Results and prospects of optimization of agrochemical indicies of arable soils fertility in Belarus

Abstract

A critical overview of dynamics of agrochemical indices of arable soils fertility over 50-year period is presented. The low-yield sod-podzol and swampy soils of Belarus were relatively poor in available plant nutrients. As a result of the largescale water engineering, liming and the intensive use of fertilizers over the period of 1965–2020 the productivity of arable land increased from 1.5 to 4.6 tons per hectare in grain equivalent. The significant improvement of soil fertility status was also achieved. Data of soil fertility status are based on the large-scale soil test monitoring conducted by State Agrochemical Service every 4–5 years. The share of strongly and moderately acid soils with pH < 5.0, that are harmful for the main crops, decreased from 66.8 % in 1970 to 4.5% of total area of arable land in 2004. However, the share of acid arable soils increased up to 9.8% in 2020, due to insufficient volume of liming that will be increased in the forthcoming years. The average organic matter (O.M.) content had been strongly increased from 1.77 to 2.28 % during the period of 1970–2000, due to high share of perennial grasses in cropping structure and manure application up to 14–15 t/ha per year. About 1 million ha of drained soils with the high O.M. content was also involved to arable land. The average O.M. content in the last two decades had been in mobile equilibrium of 2.23–2.27 % with a tendency to decline in some districts. The average contents of mobile Phosphorous and Potassium in arable soils increased up to 2.4–3.2 times during the experimental period and they are in the optimal range for cultivated crops. Currently balanced fertilization is the most important, with differentiation of fertilizer rates that would be most suitable to crop requirements and soil tests on each field. Formation and maintenance of optimal soil fertility indices, especially pH and mobile Р₂О₅ and К₂О contents, are strictly controlled as protective measures on the land contaminated with radionuclides ¹³⁷Cs and ⁹⁰Sr after Chernobyl accident. Measures to improve the efficiency of capital investment at fertility reproduction and use of arable soils are discussed currently.