Corn Hybrid Response to Starter Fertilizer Combinations

ABSTRACT

Research has shown that some corn (Zea mays L.) hybrids grown under reduced tillage conditions respond to starter fertilizer containing nitrogen (N) and phosphorus (P), while others do not. This research studied variability of responsiveness among corn hybrids to starter fertilizer containing a more complete complement of nutrients. The experiment was conducted from 1996 to 1998 on a producer's field near Scandia, KS, on a Carr sandy-loam soil (coarse-loamy, mixed, superactive calcareous, mesic Typic Udifluvents). The response of four corn hybrids (Pioneer 3563, Pioneer 3346, DeKalb 591, and DeKalb 646) to starter fertilizer combinations containing N, P, potassium (K), sulfur (S), and zinc (Zn) was evaluated. In all three years of the experiment, starter fertilizer containing N and P consistently increased grain yield, reduced the number of thermal units needed from emergence to maturity, decreased grain-moisture content at harvest, and increased total P uptake (grain plus stover at maturity) of Pioneer 3346 and DeKalb 591, but had no effect on Pioneer 3563 and DeKalb 646. Addition of S to the starter mix produced additional yield increases for Pioneer 3346 and DeKalb 591, whereas addition of K and Zn to the starter did not show any additional yield benefit for these two hybrids. Grain yield of Pioneer 3563 and DeKalb 646 was not improved by starter fertilizer, regardless of the elemental composition. When no starter fertilizer was applied, early-season root development was greater in Pioneer 3563 and DeKalb 646 than in the other two hybrids. However, the addition of starter fertilizer increased numbers of roots and depth of rooting in Pioneer 3346 and DeKalb 591 but had no effect on Pioneer 3563 and DeKalb 636. Results showed starter fertilizer benefited grain yield for two hybrids. Grain yield of the other two hybrids, however, was not influenced by starter, regardless of which nutrients were supplied. This response may be attributed to differences in root-growth characteristics of the hybrids. The two responsive hybrids did, however, yield an average of 0.75 mg ha^?1 greater than the two non-responsive hybrids. This result indicates it is unlikely that all of the yield loss from not using a starter can be avoided by hybrid selection.