Dynamics of soil properties under cotton - alfalfa crop rotation

The aim of the study: Monocrop cultivation is known to affect negatively soil physical properties and decrease soil fertility. To eliminate these undesirable consequences, application of mineral and/or organic fertilizers, as well as other agricultural practices, are employed. Other aspects of agronomy (soil cultivation, fertilizer and plant protection systems, the acquisition of new seeds) require significant material costs. Increasing the yield of agricultural crops, and cotton in particular, can be achieved by crop rotation. The aim of the study was to analyze some physico-chemical soil properties and dynamics of soil processes under cotton-alfalfa crop rotation. Location and time of the study. The research was carried out in 2014-2018 in the Northern Mugan in the Republic of Azerbaijan, as the region is one of the largest agricultural regions of the country, supplying cotton and grain. The studies were carried out on irrigated meadow serozem, or Endogleyic Calcisol, according to the WRB, soils of the Kura-Araks lowland of Azerbaijan. Methodology. Field and laboratory work was carried out according to generally accepted methods of soil science. The particle size distribution was determined by the pyrophosphate method; density, humus content, humidity, temperature, and morphological characteristics were determined using conventional methods. Statistical processing of the obtained data was carried out using the Microsoft Office Excel program. Main results. The long-term cotton crop was found to decrease agrophysical and agrochemical properties of soil. After three years of cotton production the humus content decreased by 20%, whereas the content of water-resistant aggregates increased by 40%, and soil permeability decreased three-fold, soil bulk density increased by 7%, all these resulting in the reduced cotton productivity. Crop rotation showed that soil fertility, decreased after three consecutive years of cotton growth, could be almost fully restored by following with two years of alfalfa crop. Conclusion. Compared with a monoculture of crops, crop rotation leads to a rearrangement in soil microflora and a change in soil biological and biochemical activity, helps to reduce the possibility of a unilateral influence of plants on soil, which in turn helps to restore soil fertility and obtain high sustainable crop yields in the cotton system. Therefore, the use of cotton-alfalfa crop rotations is very important for attaining the goal of increasing two-fold the production of all types of feed in Azerbaijan. To maintain potential fertility, obtain high sustainable yields of soil-protective, resource-saving crops, five-field cotton-alfalfa crop rotation is recommended for the farmers of the Mugan steppe.