State of humus and nutrition of leached chernozem under the effect of fertilisation and field of crop rotation

Abstract

Purpose. To study the state of humus and the content of mobile phosphorus and potassium in leached chernozem as affected by fertilisation system and the introduction of leguminous crops into the crop rotation. Меthods. Field experiment and analytical method. Results. The data on the content of humus, mobile phosphorus and potassium in the grain fields of crop rotation under the effect of different fertilisation systems are presented. It was established that the humus, mobile phosphorus and potassium content of soil increased significantly with the application of organo-mineral fertilisation system, while the factor of the field of crop rotation was insignificant. The mineral fertilisation system was inferior to the organo-mineral one in terms of its effect on the key fertility indicators of the soil. Conclusions. The application of mineral fertilisers in both grain fields of crop rotation promoted an increase in the humus content layer by 0.02−0.05% in the 0–30 cm compared to zero fertilisation (control). At the same time, application of N33.3Р13.3K20 and N50P20K30 in the field with pea provided a slightly higher increase in the humus content of soil compared to the control than in the field with buckwheat – 0.02% and 0.01%, respectively. The maximum content of humus in the soil − 4.06% in the 0–30 cm layer and 3.86% in the 30–40 cm layer − was achieved with the application of N50P20K30 + green manure + harvest residues ensuring 0.13% and 0.02%, respectively, increase to the control. Mobile phosphorus and potassium contents of soil were affected mainly by the factor fertilisation system. They were the highest in the field with pea under the organo-mineral fertilisation system (N50P20K30 + green manure + harvest residues): 138 mg/kg and 103 mg/kg in the 0–30 cm layer and 116 mg/kg and 67 mg/kg in the 30–40 cm layer, exceeding the control by 18 mg/kg, 25 mg/kg and 7 mg/kg, 5 mg/kg, respectively. The combined application of mineral and organic fertilisers significantly increased the amount of phosphorus and potassium income in the soil and ensured the highest content of their mobile forms. The application of mineral fertilisers was much less effective compared to organic-mineral in terms of the impact on the content of mobile phosphorus and potassium. The introduction of the leguminous crop to the grain field of crop rotation did not significantly affect soil fertility.