ASSESSMENT OF AGRICULTURAL PRODUCTIVITY OF SOILS IRRIGATED FOR A LONG TIME

Abstract

Purpose: to identify correction factors for accounting negative properties and to evaluate the agricultural productivity of long-term irrigated soils under various soil-reclamation conditions. Materials and methods. The object of research is the various types of soils developed during long-term regular irrigation. The analysis of soil samples was carried out according to generally accepted methods. The agricultural productivity assessment was carried out on the basis of the soil-ecological index, on the zonal soil bonitet, adjusted for soil properties and on the point of actual yield. Results. Correction points have been established to account the indicators of irrigation and groundwater in calculating the agricultural productivity of soils according to the soil-ecological index SEI. They range from 0 to 12 points. Correction factors for account the negative properties of long-term irrigated soils vary from 1 (soil properties during irrigation remain) to 0.7–0.6 units (indicate a strong change in soil properties). When calculating the agricultural productivity of soils according to the actual crop yield score, it was determined that soils with less than 30 points are assessed as ineffective for use in irrigated agriculture. It has been found that the agricultural productivity of soils irrigated for a long time with weakly saline waters (a decrease of 40–49 %), as well as the soils with natural adverse properties – southern chernozem and brown semi-desert soils is lost to the greatest extent. The smallest decrease is observed on dark chestnut soils (groundwater deeper than 3 m, fresh irrigation water and high farming standards). The agricultural productivity of soils decrease is observed when water of class II and III is used for irrigation, as well as in areas with close occurrence of alkali groundwater – from 5 to 17 %. Conclusions. When assessing the agricultural productivity of soils under various soil-reclamation conditions, preference should be given to calculations based on the actual yield points and adjusted for soil properties.

Keywords

• long-term irrigation
• soil properties
• integrated assessment
• agricultural productivity of soils
• soil bonitet
• productivity