CULTIVATION TECHNOLOGY SUDAN GRASS HAY ON BROWN SEMIDESERT SOILS KALMYKIA
The article presents the results of experimental studies on the development of improved technology of cultivation of Sudan grass hay under irrigation in the arid conditions of Kalmykia, based on the selection of high-yielding varieties, the regulation of nutrient and water regimes to ensure rational use of irrigation water on the formation of planned productivity of up to 15... 18 m / ha of hay. To realize the potential productivity of Sudan grass varieties under arid conditions on brown semidesert soils optimal structure formed when sowing seed rate 4.5... 5 million units / ha. Highest productivity of hay is formed at the middle-grades Kamyshinskaya -51, Mnogootrastayuschaya and seeding rate at 4.5 million units./ha - 10,67... 13,47 t/ha in mid-early variety hay yields bystranka 13,34 t/ha achieved with seeding rate of 5,0 million units./ha. It has been established that the application of fertilizers at a dose N <sub>120</sub>P <sub>100</sub> in conjunction with irrigation provide an increase in the average yield of hay 5,73... 8,54 m/ha or 72,8... 97,4%, compared to the control - no fertilizer. The results showed that most effectively spent on crop formation water in areas where mineral fertilizers were applied dose N <sub>120</sub>P <sub>100</sub> kg /ha ai and maintain soil moisture at 75% of the HB 80 - 341 m <sup>3</sup>/t on average in 2007... 2010. Revealed that during wet years for moisture should be maintained predpolivnoy threshold soil moisture at 65... 70% of the HB with fertilizer doses N <sub>60</sub>P <sub>40</sub> and N <sub>80</sub>P <sub>60</sub> kg /ha ai, profitability index cost is 1,78... 2,07. In dry and very dry years economically advantageous to keep the pre-irrigation moisture soil at 75... 80% of the HB with fertilization in a dose N <sub>120</sub>P <sub>100</sub> kg/ ha ai, net income is 18,62 rubles/ha, with an index of the cost of return - 2,16. The practical significance of the results is that the implementation of the results will increase the area sown with Sudan grass on reclaimed lands, ensuring efficient use of irrigation water and receive up to 15 tons k.ed. /ha.