The effect of mineral fertilizers on the phosphate stock of leached chernozem and the productivity of grain crops

It was found that the content of readily available phosphorus in the soil of the small-scale experiment after 3 years of fertilizer application remained average in all variants, fertilizers compensated for its removal by grain crops. In the field experiment, the content of this form of phosphorus in the arable soil layer significantly increased only with row fertilization, with other methods of application it decreased to low. Fertilizers in both experiments, with all methods of application, not only compensated for the removal of mobile phosphorus by cereals, but also created a high and increased supply of plants with it. They increased the content of mineral phosphates and did not affect the ratio of their groups in the soil. The active fractions accounted for 22–25 %, Ca – P 3 phosphates accounted for 68–72 %, the proportion of Al – P and Fe – P phosphates was the lowest and practically unchanged, indicating the absence of rearrangement and fixation of phosphates into less accessible and inaccessible forms for plants. Phosphorus of fertilizers was absorbed not only by plants, but also by microorganisms. The most microbial phosphorus in a layer of 0-20 cm of leached chernozem in a small–scale experiment was found with local fertilization – 22 kg /ha, and in the chernozem of the field experiment – with row application – 31 kg / ha, which can be used by plants in the aftereffect. In the soil layer of 0–40 cm of the small– scale experiment, the reserves of microbial phosphorus, depending on the method of fertilization, increased in a row: row – scattered – local, and field: scattered – local – row. Only when applied to rows during sowing with seeds, fertilizers significantly increased the yield of spring wheat, the increase from them in small–scale and field experiments averaged 42 and 26 %, respectively. The highest yield of oats in conditions of sufficient moisture supply of the soil was obtained with scattered fertilization in action and with row–in aftereffect, the increase in yield was 12 and 20 %, respectively. The balance of readily available phosphorus in the chernozem of the field experiment is positive for all methods of fertilization, with its deficiency in the control – 26 kg /ha, and mobile – positive in all variants.