Corn Hybrid Response to Nitrogen Fertilization in the Northern Corn Belt

Abstract

Recent research in the central Corn Belt showing that corn ( Zea mays L.) hybrids differed markedly in yield response to N fertilization has stimulated interest in the N response characteristics of widely‐grown hybrids in various production areas. However, little information is available on the importance of adjusting N application rates to improve yield or N fertilizer efficiency with specific hybrids. This study was conducted to determine if major differences in yield response to N fertilization exist among widely‐grown hybrids in the northern Corn Belt, and to evaluate potential differences in N response characteristics among these hybrids. Experiments were conducted on a Piano silt loam (Typic Argiudoll) in southern Wisconsin using a split‐plot treatment arrangement. Corn had been grown on the experimental sites since 1981. In 1985, subplot treatments were five 105‐ to 110‐day relative maturity (RM) hybrids (Pioneer 3747 and 3732, Mo17 × A634, A632 × LH38, and LH74 × LH51). The same five hybrids plus two 95‐ to 100‐day RM hybrids (Pioneer 3906 and 3737) were evaluated in 1986. Main plot treatments in both years were N rates of 0, 70, 140, and 210 lb N/acre broadcast applied as NH 4 NO 3 before planting. In both years, grain yields varied with N rate and hybrid, but similar N rates were needed to maximize yields of the hybrids studied. Most hybrids produced maximum yields of 160 to 170 bu/acre with 140 lb N/acre in 1985, and 180 to 200 bu/acre with 210 lb N/acre in 1986. These responses are in good agreement with current Wisconsin N recommendations for corn production. The percentage of total N uptake accumulated at the midsilk stage of growth varied among hybrids and years. Results obtained suggest that the percent of total N accumulated at midsilk is not a consistent hybrid characteristic and is likely influenced by annual climatic variability. Nitrogen utilization efficiency (grain produced per pound of N uptake) was similar for the hybrids studied. We conclude that the N fertilizer requirements of the hybrids evaluated in this study are similar and that yields of these hybrids will likely be maximized with currently recommended N rates.