Dynamics of soil fertility parameters in the Zaporizhzhya region and the ways of its restoration

Abstract

During 2000–2018, the results of the application of organic and mineral fertilizers in dynamics and their effect on the content of humus and nutrients in the soils of the Zaporizhzhya region were reviewed. To control the state of soil fertility use the calculation of the balance of humus and nutrients. This makes it possible to determine the extent to which the application of nutrients with fertilizers covers their removal by crop yields. Negative tendencies have been identified, which have led to the deterioration of soil fertility in the Zaporizhia region. Measures are proposed to achieve a deficit-free balance of humus and nutrients. On average, in 2000–2018, the level of mineral fertilizer application in the Zaporizhia region remained low – 38 kg/ha (nitrogen – 28 kg, phosphorus – 7, potassium – 3 kg), and manure – only 0.2 t/ha. According to the results of agrochemical certification of agricultural lands, the dynamics of changes in the content of humus, easily hydrolyzed nitrogen, mobile compounds of phosphorus and potassium over the past 18 years has been determined. The average weighted content of humus in the soils in the VIII round was 3.44 %, IX – 3.52, X – 3.40, XI (2016–2018) – 3.57 %, which indicates the stability of this indicator. The weighted average nitrogen content, which is easily hydrolyzed during all rounds, has close values (83.6–90.3 mg/kg) and corresponds to a low level of its supply. The content of mobile phosphorus compounds during the VIII – IX rounds was quite stable (97.1–101.6 mg/kg), and in the X–XI rounds there was even an increase to 123.3–123.4 mg/kg. The phosphorus regime of soils is stable and corresponds to the increased level of security, except for the ninth round (average). Potassium regime of the soil for eighteen years also remains stable and refers to a high level of security (159.6–176.8 mg/kg). The balance of humus and nutrients in the soils of the region remains negative. There is a tendency of positive changes if we compare the results for the first (2003–2014) and second (2003–2018) periods. Thus, to achieve a positive balance of humus it is necessary to apply 2 t/ha of straw (+400 kg/ha), 20 kg/ha of nitrogen fertilizers and 6.4 t/ha of manure, and in 2003–2018 – respectively 2 t / ha straw (+400 kg/ha), 20 kg/ha of nitrogen, 5.8 t/ha of manure. Key words: soil, balance, dynamics, humus, fertility, organic and mineral fertilizers.