The influence of biologized crop rotations on organic matter and agrophysical soil layers in the arid steppe of the Southern Urals

Abstract

Relevance. The continuing deterioration of the state of agricultural lands and the natural environment in general requires a transition to conservation agriculture, of which biologized crop rotations are a part.The purpose of the research is to establish the influence of biologized crop rotations on the content of organic matter and agrophysical properties of the soil in the arid steppe of the Southern Urals.Methods. Field experiments and laboratory analyses were carried out according to generally accepted methods. The soil of the experimental field is ordinary medium loamy chernozem. The climate is arid. During the years of research, the hydrothermal coefficient was 0.27–0.65. In the experiment, we studied sevenfield biologized crop rotations with four grain fields, two alfalfa fields and pure steam (type I), with five grain fields and two alfalfa fields (type II). As a control, a six-field grain-pair crop rotation was taken. We created food backgrounds: without fertilizers, organic, mineral.Results. It was revealed that biologized crop rotations in the alfalfa link of the first and second years of use accumulate 7.8–9.1 t/ha of crop-root residues in the soil layer 0-40 cm, which is three to seven times more than the grain-pair crop rotation. The increased amount of PKO in biologized crop rotations has a loosening effect on the arable (0–30 cm) and sub-arable (30–40 cm) soil layers. The density of the arable layer is 1.10 g/cm³, the sub — arable layer is 1.05 g/cm³. Accordingly, the indicators of grain — pair crop rotation are 1.12 g/cm³ and 1.12 g/cm³, or 6% more. Biologized crop rotations contained higher moisture reserves in the soil. Spring reserves of productive moisture in the soil layer of 0–100 cm in biologized crop rotations — from 97 to 112 mm for fertilizer backgrounds, which is 8–22 mm more than in the grain-steam crop rotation. Thus, biologized crop rotations in the conditions of the arid steppe of the Southern Urals contribute to the optimization of agrophysical properties and improvement of the water regime of the soil.