Abstract
Water scarcity is often a major limiting factor in cotton (Gossypium hirsutum L.) production, and sustaining productivity and profitability with limited water is a major challenge for the cotton industry. A good understanding of the magnitude, timing and spatial distribution of cotton soil water extraction is important for proper irrigation management, and for development of accurate crop models and decision support systems. The overall objective of this study was to evaluate the water extraction distribution of cotton under different irrigation regimes. Specific objectives were to quantify: 1) the depth of soil water extraction as a function of time, 2) the percent of seasonal water extraction from each soil depth, and 3) the relationship between depth of soil water extraction and canopy height. To meet these specific objectives, daily and seasonal cotton soil water extraction were determined from continuous records of water content in the soil profile measured from four irrigation treatments during a field experiment. We found that cotton extracted soil water from as deep as 150 cm, but the percent of seasonal extraction sharply decreased with soil depth. The top 50 cm soil layer accounted for 75% of the seasonal extraction and the top 80 cm, for 90%. We also found that from 32 days after sowing (DAS) to 100 DAS, the depth of soil water extraction increased linearly at a rate of 1.89 cm·day-1 or 2.36 times the increase in crop canopy height. These findings suggest that cotton producers should manage irrigations to maintain adequate moisture in the top 80 cm of the soil profile rather than relying on moisture stored deeper in the profile.
Highlights
Water scarcity is often a major limiting factor in cotton (Gossypium hirsutum L.) production
Specific objectives were to quantify: 1) the depth of soil water extraction as a function of time, 2) the percent of seasonal water extraction from each soil depth, and 3) the relationship between depth of soil water extraction and canopy height. To meet these specific objectives, daily and seasonal cotton soil water extraction were determined from continuous records of water content in the soil profile measured from four irrigation treatments during a field experiment
We found that cotton extracted soil water from as deep as 150 cm, but the percent of seasonal extraction sharply decreased with soil depth
Summary
Water scarcity is often a major limiting factor in cotton (Gossypium hirsutum L.) production. How to sustain or increase productivity and profitability with limited water is one of the biggest challenges facing the cotton industry in many areas of the world. This requires increasing the beneficial use of water, which implies producing more crop quantity and quality with the same amount or even less water. According to [1], increasing crop water productivity (CWP) requires increasing transpiration while minimizing unwanted water losses, exchanging transpired water for CO2 more efficiently in producing crop biomass, and converting more of the produced biomass into harvestable yield. They suggested that to improve CWP, the most promising and efficient proven techniques were the use of limited supplemental irrigation, to optimize the use of limited water, and the use of water harvesting, to improve farm income in drier environments
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