Features of formation and transformation of fallows and methods for their optimisation

Abstract

Aim . The objective of this research was to establish the reasons for productivity reduction and changes in the species and quantitative composition of phytocenoses of multiple‐aged fallows and to develop methods for their use optimisation. Material and Methods . The research was conducted as a stationary field experiment. The fallow was formed since 2004 on the site of a field crop rotation. Fallow soil was moderately and heavily washed black earth. Results . It was established that the availability of soil with plant nutrients in all experimental variants did not differ much during the entire period of research. The bases for changes in the fallow productivity were not chemical but rather physical soil processes. During the first three years of the fallow formation, the soil became more firm. The unit weight of the arable layer reached 1.48 g/cm 3 , hardness reached 24.4 kg/cm 2 and water permeability reached 59 mm/hour. The soil’s ability to recover its initial parameters began after 7‐10 years and after 30 years of fallow formation, the soil firmness was the same as in the steppe area, the unit soil weight acquired an equilibrium state, and the water permeability of the soil became optimal. Conclusion . In the first 3‐4 years after the assignment of an area for fallow, it is optimal to mow plants twice or three times before their seeding, using mowed biomass for green manure or composting. In the next 4‐7 years, moderate grazing or mowing is recommended. Fallows over 8‐10 years old are used for grazing and haying.