Intra-soil milling for long-term efficient land use prospects
<p>Current land-use policy needs for innovative soil processing technologies. We carried out a long-term field experiment on the Kastanozem in following options: moldboard plowing to a depth of 22 cm; chiselling to a depth of 35 cm; three-tier PTN&#8211;40 plowing to a depth of 40&#8211;45 cm; PMS&#8211;70 intra-soil milling of the 20&#8211;45 cm layer. Moldboard, chisel and three-tier plowing does not improve soil aggregate system. 20&#8211;45 cm soil layer milling by PMS&#8211;70 provides the formation of the 1&#8211;3 mm aggregates. 30&#8211;40 years after PMS&#8211;70 processing, the soil profile structure remained fine aggregate. Soil organic matter and dissolved organic matter content, as well as the soil productivity, were higher after PMS&#8211;70. New intra-soil milling machine PMS&#8211;260 was developed. The moldboard plowing did not change the natural soil profile vertical morphological differentiation. The soil loosening effect was short-term after soil chiselling. After the three-tier PTN-40 plowing, a large part of humus horizon material strews down the soil profile between the chaotically spread large structural blocks of illuvial and transitional horizons. After PMS&#8211;70 processing, the content of 1&#8211;3 mm size aggregate particle fraction in the illuvial horizon was triple compared to the three-tier PTN&#8211;40 plowing. The soil desalination was intensive after PMS&#8211;70. The absorbed Na<sup>+</sup> content in solonetz was about 18&#8211;20% of soil cation exchange capacity (CEC) in the moldboard option. The same was after the chiselling. The CEC Na<sup>+</sup> content was of 14&#8211;16% after the PTN&#8211;40. The CEC Na<sup>+</sup> content was of 10&#8211;12% after the PMS&#8211;70. The SOM content in the 0&#173;&#8211;20 cm soil layer was 2.0%, in the 20-40 cm layer of 1.3%; the DOM content was 0.03% and 0.02% respectively in moldboard plowing option. The SOM and DOM content increased slightly in a period 3&#8211;4 years after chiselling. The SOM content was 2.2% in the 0&#173;&#8211;20 cm, and 1.4% in the 20&#8211;40 cm; the DOM content was 0.04% and 0.03% respectively after the PTN&#8211;40. The SOM content increased to 3.3% in the 0&#8211;20 cm soil layer, and to 2.1% in the 20&#8211;40 cm layer; the DOM content increase was 0.05% and 0.04% respectively after the PMS&#8211;70. In the moldboard option, the rhizosphere developed only in the upper soil layer of 0&#8211;20 cm. The rhizosphere spreads through the soil crevices after chilling. The conditions of rhizosphere development were better in the local comfort zones of the soil profile after three-tier PTN&#8211;40 plowing. The rhizosphere developed well and uniformly both in the upper 0&#8211;20 cm and in the 20-45 cm layer after intra-soil milling by PMS&#8211;70. Improved plant growing conditions provide higher plant resistivity to pathogens. &#160;The technology life cycle profitability: moldboard 21.5%, chiseling 6.9%, three-tier 15.6%, intra-soil milling 45.6%. The new design of intra-soil milling machine provides five times less traction resistance; 80% increased reliability, halving energy costs. Intra-soil milling provides long-term land-use prospects.</p><p>The research was supported by the RFBR, project no. 18-29-25071, and by the President of the Russian Federation, no. MK-2244.2020.5.</p>