Manure History and Long-Term Tillage Effects on Soil Properties and Phosphorus Losses in Runoff
2003
Andraski, Todd W. | Bundy, Larry G. | Kilian, Kenneth C.
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.
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