A.N. Khizhnyakov
Station of Agrochemical Service “Kurskaya”, Kursk, Engelsa st., 140A
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Summary. The article presents the work results and data analysis within the fifty year period on the dynamics of main fertility indices of soils in Kursk region. The change in the content of humus, mobile phosphorus, exchange potassium, and also the acidity of arable land in the arable horizon is clearly represented. The weighted average content of mobile phosphorus before the first cycle of agrochemical survey was 77 mg/kg of soil. Then during five cycles (from the second to the sixth ones) its content increased uniformly and reached the maximum 139 mg/kg of soil in 1995-1999. At the end of the first cycle (1969) the area of soils with very low content of mobile potassium was 0.6 %, with low one – 13.8 %, the soils with middle provision with the element predominated, 48.1 %. Then the value of this index increased during III-V cycles, and the maximal growth in IV cycle corresponded to the maximum of application of K2O with fertilizers. During 50 years the weighted average value of pH remained practically on the same level, 5.5. The area of acid soils to VII cycle also underwent insignificant changes. The reduction of weighted average content of organic matter in arable lands of Kursk region within the period of observation was not established.
Keywords: soil, fertility, humus, phosphorus, potassium, acidity.