GROWTH, DEVELOPMENT AND YIELD OF SUMMER GROWN SOYBEAN IN IRRIGATED SIEROZEM SOIL OF THE TASHKENT PROVINCE, UZBEKISTAN

Abstract

After independence of the Republic of Uzbekistan in 1991 there were drastic changes in farming system. Before the country independence, farmers in Uzbekistan had grown sole crop in a year such as cotton, maize and alfalfa. A number of crops are grown in cotton rotations rapidly increased to about 30 crops after the country independence. In the field experiment carried out in 2006 and 2007 in irrigated typical sierozem soil of the Tashkent Province we investigated possibility of obtaining two to three yields in a year and the crops impact on soil fertility. We found that summer cultivation of the double component crops (oats + green peas) and triple component crops (oats + green peas + rye) after winter wheat in the cotton-winter wheat based short rotations increased soil organic matter in the 0-30 cm soil layers from 0.014 to 0.037%, total nitrogen from 0.015 to 0.025%, and total phosphorus from 0.010 to 0.015%. Grain yield of winter wheat obtained in the experiment was ranging from 6.72 to 6.98 t ha ¹, and from 2.47 to 2.69 t ha ¹ for soybean grain, and both totaled from 9.2 to 9.7 t ha^-1 of grain yield per year.