INFLUENCE OF IRRIGATION ON CHANGE OF PROPERTIES OF SOIL AT GROWING OF LONG-TERM CULTURES IN THE CONDITIONS OF CRIMEA
The purpose of the research was studying of changes in the soil properties during different ways of watering the garden and the ways of their restoration and improvement. The research was carried out on experimental plots with different methods of irrigation. The watering was carried out with different water mineralization. When irrigating with mineralized water there takes place the process of salinization of soils due to the high concentration of sodium chloride in the irrigation water. Some conspicuous increase in the exchange of sodium was in the layer of 30... 70 cm in the irrigated areas and reached a low degree of salinization. The increase of the exchangeable sodium, but to a lesser extent was observed in the area where the sprinkler irrigation was carried out - 4.1... 5.4%, but it has not reached the lower limit of the low degree of salinization. Drip irrigation provides saving of irrigation water by 60... 70% - compared with irrigating two furrows with moistening of 75% of the area and by 70... 80% - compared with total moistening of the soil using traditional irrigation methods. After six years of irrigating with mineralized waters of sulfate-chloride, sodium-calcium compounds in the soil circuit of humidification the amount of salts increased from 0.9... 1.3 up to 1.5... 1.8 mEq/100g of soil depending on its depth. The amount of chlorine and sodium in the soil irrigated increases 3... 4 times, of calcium - 1.5 times. The chloride-sulfate type of salinization becomes the chloride one, the water suspension pH is reduced by 0.2... 0.5 units. The presence of gypsum in the irrigation water (5.8 mEq/L) mitigates adverse effects of harmful salts, reduces soil alkalinization. When changing the drip irrigation system for fresh water of the Dnieper there begins leaching of salts in the soil profile in the irrigation zone. Under a dropper down to the depth of 100 cm in the centre of the circuit of humidification the ash of desalinization was formed, the amount of salts there does not exceed 1.5, and down to the depth of 50 cm - 1 mEq /100g of soil. Irrigating with fresh and weakly mineralized waters on the background of 420 mm of precipitation per year does not lead to any raising of the groundwater level to critical values and to the accumulation of salts in the root volume of the soil. During drip irrigation with weakly mineralized waters on the southern black soil, in circuit of humidification the salts contained in the irrigation water accumulate. During local moistening with fresh water of the soil, earlie r become saline, the dilution of salts and shifting them to the periphery of the wetting zone with their further movement into the underlying horizons, resulting from infiltration. During desalination in the irrigation areas the process of salinization and alkalinization of the soil is expected to take place. Irrigating with different watering methods requires regular monitoring of the quality of irrigation water and processes taking place in the soil to prevent deterioration of properties and loss of soil fertility.