Corn Yield Response to Nitrogen Rate and Timing in Sandy Irrigated Soils
2005
Gehl, Ronald J. | Schmidt, John P. | Maddux, Larry D. | Gordon, W Barney
Efficient use of N fertilizer for corn (Zea mays L.) production is important for maximizing economic return and minimizing NO₃ leaching to groundwater. The objective of this study was to evaluate grain yield response to irrigation rate and N rate and timing for irrigated corn in the sandy soils along major Kansas waterways. Nitrogen treatments included 300 and 250 kg N ha⁻¹ applied at planting; 250 kg N ha⁻¹ applied at planting (one-half) and sidedress (one-half); 185 kg N ha⁻¹ applied at planting (one-third) and sidedress (two-thirds); 125 kg N ha⁻¹ applied at planting (one-fifth) and sidedress (two-fifths, two-fifths); and 0 kg N ha⁻¹ Nitrogen treatments were duplicated at one site for each of two irrigation treatments (IS): 1.0× (optimal) and 1.25× (25% > optimal). A split application of 185 kg N ha⁻¹ was sufficient to achieve maximum corn yield at every location, and in most instances 125 kg N ha⁻¹ was sufficient. These rates were on average 88 kg N ha⁻¹ less than the current N recommendation for corn in Kansas, indicating that N rates could be reduced for these soils by an average of about 40% of the current N recommendation when N is split applied. The environmental risk associated with irrigated corn production on these sandy-textured soils, specifically, NO₃ leaching to groundwater, will be minimized only when N fertilizer and irrigation inputs do not exceed crop requirements and N fertilizer is applied to more closely match crop demand (e.g., in-season applications).
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