The Irrigation possibility of cotton with drip irrigation systems

This study was conducted to determine the possibility of irrigation of cotton with drip sytems. The research was carried out at the experimental area of the Department of Agricultural Structures and Irrigation of Çukurova University in 1994 and 1995. In the experiment, Çukurova-1518 cotton variety was planted. The laterals were placed at 0.7 m intervals (a lateral for every crop row). The amount of irrigation water applied was based on free surface evaporation from a screened Class-A Pan. Irrigation treatments consisted of two different irrigation intervals (II = 5; 12 = 10 days), and three plant-pan cofficients (Kcpl = 0.75, Kcp2 = 0.90, Kcp3 = 1.05) and two different wetted percentage (PI = 0.70 and P2 = based on cover percentage of crop). The first irrigation was applied when the available soil moisture in the 120 cm depth in the profile was at 40 % level. According to the results, seasonal irrigation water varied from 322 to 472 mm; seasonal Et varied from 449 to 615 mm; and the cotton yield varied from 1970 to 4220 kg per hectar. Although the effect of irrigation intervals and wetting percentages on cotton yield was not significantly different, in the first year plant-pan cofficients and in the second year, P-Kcp interaction were significantly different at 5 % among the treatments studied. The seasonal ky value of cotton was determined to be 0.70. Significant relationships between plant height, leaf area index (LAI), development of plant cover, dry matter both with irrigation water and evapotranspiration were determined. According to the treatments, effective root zone depth for cotton varied between 88 and 1 1 1 cm. Total water use efficiency (TWUE) and irrigation water use efficiency (IWUE) varied between 0.58-0.62 kg/da/mm and 0.755-0.94 kg/da/mm, respectively. The ratio of irrigation water to evapotranspiration (I/ET) was 67 - 72.5 %. It was determined that the salt accumulation at 15 cm distance from the dripper increased in upper layer gradually decreased towards the bottom. At a 30 cm distance from dripper, salt accumulation increased toward near the wetted front. The results revealed that cotton can be irrigated with drip systems using 10 day interval, Kcp : 1.00 and P : based on actual cover percentage of crop. Key Words : Cotton, drip irrigation, yield - response factor, root growth, irrigation program.