FERTILITY OF LEACHED DEGRADED CHERNOZEM AND WINTER WHEAT PRODUCTIVITY IN CROP ROTATION AT DIFFERENT TILLERING PRACTICES AND FERTILIZATION SCHEMES
Intensive land reclamation during the last century and in the beginning of 21 <sup>st</sup> century lead to significant changes in the base indices of soil fertility. Humus and nitrogen contents reduced by 30-35%, soil was decalcified, its acidity grew and the buffering decreased. Thus, in the crop rotation with perennial grasses, humus content in 0-8 cm soil layer reduced in 80 years (1928-2008) from 4,98 to 3,04 % or by 39 %, and in the 40-45 layer - from 3,92 down to 3,27 % or by 30,1 %, nitrogen content reduced by 35,9 and 22% respectively. Absorbed СаО content reduced by 0,12 and 0,11% respectively, that caused water pH reduction from 6,9-7,1 to 6,1-6,4. It has been observed that while humus content in soil when ploughed at 25-27 cm depth remained at the initial level of 3,3%, when ploughed at different depths (chisel ploughing at 38-40 cm once in three years before row crops + surface tillering at 8-10 before cereal crops) and at subsoil tillage at 14-16 cm a little growth was observed from 3,26 to 3,32 and 3,28 respectively. Ameliorant application (defecate) significantly increased humus content at different depth tillering to 3,37 and at subsoil tillering - to 3,33%. The biggest humus reproduction was achieved at fertilization and ameliorant application - up to 3,-3,51% at minimal NPK ( <sub>85</sub>) and up to 3,61-3,65% at high NPK( <sub>181</sub>) application, texture density significantly decreased from 1,42 to 1,31-1,37 g/sm <sup>3</sup>, soil health aggregates share improved from 59-61 to 69-77 %. Calcium application significantly reduced hydrolytic acidity from 5,5-6,2 down to 3,8-4,7 mg equ./100g of soil. It has been determined that out of all studied practices the most effective practice for leached chernozem is the traditional technology (ploughing at 25-27 cm before cropping + subsoil tillering at 8-10 см before cereals) and decompressing (chisel ploughing before row crops at 38-40 cm once in three years + subsoil tillering at 8-10 cm before cereals).