Influence of conditions of mineral nutrition, clean and occupied fallows on the fertility of the chestnut soil of the Eastern Ciscaucasia

Abstract

In conditions of a shortage of manure and high prices for mineral fertilizers, the preservation and improvement of soil fertility is an urgent problem of agriculture. The studies were carried out at the Prikumsk experimental selection station in two 6-field crop rotations from 1969 to 2019 The purpose of the research is to study, in a long­ term stationary experiment on various nutritional backgrounds, the effect of grain crop rotations with clean and busy fallow on the fertility of the chestnut soil in the arid zone of the Stavropol Territory. In the grain-and-row crop rotation with 16.6% of pure fallow, the decrease in the humus content in the control was 0.10%, the humus reserves were 2.6 t/ha, against the fertilized background — 0.09%, 2.3 t/ha, and with the occupied fallow on the contrary, it increased by 0.10%, 2.6 t/ha and 0.11%, 2.8 t/ha. The content of mobile phosphorus in the topsoil in the control with clean fallow increased by 1.7 mg/kg, stocks — by 4.3 kg/ha, with occupied fallow — 3.4 mg/kg and 8.7 kg/ha, and on the fertilized variant — 7.5 mg/kg, 19.1 kg/ha and 7.4 mg/kg and 18.9 kg/ha. The content and reserves of exchangeable potassium increased by 3 — 46 mg/kg and 8 — 115 kg/ha. In the crop rotation with clean fallow, they were 4.2-4.1 times lower on the control, and 13.7-13.0 times lower on the fertilized background, compared with the occupied fallow. The application of fertilizers contributed to a decrease in the potassium content in the crop rotation with clean fallow by 3.7 times, reserves by 3.5 times, and with busy fallow by only 12.2 and 10.6%. Sainfoin fallow significantly increased the content and reserves of potassium in the soil in the control and significantly reduced its consumption in the fertilized variant.