POTASSIUM RESERVE IN SOILS OF THE VLADIMIR OPOLYA FROM A POSITION OF THE CONTENT OF MINERALS - BEARIERS OF NUTRIENT ELEMENTS FOR PLANTS

The aim of the study is estimation of potassium reserves of agrogrey heavy clay loam soil of Vladimir opolie on the basis of differentiated analysis of its contents in fractions less than 1, 1-5, 5-10 microns. The object of research is agrogrey heavy clay loam soils of a trench created on the loess loam. Minimum content of aluminum and iron as well as the greatest amount of silicon oxide is noted in the plough layer. The latter could be explained by involvement of eluvial part of natural soils. The content of elements oxides in oozy fraction significantly differs from that of the bulk soil. The amount of silicon oxide is sharply reduced whereas the way of its distribution on a profile is uniform (49.5-51.2 %). Significant increase in iron and aluminum oxides content (10.1-11.1 % and 18.2-19. 1 %, respectively) is noted. In comparison with the bulk soil the oozy fraction is enriched with gross magnesium. The amount of calcium oxide potassium oxide content in silt is only slightly greater than its quantity in the soil as a whole. The gross chemical composition of oozy fraction indicates that this fraction consists mainly of clay minerals characterized by high amounts of aluminum, iron, magnesium and potassium. The main components of fraction are irregular mixed-layered units, mica - smectites with the high contents of smectite packages dominate. Smectite phase and hydromicas comprise 85-90 % of the sum of silt components. The amount of kaolinite and chlorite fluctuates within 10-15 %. These minerals are sources of potassium, magnesium and determine soil anions behavior. Reserves of potassium in oozy fraction is the highest in comparison with fractions of a fine and medium dust as the main potassium carriers are minerals comprising more than 80 % of all minerals of fraction. Thus, the greatest amount of such nutrients as potassium, phosphorus, magnesium is fixed in fine fractions, in the oozy -phosphorus, and magnesium, in oozy and fine-dust fraction - potassium, magnesium. Periodic addition of part of illuvial horizon during plowing is necessary for compensation of natural nutrients stocks. The last prevents textural differentiation of a profile, fills up number of fine fractions along with elements of plant nutrition. obtained results serve as evidence of a direct connection between the minerals, their crystallochemistry, the dissociation degree and the availability of nutrient elements to plant communities. There are various approaches to assess the storage (reserve) of nutrient elements. Gorbunov (1969, 1978) offered the differentiated assessment of such reserves containing in minerals. Each element is concentrated in certain minerals. For example, potassium - in feldspar, mica, hydromica; magnesium - in biotite, chlorite, vermiculite, etc., phosphorus - in apatite, phosphates of potassium, calcium, etc., and also in the state absorbed by clay minerals. The total storage of elements is divided by N.I.Gorbunov into four categories: general, potential, near, direct.

Potassium reserve, agrogrey soil

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