CORN HYBRID RESPONSE TO STARTER FERTILIZER IN A NO-TILLAGE, DRYLAND ENVIRONMENT

A dryland corn (Zea mays L.) production system that has gained popular ity in Kansas involves planting as early in the spring as possible so that pollination occurs under more favorable moisture and temperature conditions. Cool soils that occur with early planting in high-residue production systems can reduce nutrient uptake. Starter fertilizer appl ications have been effective in enhancing nutrient uptake even on soil s high in available nutrients. Corn hybrids may differ in their respon se to starter fertilizer. The objective of this study was to evaluate corn hybrid response to starter fertilizer in a no-tillage, dryland en vironment. This field experiment was conducted from 1993 to 1995 at th e North Central Kansas Experiment Field, located near Belleville, on a Crete silt loam soil (fine, montmorillonitic, mesic Pachic Arguistoll ). Treatments consisted of five corn hybrids and two starter fertilize r treatments. Fertilizer treatments were starter fertilizer (30 Ib N a nd 30 Ib P2O5/acre) or no starter fertilizer. Starter fertilizer was a pplied 2 in. to the side of and 2 in. below the seed at planting. In a ll 3 yr of the experiment, grain yield, maturity, and total P uptake ( grain plus stover at maturity) were affected by a hybrid x starter fer tilizer interaction. Starter fertilizer consistently increased yields, reduced the number of thermal units needed from emergence to midsilk, and increased total P uptake of Pioneer 3346, Dekalb 636, and Dekalb 591, but had no effect on ICI 8599 and Pioneer 3563. When averaged ove r the 3 yr of the experiment, starter fertilizer increased grain yield of responding hybrids (hybrids in which the 3-yr average yield was in creased by the use of starter fertilizer) by 13 bu/acre. Starter ferti lizer increased V6 stage above ground dry matter production and N and P uptake of all hybrids evaluated. Far leaf N and P concentrations als o were increased by starter fertilizer, regardless of hybrid. Results of this work show that starter fertilizer can increase grain yield and be feasible for some hybrids, whereas yields of other hybrids are not affected.