The Effect of Cotton Monoculture and Alfalfa Crop Rotation of on Soil Microbiological Properties

Abstract

The article describes the microbiological state of the soil in a long-term field experiment of a cotton monoculture and cotton-alfalfa crop rotations for many years (since 1926) under conditions of typical gray soils in the central experimental farm of the Research Institute of Agrotechnologies for Breeding, Seed Growing and Cotton Cultivation (RIABSGCC). The soil samples were taken at the beginning of cotton growing (spring) before the start of the experiment and at the end of cotton growing (autumn) and the amount of ammonifiers, phosphorus-decomposing bacteria, oligonitrophils, nitrogen fixers, micromycetes, actinomycetes from the studied active agronomic groups of microorganisms was determined. According to the results of scientific studies, nitrogen-fixing microorganisms in the soil were not found either in samples taken at the beginning of the application period, in spring, or in samples taken at the end of the application period in autumn. Decomposing bacteria were found in all variants at the beginning of the season. However, it was increased by the end of the application period in the 1st variant (a cotton monoculture, 30 t/ha of manure + 25 kg/ha of R2O5 (since 1926)). In the variant 4, it remained low rate of mineral fertilizers (a cotton monoculture NRK 150:100:75 kg / ha (since 1926)), and in other cases it was not found, it was stated that the number of oligonitrophils reduced in all variants, similar data were noted in micromycetes.