Author
|
Submitted to: Soil Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/14/2005 Publication Date: 8/31/2005 Citation: Smith, D.R., Moore Jr, P.A. 2005. Soil extractable phosphorus changes with time after application of fertilizer: 2. manure from swine fed modified diets. Soil Science. 170(8):640-651. Interpretive Summary: Recent studies have suggested that some best management practices, such as dietary modification, used to reduce phosphorus in manure may increase phosphorus runoff from pastures fertilized with this swine manure. This study was conducted to determine if there were any effects on soluble phosphorus, or soil test phosphorus with time due to fertilization with manure from dietary modification or manure amendment treatments. High and low soil test phosphorus soils were fertilized with swine manure from two diet regimes and two manure treatment regimes. After fertilization, the soils were incubated, and samples were analyzed at 0, 2, 4, 8, 12 and 16 weeks. Soluble, Mehlich 3, and Morgan phosphorus tended to decrease with time. Olsen extractable phosphorus tended to increase for the first four weeks, after which levels decreased to those levels observed in the initial measurements. High soil test phosphorus soils resulted in higher phosphorus values than low soil test phosphorus soils. Swine manure from phytase diets resulted in higher phosphorus in all the extractions throughout the 16 week study. Utilization of chemical manure amendments (aluminum chloride) reduced phosphorus levels in soils as well. This research impacts land managers and manure management planners by providing information needed to assist them in planning for the application of manure to fields, and how manure amendments and dietary modification will impact the long-term ability of soils to receive swine manure applications. Technical Abstract: Recent studies have suggested that some best management practices, such as dietary modification, used to reduce phosphorus (P) in manure may increase P runoff from pastures fertilized with this manure. The objectives of this study were to determine if there were any effects on soluble P, or soil test P (STP) with time due to fertilization with manure from dietary modification or manure amendment treatments. High and low STP soils were fertilized with swine manure from two diet regimes (normal and phytase) and two manure treatment regimes (control and with aluminum chloride treatment). After fertilized, the soils were incubated, and samples were analyzed at 0, 2, 4, 8, 12 and 16 weeks. Soluble, Mehlich 3, and Morgan P tended to decrease with time. Olsen extractable P tended to increase for the first four weeks, after which levels decreased to those levels observed in the initial measurements. High STP soils resulted in higher P values than low STP soils. Swine manure from phytase diets resulted in higher P in all the extractions throughout the 16 week study. Utilization of chemical manure amendments (AlCl3) reduced P levels in soils as well. A P sorption ratio (PSR) was calculated for each soil, and treatment of manure with AlCl3 resulted in reduced PSR compared to untreated manure. Addition of AlCl3 treated swine manure to high STP soil resulted in PSR values similar to unfertilized soil, indicating a reduced potential for P losses in runoff. This research impacts land managers and manure management planners by providing information needed to assist them in planning for the application of manure to fields, and how manure amendments and dietary modification will impact the long-term ability of soils to receive swine manure applications. |
