LONG-TERM DYNAMICS OF HUMUS CONTENT UNDER DIFFERENT TECHNOLOGIES OF SOIL TILLAGE

The continuous agronomic experiment revealed long-term dynamics of the total humus content and presented a forecast of the change in humus content in typical low humus chernozem under different technologies of tillage till 2050. Aim. To determine the rates of humus accumulation dynamics and mineralization of total humus and to develop the forecast of the change in its content within a continuous agronomic experiment under long-standing application of different technologies of soil tillage to typical low humus chernozem of the Left-Bank Forest-Steppe of Ukraine. Methods. Field, laboratory-analytical, mathematical and statistical. Results. The application of different technologies of tillage to typical low humus chernozem for 42 years resulted only in the delay in dehumification processes and some stabilization of humus mineralization, but it did not promote its preservation and extended restoration to the initial level as of the start of the experiment. The increase in the total humus content for simple and extended restoration of humus in the centennial cycle equaled 20-25 t and 30-33 t per 1 ha respectively. To ensure the increase in content and reserves of humus for 42 years, it is necessary to introduce 10-12 t of humus per 1 ha for simple restoration of total humus content and 14-15 t per 1 ha - for extended restoration annually. Conclusions. Simple restoration of humus in typical chernozem may be stated after achieving its actual (2017) content of at least 90 % from the content as of the beginning of the centennial cycle (92 years), which ensures maximal approximation to the non-decreasing cycle of humus dynamics trends in the centennial cycle. If the humus content is ensured in the actual measurement for the level, exceeding 90 % from the initial content, and dynamics trends are growing, one may state the success of achieving the state of extended restoration of humus. The obtained state of simple and extended accumulation of humus is ensured by the positivity of the trends of humus increase during the continuous experiment (42 years) with simultaneous decrease in dehumification process in the centennial cycle (92 years) which is impossible to neutralize completely.