The research was carried out on the territory of the Russian Federation in the forest-steppe region of the south Western Siberia (Omsk state), in the long-term (43 years) stationary experiment. Sprinkling was used for irrigation in the experiment. The number of different physiological groups of microorganisms, the cellulolytic activity of the soil, and nitrification capacity were determined under the sowing of an eight-field grain-grass crop rotation (perennial grasses (Bunias orientalis L. + Bromopsis inermis L. + Galega orientalis Lam. 6–8 years old), spring barley Hordeum vulgare Leyss.—variety Sasha). Immobilization processes predominated in the soil under the sowed crops, it contributes to the preservation of soil organic matter (mineralization coefficient SAA/MPA < 1). The highest transformation ratio of soil organic matter, i.e. increased conversion of plant residues into organic matter, was noted with applying nitrogen-phosphorus fertilizers (N60P60) under the barley. The combination of irrigation factors and the use of mineral fertilizers (N30-60P60) were contributed to the growth of the microorganisms’ population, the amplification of decomposition of cellulose, and improvement of nitrification capacity in the soil. The perennial irrigation of the meadow-chernozem soil and the application of intensive technology of cultivation of crops in crop rotation stimulated the growth of the microorganisms’ population and didn’t detriment the ecological state of the soil.

In stationary field experiments in the forest-steppe of Western Siberia, it was shown that long-term agricultural use of soil without the use of fertilizers caused a decrease in the soil content of heavy metals related to plant micronutrients — Cu, Zn, Co; the level of Pb, Cr, Sr has changed slightly. It was established that the long-term application of high, agronomically justified doses of mineral fertilizers, accompanied by a significant increase in the yield of cultivated crops, did not lead to an increase in the content of HM in the soil, compared with not fertilized areas. It was revealed that the unbalanced use of fertilizers, not ensured by the growth of crop productivity, contributed to the accumulation of HM in the soil. The necessity of monitoring the agro-ecological state of soils of agrocenoses in order to identify both excessive accumulation of heavy metals and micronutrient deficiency is substantiated.

In the conditions of dry-land farming, the leading factor of productivity, which is minimal, is moisture. Soil moisture directly influences the growth of plants by means of aeration, transfer of nutrient substances, absorption and transformation. The main crop acreage of the spike cereals in the south-east of Kazakhstan is located in dry farming lands that are characterized as dry and semidry, which means the region has a water deficit. The lack of natural moisture reserves, especially in dry years, as a rule, is one of the main reasons for the reduction in yields of winter wheat, which is the leading crop of non irrigated farming. The objective of this research is to determine the impact of the absorbing agent" Aquasorb" on the moisture reserve of soil and the yield of winter wheat. The research was performed in the field stationary land lot of the Kazakh Research Institute of Agriculture and Crop Production in the conditions of the semi provided dry farming land in the south-east of Kazakhstan. The field test was performed by means of applying the famous water-retaining absorbing agent "Aquasorb" before seeding winter wheat. The following application rates of the absorbing agent were used in the test: 0,20,40 kg/ha and their combination with the nitrogen top dressing in the dose N 45 . The results of the research revealed that the absorbing agent applied in the soil improved significantly the provision of winter wheat plants with the available moisture during the vegetation period and also made it possible to efficiently use the moisture for the formation of high yield.

No abstract

Unsustainable irrigation of chernozems can lead to secondary salinization and other negative consequences. The purpose of the research was to assess the fertility and hydrochemical composition of meadow-chernozem soil of the forest-steppe of Western Siberia under conditions of prolonged irrigation. The surveys were carried out in the fields of the agricultural production cooperative (APC) “Pushkinsky” and Federal State Unitary Enterprise (FSUE) “Omskoye”; cultivation technology – adaptive system of irrigated agriculture. The studies were conducted in 2015–2020 on the Pushkin irrigation system. The object of the research – irrigated meadow-chernozem heavy loamy soil. The methods of route field research and laboratory analyzes were used. The results obtained were compared with the baseline values (1978). With long-term irrigation and intensive agricultural use, the fertility indicators of meadow-chernozem soil did not significantly deteriorate. The arable horizons have a neutral and close to neutral reaction (pH 5.8–6.2), average humus content (5.9–7.2%). The supply of nitrate nitrogen, as a rule, remained at a low and medium level (6.0–14.7 mg/kg) due to the high removal by vegetative crops and the absence of fallow fields in the structure of irrigated arable land. Long-term systematic application of phosphorus-containing fertilizers and creation of a positive P balance led to the improvement of soil phosphate status (99–177 mg/kg). The content of exchangeable potassium remains high (144–353 mg/kg) and is stable over time, which is a feature of chernozems with a heavy particle size distribution. The content of mobile forms of lead, zinc and cadmium does not exceed approximate permissible concentrations in the soil. When analyzing the cation-anionic composition of the water extract of the soil profile of FSUE “Omskoe”, a weak salinity of the chloride type was revealed in the 0.6-1.4 m layer; of the sulfate-chloride type – in the 1.4-1.8 m layer. In the future, it may lead to secondary salinization and serve as a limiting factor for high yields. The absorbing complex of meadow-chernozem soil in the southern forest-steppe is highly saturated with bases. Sodium concentration is minimal; calcium and magnesium cations prevail. The groundwater samples are moderately fresh and of good quality. Among the anions, HCО3- prevails, among the cations – Mg2+ and Ca2+, which indicates the need to control the groundwater level to maintain a favorable ecological state of meadow-chernozem soil.