The purpose of the work is to study the effect of the methods and rates of phosphogypsum application on the physical properties of integrated soil cover. The study has been conducted in the Salsk district of Rostov region. The object of research is black southern chernozems (zonal soils) and alkali soils that make up the integrated soil cover with more than 35 % alkali. According to the trial arrangement the phosphogypsum effect on the alkali soils and zonal soils properties against the background of deep tillage when applying accepted (overall application) and proposed (selective application) practice on the soil complex has been studied. The studies revealed that the method of phosphogypsum application – overall or selective – had no impact on the physical indicators but green manuring, deep tillage and application of phosphogypsum improved physical properties of the complex soil cover. Optimum indicators were obtained on solonetz during green manuring, deep tillage and chemical reclamation by rate of phosphogypsum 10 t/ha. In this variant in the third year of the complex reclamation the bulk density of soil in the layer 0–40 cm was equal to 1.27 tons per cubic meter (before reclamation – 1.50 tones per cubic meter), porosity – 52 % (44 %), structural state of the wet sieving – 58 % (39 %), water resistance – 58 % (39 %). This physical condition was still preserved in the fifth year of reclamation impact. For chernozem the best rate of phosphogypsum was 5 t/ha (the absolute designated rate). Its duplication hasn’t contributed to the significant improvement of the soil physical properties. It’s been concluded that it’s appropriate to give preference to a selective method of reclamation, i. e. to reclame the whole site with phosphogypsum rate calculated for the chernozem, of 5 t/ha, and then apply the remaining rate of ameliorant (5 t/ha) on alkali soils.
Keywords: comprehensive cover, chemical reclamation, phosphogypsum, green manuring, deep tillage, soil bulk density, water resistance, porosity.
