Land grading is one of the technique facilitating to even moisturizing of irrigated field and decreasing irrigation rates. Modern applied design methods and technologies of land grading don’t account the subsidence of soil. The author has developed the technique for capital land grading at irrigated lands taking into account the soil subsidence and minimizing the volumes of earth works for different patterns of irrigated fields. On the base of developed technique the technology for land grading was improved. At the territory of the farm “Azamat tazhribakor” of the association of water users “Yangiabad” of the Syrdarya region three techniques for land grading were tested: 1) tillage, lazer land grading, filling, and cutting of soil, diagonal land grading; 2) deep subsoiling on diagonal of a field, lazer land grading, loosening on the opposite diagonal of a field, correcting land grading; 3) tillage, lazer land grading, deep subsoiling on the diagonal of the field, correcting land grading, loosening on the opposite diagonal of a field. As a result of analysis of technical and economic indicators, it was established that the second technique for land grading was the most effective. The developed technique for design of capital land grading provides reducing of the working time of designers in 4-6 times, and technology of its performance decreases the volumes of additional earth works up to 15 %. The field study shows that at the lands, where capital land grading were done, the loss of irrigation water decreases and coefficient of water-use efficiency increases by 20-40 %.
Keywords: lazer land grading, soil subsidence, crop yield, technology, irrigation water.
