Corn response to starter fertilizer and tillage across and within fields having no-till management histories

Corn (Zea mays L.) early growth often is slower in no-tilled than tilled soils. Starter fertilization usually increases early plant growth but has inconsistent effects on grain yield. This study assessed (i) starter and tillage effects on corn grain yield, dry weight (DW), and N, P, and K uptake at the V5-V6 stage and (ii) the within-field variation of responses. Seven replicated strip trials were conducted on fields previously managed with no-tillage using yield monitors and global positioning systems (GPS). Treatments were no-starter and liquid starter with or without tillage and were applied in addition to farmers' normal broadcast NPK rates. Starter applied 3.9 to 27.2 kg N ha(-1), 5.2 to 24.2 kg P ha(-1), and 0 to 4.1 kg K ha(-1) across fields. The tillage treatment was spring disking or strip tillage. Tillage increased (P less than or equal to 0.05) yield in four fields (210-500 kg ha(-1)), starter increased yield in three fields (93-522 kg ha(-1)), and both treatments usually increased DW and nutrient uptake. There were no treatment interactions. Tillage and starter fertilization did not influence yield variability but increased DW and nutrient uptake variability. Soil test results (P, K, pH, and organic matter) or soil series could not always identify fields where starter would increase yield. However, in two fields, starter increased yield only in areas with Bray-1 soil P < 16 mg P kg(-1). On average, tillage increased yield 2.5%, starter increased yield 1.1%, and DW or nutrient uptake responses to either treatment were 20 to 30%. Large DW and nutrient uptake responses to starter did not translate into large or frequent yield responses.