Corn Yield as Affected by Fertilization and Tillage System¹

Recent adoption of no‐tillage planting systems by many farmers has raised questions concerning comparative yields with conventional tillage systems and problems associated with nutrient absorption. No‐tillage systems generally require surface application of P and K, thus studies are needed to determine whether surface‐applied nutrients can supply plant needs. The objectives of this study were to determine 1) the desirability of applying P and K on the soil surface, 2) comparative yields between zero‐tillage and conventional‐tilled corn ( Zea mays L.) production systems, and 3) the movement of P and K into the soil profile. Two soil types, an Ipava and a Clinton silt loam, were selected for these studies. A completely randomized experimental design with four replications was utilized on each soil type. Soil samples were taken at four depths of the soil profile at initiation of the studies and again during the final year. Soils were analyzed for P and K in order to determine the movement of surface applications of these nutrients. Movement of P and K into the soil profile following surface application on untilled areas was slow with both nutrients—K moved more rapidly than P. Following 2 years without P or K, yield levels were restored on plots receiving one annual application of both nutrients. Average yields of corn were similar on both tillage systems on both soil types. Yield trials produced similar yields with conventional and with zero‐tillage systems, although some problems occurred with reduced‐tillage systems. Surface application of P and K was a satisfactory method of meeting the plant needs for these nutrients.