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United States Department of Agriculture

Agricultural Research Service

Research Project: EFFICIENT AND ENVIRONMENTALLY SUSTAINABLE AGRICULTURAL WATER MANAGEMENT IN HUMID REGIONS Title: Corn yield response to nitrogen fertilizer and irrigation in the southeastern Coastal Plain

Authors
item Stone, Kenneth
item Camp Jr, Carl
item Sadler, Edward
item Evans, Dean
item Millen, Joseph

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 23, 2010
Publication Date: June 23, 2010
Repository URL: http://hdl.handle.net/10113/44314
Citation: Stone, K.C., Camp Jr, C.R., Sadler, E.J., Evans, D.E., Millen, J.A. 2010. Corn yield response to nitrogen fertilizer and irrigation in the southeastern Coastal Plain. Applied Engineering in Agriculture. 26(3):429-438.

Interpretive Summary: Traditional irrigation systems apply water at the same rate over an entire field. The site-specific irrigation allows precise amounts of water to be applied to specific areas where and when plants need them for optimal growth. An experiment was conducted to evaluate spatial management of both water and fertilizer on a site-specific irrigation system in Florence, South Carolina. Corn was grown in a field experiment using a center pivot irrigation system that had been modified to make site-specific applications of water and fertilizer during the period 1999-2001. Treatments included three irrigation regimes (0, 75%, and 150% of a base rate to maintain adequate soil moisture), four nitrogen fertilizer amounts (50%, 75%, 100%, and 125% of a base rate recommended for corn production), and with four replications. As expected, corn grain yields increased with irrigation and nitrogen fertilizer, but how the corn crop responded varied among the three years, probably because of differences in rainfall and solar radiation during the growing season. During the first year (1999), there was less response to nitrogen fertilizer than in the following years. In two of the three years, corn grain yield increased with increased nitrogen fertilizer. These increases were greater with irrigation than with only rainfall. A regression analysis was then used to evaluate the yield response to both fertilizer and water. For the rainfed only treatment, yield response to nitrogen fertilizer was linear in all three years. The yield response to nitrogen fertilizer for the combined irrigation treatments was quadratic in 1999 and 2000, and linear in 2001. These results should be helpful in developing management strategies and decision support systems for profitable management of water and nitrogen fertilizer on spatially-variable soils in the southeastern Coastal Plain while conserving natural resources and protecting the environment.

Technical Abstract: Availability of spatially-indexed data and crop yield maps has caused increased interest in site-specific management of crop inputs, especially water and fertilizer. As commercial equipment to implement site-specific applications of water and nutrients becomes available, crop response to variable inputs and decision support systems will be required to ensure profitable crop production while conserving natural resources and protecting the environment. Corn was grown in a field experiment using a center pivot irrigation system that had been modified to make site-specific applications of water and fertilizer during the period 1999-2001 on a site near Florence, South Carolina. Treatments included three antecedent crop rotations (prior four years), three irrigation regimes (0, 75%, and 150% of a base rate), and four nitrogen fertilizer amounts (50%, 75%, 100%, and 125% of a base rate), and with four replications. As expected, corn grain yields increased with irrigation and nitrogen fertilizer, but the nature of the response varied among the three years, probably because of differences in rainfall and solar radiation during the growing season. Also, there was less response to nitrogen fertilizer during the first year (1999), probably because of less solar radiation during grain fill and greater residual soil nitrogen from antecedent soybean crops. Corn grain yield increases from increased nitrogen fertilizer were greater with irrigation than with only rainfall in two years because of the greater range of fertilizer applied in the irrigated treatment. The response of yield increase from additional nitrogen fertilizer was greater for irrigated treatments than for rainfed treatments in 2000 only. The yield response to nitrogen fertilizer for the combined irrigation treatments was quadratic in form in 1999 and 2000, and linear in 2001. For the rainfed only treatment, yield response to nitrogen fertilizer was linear in all three years. Based on limited soil analyses, it appears that residual nitrogen in the soil profile was low each year. These results should be helpful in developing management strategies and decision support systems for profitable management of water and nitrogen fertilizer on spatially-variable soils in the southeastern Coastal Plain while conserving natural resources and protecting the environment.

Last Modified: 10/21/2014
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