Response of Dryland Cotton Plant Growth, Soil-water Uptake, and Lint Yield to Two Extreme Types of Tillage

Better soil management prior to dryland cotton growing is not or hardly rewarded by a higher cotton lint yield production in a semi-arid climate. More information about the soil moisture depletion pattern of dryland cotton on different tillage practices is needed. The purpose of this study was to evaluate the influence of differences in soil-water stress in the root zone with time as a result of tillage practices on growth and yield of a dryland cotton crop. The soil-water interaction patterns of roots of dryland cotton (Gossypium hirsutum L.) on two extreme types of tillage practices were studied in a field experiment with six replications per tillage treatment. The two tillage practices were plowing to a depth of 40 cm and a no-tillage disking prior to the cotton growing season. Cotton was grown in a 2-year rotation of dryland cotton and winter wheat (Triticum aestivum L.) Soil conditions created by the two tillage practices resulted in a denser and deeper root system of plants on plowed soil than on minimum-tilled soil. Above-ground vegetative growth of plants on plowed soil was more extensive and prolonged than of those on minimum-tilled soil. Final lint yields of the crops on the two tillage treatments did not differ in the two seasons of study. Plants on plowed soil showed an increasing extraction rate resulting in a peak moisture stress in the reproductive stage. A relative-constant rate was found for plants on minimum-tilled soil in the period from emergence to early plowing and a moisture-stress-induced termination of the vegetative growth. It was indirectly inferred that differences in growing behavior and the similarity in lint yield of plants grown on plowed and minimum-tilled soil were related to differences in magnitude and occurrence of soil moisture stresses developed in the root zone during the vegetative and reproductive stages of the cotton plant.