The influence of irrigation on physicochemical properties of ordinary chernozyom of Northern Kazakhstan

The comparative assessment of change physi-cochemical properties of irrigated and not irrigated ordinary carbonate light clay chernozyoms is pre-sented. The monitoring of investigation transfor-mation of physicochemical properties of ordinary chernozyoms were conducted on arable grounds of Akmola region of Kazakhstan, which were present- ed in 2 stationary environmental areas on non- irrigated areas and irrigation. The analyses of soils were conducted in the following types and meth- ods: carbon dioxide carbonates by acidimetrically, humus on Tyurin in the modification Simakov, total nitrogen by Kyeldahl, gross phosphorus by Ginsburg, mobile forms of nitrogen by Tyurin and Konova, mobile phosphorus and potassium on Machigin, exchange sodium in the flame photome-ter, exchange calcium and magnesium by Shmuk in Tyurin's modification. The purpose of this work was to study the effect of long-term irrigation on physi-cochemical properties and fertility of ordinary chernozyom. The objectives of this research were the physicochemical properties of soils, character of the direction of change in soil fertility and the development of proposals for the prevention of the negative consequences of irrigation. It was shown that with prolonged irrigation by low-mineralized waters their alkalinization occurred and sodium percentage reached 5 %. In the absence of organic fertilizers introduction there was a decrease of hu-mus content and, conversely, at introduction of ma-nure together with mineral fertilizers soils fertility increased. The process of dehumification in the irrigated soils was higher than in non-irrigated chernozyoms, so from 2013 to 2015, the quantity of humus had decreased from 4. 87 to 4.34 %. Some increase in carbonates mobility, which was con-firmed by chemical methods, was noted in the irri-gated chernozyoms. For 15 summer period of an irrigation from 2000 to 2015 the quantity of CaCO3 in a layer of 0-10 cm decreased from 2.72 to 1.28 %, in a layer of 10-20 cm from 3.13 to 2.35 %, in a layer of 20-30 cm from 5.03 to 2.70 %, in a layer of 30-50 cm from 6.84 to 5.47 %, and in the underly-ing soil profile, changes in the content of calcium carbonates were not observed. In the arable layer decreases the sum of absorbed bases due to calci-um leaching down by profileand made it to harvest crops, which for 15 years in the 0-30 cm layer de-creased by 3.11 mEq /100g of soil. Increased availability of mobile soil nutrients (nitrogen, phos-phorus, potassium) in the irrigated chernozyoms was due to the systematic application of organic and mineral fertilizers in quantities exceeding the crop needs nutrients.