Effect of fertilizing systems on changing the agrochemical properties of black soil typical under using tilled crops rotation by-products as an organic fertilizer during the crop rotation

Abstract

In general, the average annual loss of humus was 1.96 t/ha, 1.14 t/ha and 0.24 t/ha, respectively, for zero, first and second fertilizer levels in crop rotation, while the increase for the third level made 0.44 t/ha. At the highest fertilizer rate, total nitrogen reserves in crop rotation increased by 0.89 t/ ha. The annual application of 12 tons of manure + N95P82K72 per hectare of arable land ensured a deficit-free balance of humus in crop rotations and a slight decrease of 2.3 % of ammonia nitrogen in the arable layer over five years, which did not exceed LSD0.05. With the highest fertilizer rate, the ammonia nitrogen content in the black soil typical for five years increased by 2.0 mg/kg in total in crop rotations. The fertilizer rate of 12 t/ha of manure + N95P82K72 stabilized the mineral nitrogen content in the soil and the dose 159 of 16 t/ha of manure + N112P100K86 significantly increased the level in the crop rotation. Increase of available phosphorus content and potassium exchange in soil at the application of 12 t/ha of manure + N95P82K72 was not significant and made 1.0 mg/kg. The highest fertilizer rate significantly increased the content of these nutrients in the typical black soil arable layer. Over five years, exchange acidity at zero, first, second and third fertilizer levels decreased by 0.11, 0.10, 0.16 and 0.22, respectively, with the total for crop rotation of LSD0.05 0.12. Soil hydrolytic acidity for crop rotation at zero and first fertilizer levels increased by 0.15, and at second and third fertilizer levels – by 0.20 and 0.28 mg – eq/100g, respectively. The degree of soil saturation with the bases decreased during the rotation period at fertilized and unfertilized plots, but significant decrease was observed only at application of 16 tons of manure + N112P100K86 per hectare of arable land. The content of calcium exchange cations in the soil only decreased significantly during the rotation period when the highest fertilizer rate was applied annually. No significant deviations were found in the content of magnesium exchange cations in the soil. The crop rotations at unfertilized plots, fertilized with 8 t/ha of manure + N76P64K57, 12 t/ha of manure + N95P82K72 and 16 t/ha of manure + N112P100K86 were 2.35, 3.61; 4.77 and 5.77 t/ha dry matter respectively, 3.21; 5.04; 6.64 and 8.00 t/ ha feed units, 0.296; 0.422; 0.560 and 0.691 t/ha digestible protein at LDS0.05, 0.38; 0.51 and 0.043 t/ha, respectively. Key words: fertilizers, crop rotation, soil, crop, agrochemical properties, rotation period, yield, productivity.