It is established that economically justified irrigation rate is directly proportional to productive soil moisture content at saturation to the lowest moisture capacity, and it rises with the increase of irrigation costs and decreases at the increase of difference between market value of irrigated crop and its cost. Specific feature of the ecological-economic optimization task is to take into account technological and ecological limitations of irrigation regime. Besides additional net income received from irrigation, the value of optimal irrigation rate should be higher than the technological minimum connected with the total time spent on the maintenance of irrigation system and on idle relocation of irrigation equipment in the process of watering and should not exceed the environmentally acceptable limit, excluding irrigation water losses due to surface and subsurface runoff. Compliance with these conditions allows to make a choice between drip irrigation or sprinkling as the methods of crop irrigation.

The characteristics of hose sprinkling machines and hydraulic feeders are analyzed. A dependence is proposed for calculating the flow rate of the dosing device for the purpose of fertigation. An example is given of calculating the supply of microfertilizers for hose sprinkling machines at a specific dose of 1 l/ha of the applied preparation. Based on the calculation, a variant of the hydraulic feeder was selected. The technical efficiency of a standard hydro-feeding solution is analyzed and a method for its implementation with greater manufacturability is proposed.

The rationale is given for the need to develop promising, more effective design solutions for draining low relief elements on poorly permeable soils, taking into account the dynamics of the movement of surface and ground waters along the arable and subsurface horizon. It is proposed to use a drainage geocomposite in the form of a profiled membrane in the water-absorbing elements of reclamation systems for this purpose. Their hydraulic characteristics are noted. The technique and results of testing the membrane in a hydraulic flume are presented. It is indicated that the membrane protrusions have a significant effect on the increase in pressure losses and the reduction in flow compared to a smooth surface. The values of the roughness coefficient calculated by various formulas are given. The possibility of using geomembranes in water-absorbing devices - absorber columns is substantiated.

The article considers empirical data on the influence of aquatic and near-water vegetation on the level regime of the canal during the period of minimum flow. Based on field studies in the HEC-RAS environment and the Chezy formula, simulation models were selected. Using a simulation model, numerical experiments were carried out to obtain new knowledge in the field of understanding the influence of aquatic vegetation on the parameters of a watercourse. The results obtained allow us to conclude that the existing water associations during the period of minimum flow are capable of creating significant hydraulic resistance along the canal bed and more than doubling the flow levels.

For the normal functioning of modern reclamation systems, it is of great importance to increase the stability of channel slopes and dams from destruction under the influence of a number of natural and artificial causes. The selection of grass mixtures for strengthening the slopes of reclamation channels, based on perennial rhizomatous grasses and rapidly developing loose-leaf cereals and legumes, is given. The norms of seeding are given, taking into account the features of the slope, providing reliable stability and durability of reclamation systems.

On the gray-brown soils of the southern foothill part of the Mugan steppe, the manifestation of irrigation erosion on cotton crops was studied. It has been established that the slope and mesorelief of the plot have a great influence on the erosion of the furrow, than the magnitude of the irrigation jet. As a result of irrigation erosion, the soil is depleted of humus and gross forms of nutrients, which in the erosion zone are reduced by 15‒20 % from the initial level before irrigation. The elements of the slope have a stronger influence on the growth, development and yield of cotton than the elements of the irrigation technique. Relationships between yield indicators between the degree of unevenness of the relief and the development of cotton have been established.

Some features of soil erosion in the Kura-Araz lowland have been studied, the main areas and directions of erosion, including those under cotton, have been identified. Prevention of irrigation erosion is a very difficult task in practice. As the flow of water increases, the washing out of the soil increases. Therefore, additional measures are needed to prevent this process, many of these activities serve to increase soil resistance to erosion: the application of crop rotation, pre-wetting and the use of ameliorants, polymeric and ionomer materials to increase soil resistance to erosion.

The results of long-term stationary field experiments on the study of crop productivity on sod-podzolic light loamy soils subject to water erosion located on the slopes of the southern and northern exposures are summarized. It has been established that winter grain crops reduce the yield on slightly washed soils from 0.21 to 0.75 t/ha (by 3–12 %), on medium and heavily washed soils it reaches 1.04 and 1.93 t/ha (17–21 %) respectively. On soils with the same degree of washout, the yield reduction on the slope of the northern exposure is more significant compared to the southern slope. The decrease in the yield of spring grain crops and spring rapeseed on slightly washed soils ranges from 0.05 to 0.46 t/ha or from 1 to 9 %. The shortage of yield of spring wheat and spring rapeseed on heavily washed soils reaches 21–22 %. The productivity of spring wheat, barley and spring rapeseed on the slope of the northern exposure is lower than on the slope of the southern exposure. Potato crop shortages vary depending on soil erosion in the range of 1.29-2.30 t/ha (5–8 %). The influence of the slope exposure is not as significant as in other cultures. Seed peas and alfalfa are most responsive to soil erosion. The decrease in the yield of peas on medium - and heavily washed soils is 0.69–0.73 t/ha of grain or 27 %, alfalfa – 15.42–18.50 t/ha of green mass or 22–30 %. The influence of soil erosion also depends on the slope exposure – on the slope of the northern exposure, the negative influence increases.