Fertility of slightly saline chernozem under the effect of long-term fertilization system and tillage method in short crop rotation

Abstract

Purpose. To give a substantiation of the effect of the long-term fertilization system and methods of tillage on the fertility of slightly-saline chernozem in short crop rotation and to define optimal physicochemical and agrochemical parameters of the soil.Methods. Field, laboratory, and statistical.Results. On the slightly-saline chernozem, with the application of 6.25 t/ha of manure + N33.7P33.7K33.7, humus content in the arable soil layer increased by 0.20 % and reached 4.57 %. In the treatment with combined tillage, the values were 0.09 and 4.46 %, respectively. Under the application of 6.25 t/ha of manure + N33.7P33.7K33.7, the content of alkaline hydrolysed nitrogen in the arable soil layer increased by 16.0 mg/kg with ploughing and by 8.0 mg/kg with combined tillage compared to the beginning of the rotation, when the values were 135 and 135 mg/kg, respectively. Ploughing harvest residues into the soil + N33.7P33.7K33.7 resulted in the increasing mineral nitrogen content in the soil. Specifically, with ploughing, the nitrogen content increased by 5.7 mg/kg; in the under-ploughed soil layer by 6.7 mg/kg compared to the beginning of the crop rotation with the values of 23.9 and 20.0 mg/kg, respectively. In the treatment with 6.25 t/ha of manure + N33.7P33.7K33.7, 42.0 mg/kg of mobile phosphorus was determined in the ploughed soil layer with ploughing and 43.0 mg/kg with combined tillage. The content of exchange potassium on the background of the 6.25 t/ha of manure+ N33.7P33.7K33.7with both ploughing and combined tillage stabilized at 125 and 115 mg/kg, respectively.Conclusions. Application of 6.25 t/ha of manure + N33.7P33.7K33.7 ensured an increase in the content of humus in the arable soil layer with ploughing and combined tillage from 0.20 to 0.09 % and its stabilisation at 4.57 and 4.46 %, respectively. When applying only harvest residues on the background of mineral fertilizers, a positive balance of humus was observed, 4.55 and 4.51 %, respectively. With the application of6.25 t/ha of manure+ N33.7P33.7K33.7, the content of mineral nitrogen in the arable soil layer increased compared to the beginning of crop rotation by 7.5 mg/kg of soil, with combined tillage by 8.3 mg/kg or 48.0 and 52.8 %, respectively. The content of mobile phosphorus with 6.25 t/ha of manure+ N33.7P33.7K33.7 and ploughing stabilized at 42.0 mg/kg, with combined tillage 43.0 mg/kg. The amount of exchange potassium made up 125.0 and 115 mg/kg, respectively.