ABSTRACT
Cotton production on the Texas High Plains is limited first by the lack of an adequate water supply throughout the growing season. Approximately 40% of the area is capable of supplemental irrigation and then growing season length and soil nutrient supply become the major yield-limiting factors. We have been conducting production management research including row spacing, irrigation scheduling, and nutrient supply management for the past 10 years. The purpose of this paper is to evaluate the use-efficiency of various production inputs such as water, radiation, and N supply as affected by production systems. Reducing the row width from the traditional 1.0m (40 in) row spacing, resulted in increased light interception, increased growth rate, and total biomass production. No significant increase in total water use was observed between the row spacings. Therefore, water use efficiency was significantly increased with the narrow row spacing. The narrow row spacings intercepted more light at equivalent LAIs then the conventional row spacing; however, the amount of biomass produced per unit light intercepted was not improved. Nitrogen supply significantly improved water use efficiency reaching a maximum at 0.25 kg N ha-1 mm-1. Nitrogen supply did not improve radiation use efficiency. The results of these analyses indicate that cotton productivity can be greatly improved on the Texas High Plains when production inputs are managed properly.
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