The work was carried out on Novotroitsk irrigation massif located in dry steppe zone of Al-tai Krai. The paper studies the impact of long-term irrigation (10-15 years) by water from Ob River fed via Kulunda main canal on the parameters of ameliorative condition of chestnut soils. The re-sults discover the direction of soil formation process, determines the degree of alteration of physical, chemical parameters of ameliorative condition depending on the irrigation duration and granulometric

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... ition of the soil. It was unveiled that the irrigation by hydrocarbonate water with the mineralization less than 0.3 g/l gives rise to the processes of solodization-leaching. Water converts humus into labile form that migrates into the soil body. Irrigation causes the pedologic and physical conditions to become less favorable for agricultural crops: it increases the number of microaggre-gates, waterproof aggregates larger than 0.25 mm, and raises their mechanical strength and water resistance, increases the soil density, reduces total porosity and water capacity, increases holard and chresard, reduces water permeability indicating the degradation processes in irrigated farm soils.