Effect of the irrigation regime of rise on soil oxidation-reduction status

Abstract

During the cultivation of rice in the field for 3 months, the required water layer is maintained. In these conditions, there are the processes that lead to changes in the composition of organic and mineral components of the soil, namely: removal of easily soluble substances and mobile forms of nutrients, the dominance of reduction processes over oxidation ones. Irrigation of rice crops using drip irrigation also causes changes in salt and water-air regimes, which leads to the formation of salt bags and toxic salinization of the soil in a layer of 0-60 cm. The negative effect of drip irrigation is not so noticeable compared to flooding conditions and can be eliminated by observing crop rotation with the rate of the main crop not more than 50%. The research was conducted during 2016-2020 in the territory of the Rice Institute of NAAS and its experimental farm (Skadovsk district, Kherson region), where the soil cover is represented by dark chestnut saline soil. The study of the effect of rice cultivation in flood conditions was carried out on a rice irrigation system with an area of ​​190 ha, and under drip irrigation - on a demonstration trail with an area of ​​4 ha. The oxidation-reduction status of the arable soil layer of rice crop rotations when rice growing, is seasonal. In the period of water layer maintaining in the field, in the arable layer reduction processes predominate, while after harvesting and checks draining the intensity of the reduction processes is moderate and decreases. A model describing this process by the equation of a quadratic parabola was constructed. Growing rice under drip irrigation also reduces the oxidation-reduction soil capacity to negative values, but for a short period, which does not adversely affect the soil. The dynamics of this indicator in the conditions of drip irrigation is described by the equation of a quadratic parabola. Continuous monitoring of this process enables to evaluate the stability of fluctuations of the oxidation-reduction soil balance, which is important for assessing soil quality.