Manure history and long-term tillage effects on soil properties and phosphorus losses in runoff.
Manure additions to cropland can reduce total P losses in runoff on well-drained soils due to increased infiltration and reduced soil erosion. Surface residue management in subsequent years may influence the long-term risk of P losses as the manure-supplied organic matter decomposes. The effects of manure history and long-term (8-yr) tillage [chisel plow (CP) and no-till (NT)] on P levels in runoff in continuous corn (Zea mays L.) were investigated on well-drained silt loam soils of southern and southwestern Wisconsin. Soil P levels (0-15 cm) increased with the frequency of manure applications and P stratification was greater near the surface (0-5 cm) in NT than CP. In CP, soil test P level was linearly related to dissolved P (24-105 g ha(-1)) and bioavailable P (64-272 g ha(-1)) loads in runoff, but not total P (653-1893 g ha(-1)). In NT, P loads were reduced by an average of 57% for dissolved P, 70% for bioavailable P, and 91% for total P compared with CP. This reduction was due to lower sediment concentrations and/or lower runoff volumes in NT. There was no relationship between soil test P levels and runoff P concentrations or loads in NT. Long-term manure P applications in excess of P removal by corn in CP systems ultimately increased the potential for greater dissolved and bioavailable P losses in runoff by increasing soil P levels. Maintaining high surface residue cover such as those found in long-term NT corn production systems can mitigate this risk in addition to reducing sediment and particulate P losses.
Andraski
Todd W
TW
Department of Soil Science, 1525 Observatory Drive, University of Wisconsin, Madison, WI 53706-1299, USA. andraski@wisc.edu
Bundy
Larry G
LG
Kilian
Kenneth C
KC
D000383:Agriculture; D001682:Biological Availability; D004784:Environmental Monitoring; D005308:Fertilizers; D008372:Manure; D010758:Phosphorus / Q000032:analysis* / Q000493:pharmacokinetics; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*; D003313:Zea mays
D005308:Fertilizers; D008372:Manure; D014873:Water Pollutants; D010758:Phosphorus