The aim of the research was to develop an assessment scale for a meliorative state of irrigated lands which reflects the type and intensity of soil fertility decline associated with the violation of their hydro chemical regime at irrigation development. The diagnostic scale was constructed on the basis of the balance-analytical (equilibrium salt balance model) and statistical methods that were tested in Engels, Privolzhskaya (Saratov Region) and on Volgodonsk irrigation systems (Volgograd Region). In addition, the laws of spatial variation of soil salinity, the depth and mineralization of groundwater obtained by the authors were considered. A new approach to the creation of assessment scale of a meliorative state of irrigated lands based on the depth and salinity of groundwater which are indicators of salinity and waterlogging of soils is argumented. Classification scale units correspond to a certain type and intensity of the negative process, determining the value of the decreasing coefficient to soil fertility, which is a prerequisite for the inclusion of monitoring data into the system of agroecological and economic assessment of land resources. For lands that are at the satisfactory state now according to the depth of groundwater, there are no grounds for applying decreasing coefficients for reducing soil fertility from the sights of salinization and waterlogging, whereas on lands classified as unsatisfactory this coefficient can vary from 1.0 to 0.12 depending on ratios of depth and mineralization of groundwater.
Key words: monitoring, irrigated lands, groundwater depth, mineralization, salinity, waterlogging, diagnostic scale, variation, fertility.
