Date: 7/21/2005 Citation: Smith, D.R., Moore Jr, P.A., Miles, D.M. 2005. Soil extractable phosphorus changes with time after application of fertilizer: 1. litter from poultry fed modified diets. Soil Science. 170(7):530-542. Interpretive Summary: In recent years, research of phosphorus losses from pastures fertilized with poultry litter from modified diets has shown inconclusive results. This study was conducted to determine how poultry litter from birds fed modified diets, and alum treated poultry litter interact with soil. Poultry litter and inorganic fertilizer were added to soils that had either received manure for twenty years, or no phosphorus fertilization for ten years. Addition of inorganic fertilizer or poultry litter did increase the soluble and soil test phosphorus. Unlike inorganic fertilizer, addition of poultry litter resulted in increased soluble phosphorus in soils for four to eight weeks. There were no appreciable changes in Mehlich 3 phosphorus with time for the high soil test phosphorus soil. Use of phytase and/or high available phosphorus corn tended to result in slight to moderate reductions in phosphorus fractions, while addition of aluminum sulfate to poultry litter tended to result in significant reductions in extractable phosphorus. The phosphorus sorption ratio was increased by inorganic fertilizer and poultry litter, however use of high available phosphorus corn, phytase and alum together resulted in similar phosphorus sorption ratio values compared to unfertilized soils. This research impacts land managers and manure management planners in an improved understanding of how dietary modification and manure amendments affect soil test phosphorus, and confirmation that combining these practices can increase the longevity of soils to accept poultry litter as a fertilizer source without impacting the inherent susceptibility of soils to phosphorus losses. Technical Abstract: Recent studies have suggested that best management practices, such as dietary modification, used to reduce phosphorus (P) in manure may increase P runoff from land fertilized with that manure. This research was conducted to determine how litter from poultry fed modified diets and aluminum sulfate (alum) treated poultry litter impacted P in soils with time. Poultry litter from broilers fed four diets and inorganic fertilizer were added to high and low soil test P (STP) soils. Changes in soluble and STP were monitored for sixteen weeks. Litter and fertilizer treatments increased soluble P and STP fractions compared to unfertilized soils. Soluble P in soils increased up to week four following additions of poultry litter. There were no appreciable changes in Mehlich 3 P with time for the high STP soil. Use of phytase and/or high available P (HAP) corn tended to result in slight to moderate reductions in P fractions, while addition of alum to poultry litter tended to result in significant reductions in extractable P. The P sorption ratio (PSR) was increased by inorganic fertilizer and poultry litter, however use of HAP corn, phytase and alum together resulted in similar PSR values compared to unfertilized soils. The impact of this research is an improved understanding of how dietary modification and manure amendments affect STP, and to confirm that combining these practices can increase the longevity of soils to accept poultry litter as a fertilizer source without impacting the inherent susceptibility of soils to runoff P losses. |
