Irrigation frequency and nitrogen fertilizers modify cotton yield at Emerald, central Queensland
1993
Ockerby, S.E. (Queensland Dept. of Primary Industries, Ayr (Australia)) | Lyons, D.J. (Queensland Dept. of Primary Industries, Indooroopilly (Australia)) | Keefer, G.D. (Unaffil.) | Blamey, F.P.C. (Queensland Univ., St Lucia (Australia). Dept. of Agriculture) | Yule, D.F. (Queensland Dept. of Primary Industries, Rockhampton (Australia))
Four irrigation frequencies and 6 nitrogen (N) fertilizer rates (0-300 kg per ha) were applied to cotton grown on 3 Vertisols. Lint yield was greatest when the plant available water before irrigation was 50-80 percent of the plant available water capacity (PAWC) of each soil. The rate of N fertilizer for maximum yield varied with plant available water and soil type. Plant available water before irrigation greater than 60 percent and less than 37 percent PAWC, and rain after irrigation reduced the crop N content at the time of maximum leaf area index. Relative yield generally responded to 130 kg crop N per ha, although the range from 101 to 141 kg crop N per ha reflected differences in the maximum yield of each treatment. If the crop N content was greater than 130 kg N per ha, yield and efficiency of crop N use for lint production was determined by the plant available water before irrigation and soil type. Nitrogen fertilizer strategies to achieve the maximum yield of cotton (var. Deltapine 61) should focus on obtaining 130 kg crop N per ha. This crop N content produced maximum yields for a range of plant available water contents before irrigation, and for three soil types.
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