ENVIRONMENTAL EFFICIENCY OF PERENNIAL LEGUMES AS PRECURSORS OF WINTER WHEAT GROWN IN THE CONDITIONS OF AGRICULTURAL LAND POLLUTION WITH HEAVY METALS

Abstract

The aim of the research was to study the effect of the inclusion of different types of perennial leguminous plants as winter wheat precursors in the crop rotation on the rate of accumulation of heavy metals in the soil compared to traditional winter wheat predecessors. The objectives of the research are to develop measures to reduce the accumulation of heavy metals in agricultural soils under conditions of modern crop rotation, limited by the number of crops grown and winter wheat. The accumulations of heavy metals in soils were calculated during the cultivation of the main crops of crop rotation with intensive fertilizer. The concentration of heavy metals in the soil was determined before and after the cultivation of legume precursors. Field studies were carried out during 2013-2017. On gray podzolized medium loamy soils of the Agronomichesky Research Institute of Vinnytsia National Agrarian University. We calculated the volumes of heavy metals with optimal rates of mineral fertilizer application for the most common types of crops grown in crop rotation. Four types of perennial grasses were sown: sowing alfalfa, meadow clover, horned lamb, sainfoin and eastern goatskin. After their four years of use, winter wheat was sown. The control was the predecessors in the following sequence: winter wheat - sunflower - winter wheat - corn. Laboratory studies of the content of mobile forms of heavy metals in soil were carried out in the Vinnytsia branch of the State Center for the Protection of Soil Fertility. Analysis of soil contamination with heavy metals during fertilization of major cereals showed that the amount of mineral fertilizers is from 257 kg/ha to 571 kg/ha for ammonium nitrate, from 175 to 225 kg/ha for double superphosphate and from 58 to 75 kg/ha on potassium chloride. According to the volume of mineral fertilizers used in the cultivation of winter wheat, 1944 mg / ha of lead and 339 mg / ha of cadmium enter the soil. Of these, with ammonium nitrate - 51.4% and 7.4%, respectively, with double superphosphate - 39.6% and 41.3% and with potassium chloride - 9.0% and 51.3%. When growing corn per 1 ha with mineral fertilizers, 2357 mg of lead and 434 mg of cadmium are applied, of which with ammonium nitrate - 48.4% and 6.7%, respectively, with double superphosphate - 42% and 41% and with potassium chloride. - 9.6% and 51.8%. Cultivation of spring barley leads to the receipt of mineral fertilizers to soils 1458 mg/ha of lead and 327 mg/ha of cadmium, of which with ammonium nitrate - respectively 35.2% and 4.0%, with double superphosphate - 52.8% and 42.8% and with potassium chloride - 12.0% and 53.2%. Mineral fertilization of winter rape leads to the entry into the soil per 1 ha of 2223 mg of lead and 390 mg of cadmium, of which with ammonium nitrate - respectively 51.4% and 7.4%, with double superphosphate - 39.6% and 41% and with potassium chloride - 9.0% and 51.5%. With mineral fertilizers for growing sunflower in the soil per 1 ha gets 2073 mg of lead and 427 mg of cadmium, of which with ammonium nitrate - respectively 41.4% and 5.2%, double superphosphate - 47.8% and 42.2 % and potassium chloride - 10.8% and 52.6%. The positive effect of growing leguminous perennial herbs on the decrease in the concentration of heavy metals in the soil and grain of winter wheat has been established. Under the conditions of intensive farming by Vinnitskaya, lead and cadmium fall into the soil for the use of mineral fertilizers in accordance with 1944 mg/ha and 339 mg/ha for growing winter wheat, 2357 mg/ha and 434 mg/ha for growing corn, 1458 mg/ha and 327 mg/ha when growing spring barley, 2223 mg/ha and 390 mg/ha when growing sunflower. The four-year cultivation of perennial leguminous grasses under intensive farming reduced the concentration of lead in the soil from 1.33 to 3.2 times and cadmium from 37 to 54 times compared with cereal crops, which contributed to improving the quality of winter wheat grain by reducing the concentration of lead from 1 7 to 2.4 times and cadmium from 1.4 times to 2.1 times. Key words: legumes, precursors, winter wheat, heavy metals, pollution.