Phosphorus Fertilization in No-Tillage Corn Production

The use of no-tillage crop production as a water quality management practice may be complicated by a tendency for phosphorus (P) to accumulate at or near the soil surface under no-tillage conditions. Little work has been published to define best management strategies for P in no-tillage situations, either from fertilization or water quality standpoints. In this study, P was applied to no-tillage corn (Zea mays L.) by surface broadcasting or subsurface banding, to a Wooster silt loam (fine-loamy, mixed, mesic Typic Fragiudalf) in northeastern Ohio at rates of 0, 14.5, and 29 kg P ha⁻¹, and to a London silt loam (fine, illitic, mesic Aquic Hapludalf) in southwestern Ohio at rates of 0, 19, 39, 58, and 116 kg P ha⁻¹. Soil test P levels were generally below sufficiency for maximum corn production at both sites. Over a 3-yr period at the Wooster site, both fertilized and unfertilized plots showed significant accumulations of P near the soil surface; however, subsurface banding reduced surface accumulation at the highest P rate. At both sites, banding P generally produced higher yields than broadcasting at equivalent rates. When yields, soil test P levels and fertilizer rates were fit to the Bray-Mitscherlich function, the resulting equations indicated greater fertilizer efficiency for band application. Comparison of equations derived from data in the present study with the equation used for making P fertilizer recommendations for conventional tillage in Ohio indicated the need for higher broadcast fertilizer rates in no-tillage and also a higher soil test P level for P sufficiency in no-tillage when compared with conventional. The advantages of banding and lower broadcast fertilizer use efficiency in no tillage seen in this study are contrary to conclusions drawn from previous studies dealing with no-tillage fertilization.