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A chromite occurrence called the Sabantuy paleoplacer was discovered in the Southern Pre-Ural region, at the east edge of the East-European Platform in the transitional zone to the Ural Foredeep. A ca. 1 m-thick chromite-bearing horizon is traced at a depth of 0.7–1.5 m from the earth’s surface for the area of ca. 15,000 m2. The chromspinel content in sandstones reaches 30–35%, maximum values of Cr2O3 are 16–17 wt.%. The grain size of detrital chromspinel ranges from 0.15 to 0.25 mm. Subangular octahedral crystals dominate; rounded grains and debris are rare. The composition of detrital chromspinel varies widely and is constrained by the substitution of Al3+ and Cr3+, Fe2+ and Mg2+ cations. Chemically, low-Al (Al2O3 = 12 wt.%) and high-Cr (Cr2O3 = 52–56 wt.%) chromspinel prevail. The compositional analysis using discrimination diagrams showed that most chromites correspond to mantle peridotites of subduction settings. Volcanic rocks could be an additional source for detrital chromites. It is confirmed by compositions of monomineralic, polymineralic and melt inclusions in chromspinels. The presented data indicates that ophiolite peridotites and related chromite ore associated with oceanic and island-arc volcanic rocks, widespread in the Ural orogen, could be the main sources of the detrital chromspinel of the Sabantuy paleoplacer.

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The variety of soil and climatic conditions, field topography, precipitation, soil type and vegetation cover of various zones of Russia indicates the need to choose the technology and complex of machines for cultivating crops in accordance with the conditions of the farming zone. At the same time, one of the main factors for obtaining high yields of high-quality grain is the method of cultivated crops sowing and the type of coulter used. Depending on the sown area of the farm, the sowing of various crops seeds is carried out by tractors of the 1,4-8 traction class, which requires the development of sowing machines with different capture widths, row spacing and depth of seed embedding in the soil. In this regard, there is a need to develop a design scheme and substantiate the parameters of the sowing machine and its nodes, made of the same type of modules with different working widths, made up into a sectional frame and equipped with a universal sowing section with replaceable anchor, disk, keel, T-shaped and spear coulters for sowing crops cultivated using various technologies. At the same time, the sowing machine should have a low metal consumption, minimal traction resistance and maximum productivity, meeting the agrotechnical requirements for various crops sowing.

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РАЗРАБОТКА РЕСУРСОСБЕРЕГАЮЩЕЙ ТЕХНОЛОГИИ И ОБОСНОВАНИЕ ПАРАМЕТРОВ КОМПЛЕКСА МАШИН ДЛЯ ВОЗДЕЛЫВАНИЯ СЕЛЬСКОХОЗЯЙСТВЕННЫХ КУЛЬТУР В ЗОНЕ УРАЛАКлючевые слова: почвенно-климатические условия; свойства почвы; сельскохозяйственные культуры; технология; обработка почвы; посев; комплекс машин; металлоемкость; тяговое сопротивление; производительность; урожайность.

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