SUBSTANTIATION OF COTTON IRRIGATION REGIME ON MEADOW-ALLUVIAL SOILS OF THE KHOREZM OASIS

Abstract

The article provides a comparative analysis of the establishment of cotton irrigation regimes on irrigated meadow alluvial soils of the Khorezm region of Uzbekistan from a groundwater level of 2,0 - 3,0 m based on the methods of the Research Institute for Breeding, Seed and Agricultural Technology of Cotton Cultivation and FAO. Experiments on the irrigation regime of cotton were carried out with the following variants of irrigated soil moisture: 70-70-60%, 70-80-60% and 70-80-60% (increased irrigation rates by 30 %) Maximum field moisture capacity MFMC. To establish the irrigation regime for cotton according to the FAO method, the program CROPWAT and AquaCrop are used. The comparison of the results showed that, corresponding to the FAO method, the number of irrigations by 4-6 times more (given in small irrigation norm amounts that`s why numbers of watering multiplies) than by the method of the Research Institute for Breeding. The best results were obtained for creating a meliorative reclamative condition for the growth and development of cotton in the experimental plots, provided that the over-irrigation moisture in the soil was maintained at 70-80-60% of the Ultimate Field Moisture Capacity (UFMC). During the growing season, followings are necessary: light soil that was irrigated 6 times, in the cotton development phase according to the scheme 1-4-1, irrigation norms 437-825 m3/ha, irrigation norms 3641-3676 m3/ha, yield was 4.02 t/ha, an average mechanical structure of the soil must be irrigated 5 times, based on the 1-4-0 scheme, with irrigation norms of 494-664 m3/ha and irrigation norms of 3090-3133 m3/ha, yield 4.01 t/ha, heavy mechanical soil should be irrigated 4 times, corresponding to the scheme 1-3-0, with irrigation norms of 541-753 m3/ha and irrigation norms of 2766-2786 m3/ha, yield 3.93 t/ha. Compared with the production (control) option, the cotton yield was more than 0.98 t/ha, 0.93 t/ha and 0.88 t/ha.