THE CONTENT AND THE FORMS OF MAGNESIUM COMPOUND IN LEACHED BLACK SOIL (CHERNOZEM) OF WESTERN CISCAUCASIA IN THE AGROGENESIS | Содержание и формы соединений магния в черноземе выщелоченном Западного Предкавказья в условиях агрогенеза

The article presents the results of the study on the magnesium mode of leached chernozem of Western Ciscaucasia at three rotation of grain-grass-tilled crop rotation. Magnesium in the soil is represented mainly by non-exchangeable form, the number of which is estimated at 90,18 and 91,29 % of gross reserves. Exchange forms of magnesium are 8,68 and 7,71 % respectively in arable and the subsurface layer. The share of water-soluble and organic forms account for less than 1 % - of 0.62 and 0.68 and 0.46 and 0.38% respectively. For three rotation 11-full rotation of gross stocks of magnesium in the soil in which crops were grown without fertilizers has decreased by 0.02 % (200 mg/kg), with fertilizers of 0.03 and 0.02 % (300 and 200 mg/kg). Intense magnesium has been leached from the topsoil. There was a change of the soil content of the forms of magnesium. In the rotation without fertilizer, the share of non-exchangeable magnesium in the General Fund item increased from baseline by 0.27 % in arable and 0.11% of the subsurface layer of soil that the absolute content decreased. The amount of water-soluble, exchangeable and organic magnesium of the soil decreased. Reducing the amount of water-soluble (0.05 and 0.06 %) and metabolic (0.18 and 0.02 %) of magnesium was due to its consumption of the plants. The proportion of magnesium organic part of the soil is reduced as a result of steadily declining yields, and, therefore, the amount of organic residues. In crop rotation, use of mineral fertilizers we have observed different behavior of magnesium compounds in the soil. The number of non-exchangeable magnesium decreased from baseline by 0.13 % in arable and 0,58 % of the subsurface layer of soil. The content of the exchange of magnesium increased respectively 0.43 and 0.41 %, water soluble - 0.13 and 0.10 %, and the organic part of the soil - 0.02 and 0.02 %