Influence of livestock complexes wastewater irrigation on the salt mode of soils
Increasing crop yields involves the introduction of not only mineral, but also organic fertilizers into the soil. The disposal of manure of large livestock complexes in adjacent fields in combination with irrigation is of particular relevance at present. This allows, on the one hand, to reduce the load on treatment facilities, and, on the other hand, to improve the soil fertility of adjacent farmland. The article presents the results of monitoring the hydrogeological and reclamation state of the lands in the state farm «Roschinsky» in the Sterlitamak district of the Republic of Bashkortostan irrigated with wastewater from the livestock complex. It is revealed that for the periods from 1987 to 1997 irrigation with wastewater caused an increase in the mineralization of soil solutions from 0,007-0,096 to 0,34-0,45 %. The accumulation of sodium, magnesium, calcium, sulfate and chlorine ions in soils took place. The capacity of the soil-absorbed complex decreased from salinity of the groundwater underwent significant changes. The content of sulfates (from 20-40 to 150-350 mg/l), chlorine (from 10-20 to 100-200 mg/l), sodium (from 10-50 to 70-100 mg/l) increased. The mineralization increased from 0,6-0,7 to 1,4-2,7 g/l. The deterioration of soil properties was also observed in the subsequent observation period from 2006 to 2010. Exceeding the boundary value of the dry residue for non-saline soil (0,25 %) in the meter soil layer was noted in 2010 at 9 out of 10 observation points, while in 2006 - only at 1 observation point. The total amount of water-soluble salts in a meter layer of soil from 2006 to 2010 increased by 14,2 t/ha, including toxic salts by 9,57 t/ha. To prevent the further development of salinization processes, the disposal of livestock stocks must be alternated with seasonal preventive leaching of the soil against a background of closed horizontal drainage, as well as increasing the area of the irrigated area and including salt-resistant crops in the rotation.