Laura Avila, Univ of Florida, Agronomy Dept, 304 Newell Hall, Gainesville, FL 32611, Lincoln Zotarelli, Univ of Florida, PO Box 110965, Gainesville, FL 32611-0965, Johannes Scholberg, Univ of Florida, 304 Newell Hall, Gainesville, FL 32611-0500, and Corey Cherr, Univ of California, 402 One Shields Ave, Davis, CA 95616.
Sandy soils are prone to nitrogen leaching and use of cover crops (CC) has been documented to play an important role in enhancing nutrient retention. Use of leguminous CC may supply additional N via symbiotic N fixation thereby reducing external N-fertilizer requirements of sweet corn. The objective of this study was to determine the contribution of rye, vetch, and rye/vetch mix to N nutrition and yield of sweet corn. Spring-grown sweet corn followed either a winter fallow (F), vetch (V), rye (R) or a different hairy vetch/rye mixes (70HV+30R vs 30 HV+70R). Sweet corn in CC-based systems were amended with either 0, 67 or 133 kg N/ha (denoted as: CC0, CC67, and CC133). Non-CC (control) plots receiving 0, 67 133, 200 or 267 kg N/ha were also included in order to develop a N response curve. Fertilizer was applied after emergence, 5-leaf stage and prior to tasseling. During 2006,15N was also used to enhance our understanding of how N form and application time, affects fertilizer-N uptake efficiency (FUE). Total CC biomass accumulation was greater in mixed CC systems where as N accumulation by vetch was much higher compared to rye. Corn growth and N accumulation increased with N rate and was greater for CC-based systems. Overall FUE decreased with N rate while N utilization from CC residues was relatively low, possibly due to poor synchronization between N release by CC and sweet corn N uptake dynamics. Overall corn yields were 10.3 and 7.5 Mg/ha for CC-based and winter fallow system, respectively. The contribution of CC residues to the corn was equivalent to 59 kgN/ha for the CC0 treatments. Total ear yield for the CC67 and CC133 treatments were 10.4 and 16.5 Mg/ha, respectively. However, non-CC systems receiving 200-267 kg N/ha still had the highest (18.3 and 20.8 Mg/ha) yield.
Recorded presentation