The objective of the research was the study of the impact of phosphogypsum and
phosphogypsum-containig amendments on the properties of ordinary chernozem degraded
due to irrigation with mineralized water (1.7-2.0 g/dm3) as well as on the crop yield. It was established the decreasing of soil sodicity by 50 % upon applying the total calculated dose of phosphogypsum (10 t/ha), the increasing of calcium content in soil exchangeable complex up to optimal parameters (85 %), the achieving of good water-stability of soil. Applying the total calculated dose of gypsum (12 t/ha) in the same conditions ensured the decreasing of soil sodicity by 30 % and the increasing of calcium content in soil exchangeable complex up to 81 %. It was noted the significant improvement of physical soil properties under the impact of phosphogypsum: porosity increased from 47 (satisfactory) to 56 % (excellent), the percentage of water-stable aggregates increased from 30 to 50 % (water-stability changed from satisfactory to good), the soil density decreased from 1.46 to 1.16 t/m³ (the soil changed the category from strongly hardened to hardened). The phosphogypsum applying increased crop yields on an average by 46 % including winter wheat – by 54 %, fodder beet – by 31 %, soybean – 52 %. High efficiency of applying the fertilizing-ameliorative composts with phosphogypsum was proved. The potato yield increased by 10.6-11.8 t/ha next year after phosphogypsum applying and over a period of six years the average yield increasing was 36-44 %. For comparison composts containing glauconite showed the ameliorative effect only in the third year. The average supplementary production value was from 68.4 to 72.4 thousand rubles per hectare, economic effect – 65.3-70.0 thousand rubles per hectare over the six years after applying of phosphogypsum-containig amendment.
