Starter fertilizer and planting date effects on corn rotated with cotton

Corn (Zea mays L.) has become an important crop used in rotation with cotton (Gossypium hirsutum L.) in the mid-South region of the USA, but there has been little research on cultural practices for corn in this cropping system. The objective of this study was to determine if starter fertilizer has beneficial effects on corn growth and grain yield at different planting dates, Starter fertilizer and planting date effects were evaluated for corn in field experiments on a Commerce silt loam (fine-silty, mixed, nonacid, thermic Aeric Fluvaquent) for 3 yr (1991 through 1993). Six hybrids were evaluated with two starter fertilizer treatments at four planting dates. Starter treatments were (i) ammonium polyphosphate (11-37-0 N-P-K) applied in-furrow and (ii) a control with no starter fertilizer. Planting dates were mid-March, early April, mid-April and late April or early May, Yield response to planting date was not consistent across years; in two of three years, however, planting later than early April decreased yield. The starter fertilizer increased grain yield in two of the three years. Yield response to starter fertilizer was not consistent across years, hybrids, or planting dates, The planting date x starter interaction for yield was significant in two of three years and the hybrid x starter interaction for yield was significant in one of three years. Starter fertilizer increased early-season plant height by 2 to 36% and increased grain yield across planting dates from 0.5 to 1.4 Mg ha(-1) in 1991 and 0.4 to 1.0 Mg ha(-1) in 1993. There was no yield response to starter in 1992. Application of starter fertilizer, averaged across hybrids and years, reduced harvest grain moisture 5% and days to silking by 3 to 5 d, In this mid-South study, in-furrow N-P starter fertilizer increased early-season corn plant height and grain yield and decreased the number of days to silking of corn rotated with cotton.