Phosphorus loss to runoff water twenty-four hours after application of liquid swine manure or fertilizer.
Phosphorus (P) added to soil from fertilizer or manure application could pose a threat to water quality due to its role in eutrophication of fresh water resources. Incorporating such amendments into the soil is an established best management practice (BMP) for reducing soluble P losses in runoff water, but could also lead to higher erosion. The objective of this study was to test whether incorporation of manure or fertilizer 24 h before an intense rain could also reduce sediment-bound and total phosphorus (TP) losses in runoff. A rainfall simulation study was conducted on field plots (sandy loam with 6-7% slope, little surface residue, recently cultivated) that received two application rates of liquid swine manure or liquid ammonium polyphosphate fertilizer, using either surface-broadcast or incorporated methods of application. Incorporation increased the total suspended solids (TSS) concentrations in runoff but mass losses were not affected. Incorporation also reduced flow-weighted concentrations and losses of dissolved reactive phosphorus (DRP) and TP by as much as 30 to 60% depending on source (fertilizer vs. manure) and application rate. Phosphorus is moved below the mixing zone of interaction on incorporation, and thus the effect of the amount and availability of P in this zone is more important than cultivation on subsequent P losses in runoff. Incorporating manure or fertilizer in areas of intense erosive rain, recent extensive tillage, and with little or no surface residue is therefore a best management practice that should be adhered to in order to minimize contamination of surface water. Results also show comparatively lower P losses from manure than fertilizer.
Tabbara
Hadi
H
USDA-ARS, Water Conservation Laboratory, 4331 E. Broadway Rd., Phoenix, AZ 85040, USA. Hadi.Tabbara@asu.edu
D000383:Agriculture; D000818:Animals; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D005068:Eutrophication; D005308:Fertilizers; D008372:Manure; D010758:Phosphorus / Q000032:analysis*; D011891:Rain; D013552:Swine; D014872:Water Movements; D014876:Water Pollution / Q000517:prevention & control
D005308:Fertilizers; D008372:Manure; D010758:Phosphorus