Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 21, 1997
Publication Date: N/A
Interpretive Summary: Cotton is again becoming a popular crop in the southeastern Coastal Plain because major insect problems can now be controlled and cotton prices are improving. Although rainfall amounts are high most years, irrigation often improves cotton yield and quality, which means higher prices when it is sold. Even though the amount of money received by a farmer for a crop is higher, it may not be profitable to irrigate if the costs for equipment, energy, and labor are too high. Most cotton is irrigated with sprinkler systems, which require high water pressure and high energy use. Microirrigation requires low water pressure and uses less energy but has high material costs because much of the system is normally replaced each year. If system parts can be used for several years or if less material is required microirrigation might be profitable for crops like cotton. Another place where savings can be made is the way in which nitrogen is applied and managed. Results for a 4-year experiment show that microirrigation tubes placed under alternate furrows (half as many tubes) produced as much cotton as where tubes were placed under every row. Also, one nitrogen management method produced the same amount of cotton all years with about 30 percent less nitrogen. Both of these results reduce production costs, which should help increase profits on cotton, and reduce the potential for environmental contamination
Technical Abstract: Wider spacing of microirrigation tubing and its use for multiple growing seasons could make microirrigation profitable for agronomic crops such as cotton. This technology also permits frequent application of sidedress nitrogen during the growth cycle which may reduce the total amount of nitrogen fertilizer required because the potential for nitrate loss through hleaching will be lowered. Two microirrigation tubing placements and three nitrogen sidedress methods were evaluated for cotton during 1991-1994. Two nitrogen sidedress methods were evaluated for a rainfall-only treatment. Lint yields were not statistically different for the lateral placements any year, but yields for irrigated treatments were significantly greater than rainfall-only yields in 1992 and 1993. There was no yield reduction any year for one nitrogen treatment although it received 30 percent less nitrogen than other treatments. These results indicate significant potential for reduced cost of microirrigation because there was no yield reduction for laterals under alternate furrows (wide spacing). Also, they suggest the potential for significant savings in nitrogen fertilizer applications and a reduced potential for nitrate leaching.