Evaluation of wind erosion protective efficiency No-till technology in southern Ukraine steppe conditions

Abstract

The aim of the research was to the efficiency wind erosion control of farming system «no-till» (NT) for conditions of South Steppe of Ukraine. The research was conducted at heavy load southern chornozem in the crop rotation «pea – winter (spring) wheat – sorghum – mustard». In field experiment two options of processing of the soil (traditional and minimum) and NT were studied. Options aggregate of surface soil (0–5 cm), the weight of crop residues and projective covering the soil surface were determined. Research field was equipped by meteorological station and field’s wind erosion dust-meter. The efficiency wind erosion control by NT was evaluated in three directions: the presence of dangerous wind erosion period (February–April) a certain amount of plant residues, that protect of soil surface from extreme winds (1); presence during this period of high values of «random» surface roughness of the soil, which reduces the strength of the wind in ground layer of air (2) and values of soil wind erodibility index (3). Evaluation promises more effective in terms of opening up the soil surface crop residues reveals that NT fully meets the criterion of preserving (erosion control) technology – projective cover ground in a dangerous deflationary period is an average of three years of research on the crops of spring wheat – 37.9 % for sorghum crops – 71.1 % and on crops of mustard – 60.2 %. An important indicator of the erosion control efficiency of soil tillage is percentage of vertically oriented surface plant residues. Unbroken soil surface tillage after harvesting will have the maximum amount of such residues. Analysis of these studies show that when used NT observed maximum value of this parameter – 35–55 %, more than that in other tillage. So the version with traditional soil tillage this parameter does not exceed 5 %, and versions with minimal system soil tillage – 30 %. Estimation of effectiveness of soil protection NT via a «random» surface roughness also shows a high ability wind erosion control this technology. At the same time, it should be stated that the presence of high «random» roughness autumn plowing deep plowed fields, despite the fact that the surface of the soil in the case of poorly protected plant residues. The main index of soil wind erodibility is the fraction greater than 1 mm, the so-called «lumpiness». It is known, lumpiness indicator correlate with various other soil wind erodibility indicators, in particular, the mechanical strength of soil aggregates, containing wind erosion fraction by (<0.25 mm) and wind erodibility indicators there were obtained in portable wind tunnel. Intensive plowing of the soil leads to formation of a surface of the soil with high resistance by the strong winds in the fall (lumpiness – 70–90 %). It is connected with specific mechanisms of formation of soil structure. Plowing of solonetzic chernozems, especially after dry summer and an early autumn, leads to formation of soil structure units of the larger sizes. But during the winter of lumpiness by all options of researches gradually decreases, what is explained, first of all, by action on soil units of the procedures «melting» – «freezing» that, in turn, is function from the number of transitions of temperature of the soil through 0 °C. There is a destruction of soil aggregates and dispersion of the soil, in the conditions of an unstable temperature schedule in the winter, that is a consequence of warming of climate when in the afternoon of air temperature and the soil positive, and at night the soil freezes. At the same time, when the surface of the soil during the winter and at the beginning of spring is unploughed the soil condition, as it is observed on options with NT, the number of procedures of transition through 0 °C soil temperatures sharply decreases, so a destruction of aggregates goes not so intensively on the soil surfaces. But, according to our research, in the spring, lumpiness in variants of the NT is not diminished, was 50–70 %, the lower limit soil wind erodibility for chernozem. This phenomenon is bound to higher humidity of the soil which promotes coagulation of soil particles and existence of a large number of plant residues as source of the biological substances with capacity for bonding. These factors strengthen process of formation of aggregates, large by the size, what leads to increase soil lumpiness. Direct observations of NT wind erosion control efficiency during dust storms on 26^th and 27^th of January, 2014 showed that soil loss in NT was 3.5 times less them on a variant of traditional tillage and 2.9 times less them on a variant of minimum tillage.