|Delhom, Christopher - Chris|
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2017
Publication Date: 8/1/2017
Citation: Sui, R., Byler, R.K., Delhom, C.D. 2017. Effect of nitrogen application rate on yield and quality in irrigated and rainfed cotton. Journal of Cotton Science. 21:113-121.
Interpretive Summary: Under-fertilization or over-fertilization with nitrogen (N) can cause negative affect on desired growth pattern of cotton plants. Water stress in cotton plants can limit the plant growth and productivity, resulting in reduction of yield and quality. Research to understand the effect of fertilizer application rate and water stress on cotton yield and quality is necessary for optimal crop nutrient and water management. Scientists at USDA ARS Crop production Systems Research Unit and Cotton Ginning Research Unit, Stoneville, MS, and Cotton Structure and Quality Research Unit, New Orleans, LA, conducted experiments investigating the effects of N fertilization on yield and fiber quality in irrigated and rainfed cotton. A quadratic relationship between cotton yield and N fertilizer application rate was found. As yield reached its plateau, over-use of N fertilizer resulted in loss of yield and fiber quality. Irrigation increased cotton lint yield by 26% and fiber length by 2%. Irrigation could improve plant capability in utilizing the applied N fertilizer. Information obtained from this study can be used for optimization of nutrient and water management in cotton production.
Technical Abstract: Studies on the effect of nitrogen (N) application rates on lint yield and fiber quality in irrigated and rainfed cotton were conducted for two years in a humid climate. In 2013, cotton was planted in 48 plots. 24 plots were irrigated and the other 24 pots were rainfed. Six N application rates (0, 39, 67, 101, 135, and 168 kg/ha) with 4 replicates were randomly assigned to the irrigated and rainfed plots. In 2014, five N treatments (0, 56, 112, 168, and 224 kg/ha) with 4 replicates were assigned to 20 plots. All plots in 2014 were irrigated. The irrigation was scheduled based on soil water content measured using soil moisture sensors. Cotton leaf samples were collected at peak bloom stage and analyzed for leaf N content. Lint cotton yield and fiber quality were determined. Relationship among N application rate, leaf N, lint yield, and fiber quality was statistically analyzed. Effect of N application rates on cotton lint yield was significant in 2014 (p=0.0196), but not in 2013. In 2013, leaf N content varied in a range of 1.72% to 4.37% with a mean of 3.53% in irrigated cotton, and 2.47% to 4.14% with a mean of 3.36% in the rainfed cotton. In 2014, leaf N content varied from 1.77% to 4.28% with a mean of 3.51%. Yield showed a quadratic relationship with leaf N content in irrigated cotton in both 2013 (p=0.0268) and 2014 (p=0.0099). Correlation between leaf N and yield of rainfed cotton was not significant in 2013. Leaf N of irrigated cotton in 2014 had significant correlation with fiber length (p=0.0037), UQL (p=0.0001), and UHML (p<0.0001). Yellowness was linearly related with Leaf N content. Fiber strength showed a linear relationship with leaf N in 2013 rainfed cotton (p=0.0495), a quadratic relationship with irrigated cotton in 2013 (p=0.0231) and 2014 (p=0.0365). Overuse of nitrogen fertilizer in cotton could result in loss of yield and fiber quality. When the fiber quality from irrigated cotton was compared with rainfed cotton, irrigation increased lint yield by 26% and fiber length by 2%.