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Effects of nitrogen rates and cover crops on lint yield of Stoneville 825 cotton no-tilled into various mulches were investigated over seven years, 1982-87. A Lexington silt loam sail at Jackson, Tennessee, was used for this series of experiments. Randomized split-split plot designs were used each year. Main plots were nitrogen rates of 0, 34, 67 and 101 kg/ha. Subplots were no-cover (stubble from preceding cotton crop), small grain and legumes. Subplots were divided into eight rows of conventionally tilled and eight rows of no-tilled cotton. Nitrogen rates and tillage treatments remained constant on each plot during these experiments. Lint yields from no-cover plots receiving no nitrogen were erratic, but did not decline during seven years of continuous cotton and averaged 813 kg/ha, while plots fertilized with 34, 67 and 101 kg N/ha averaged 1001, 993 and 1015 kg/ha, respectively. Plots covered with small grain residue and no additional nitrogen, produced the lowest yield, but were very responsive to nitrogen fertilizer. Lint yields of vetch-covered plots were reduced by an application of 34 kg N/ha. Additional nitrogen resulted in further yield reduction. Seven-year lint yields averaged across all covers were 798, 896, 894 and 881 kg/ha for nitrogen rates of 0, 34, 67 and 101 kg H/ha, respectively. Nitrogen requirements for cotton no-tilled into old cotton stubble are similar to nitrogen requirements of conventionally-planted cotton. Our data indicate that cotton no-tilled into small grain residue requires more nitrogen, while cotton no-tilled into vetch required little or no nitrogen fertilizer. |
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©National Cotton Council, Memphis TN |
Document last modified Sunday, Dec 6 1998
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