The aim of the research was to study the influence of grain sorghum on soil fertility. In irrigated conditions of Rostov region the experiments were carried out on selecting cultivars and hybrids of grain sorghum to determine the ratio of grain and stubble remains in the structure of above-ground mass of plants. The experimental plots were conducted by the methodology of B. A. Dospekhov; the content of macro- and microelements in the crop yield was determined by spectrophotometric method. There were eight cultivars under study: Khazine 28 (control), Zernogradskoye 53, Orlovskoye, Luchistoye, Aist, SP 112, SP 214, and SP 270. It was established that the greatest yield of the whole biomass was obtained for cultivars SP 270 and SP 214, the yield was 103.5 and 99.9 t/ha respectively, including grain – 14.9 and 14.8 t/ha, root remains – 10.8 and 10.4 t/ha, mass of leaves and stems – 77.76 and 74.70 t/ha. The greatest quantity of microelements was in biomass obtained at growing of the same cultivars; the total content of microelements in stubble remains was 5572.5 and 5378.6 g/ha respectively, including iron – 4347.0 and 4195.8 g/ha, copper – 165.6 and 159.8 g/ha, zinc – 434.7 and 419.6 g/ha, manganese – 610.7 and 589.4 g/ha, cobalt – 13.5 and 13.0 g/ha, and iodine – 1.0 and 1.0 g/ha. It is established that humus reserves in soil of experimental plot were 486.3 t/ha. Incorporating of grain sorghum stubble remains by the mass of 31.29–52.60 t/ha of dry matter into the soil as an organic fertilizer provides the expected completion of humus from 4.7 t/ha for the cultivar Orlovskoye to 7.9 t/ha for the cultivar SP 270.
Keywords: grain sorghum, crop yield, stubble remains, irrigation, organic matter, microelements.
