Choice of the irrigator disposition depth into the mole irrigation system in the lower Volga Region

Researches to study the features of mole irrigation technique were carried out in 2022 on the experimental fields of the Educational Research and Production Center of the Volgograd State Agrarian University «Gornaya Polyana». The article shows the rationale for choosing the depth of the of mole sprinkler location based on the analysis of the features of the moisture contour formation in the soil after irrigation and the assessment of possible water filtration below the active soil layer.

Introduction. Currently, in many regions of our planet there is an acute shortage of fresh water for irrigation. In this regard, the most water-saving method of irrigation is subsurface irrigation and, its main variety, mole irrigation. This method of irrigation has all advantages of subsoil irrigation (supply of fertilizers and irrigation water directly to the root system, no evaporation, significant savings of irrigation water) with minimal financial and technical resources for setting up an irrigation network. In this regard, the study of the features of mole irrigation technique has the scientific and practical interest.

Object. The depth of the irrigators location in the mole irrigation system.

Materials and methods. Field experiments were carried out in 2022 on light chestnut soils of the Lower Volga region. The purpose of the research was to scientifically and experimentally substantiate the technical parameters of the mole irrigation system. One of the main tasks was to study the nature of the distribution of moisture in the soil and the degree of deep filtration at different depths of molehills. For this, 3 options for the depth of the mole sprinklers location were studied (0.3; 0.4 and 0.5 m) in three zones: waterlogging (˃ 110% of the Lowest moisture capacity), normal (90 ... 110% of the Lowest moisture capacity) and low moisture (75 ... 90% of the Lowest moisture capacity). Such observations were made several times during the irrigation season. The article presents the most typical arrangements of moisture isopleths in the soil profile. The diameter of the molehills was the same in all variants and was within 58…63 mm. The irrigation rate was 200 m3/ha, and the volume of water supply to 1 molehill with its length of 75 m was 2 m³.

Results and conclusions. The results of the research showed that the depth of mole irrigation systems of 0.3 ... 0.4 m made it possible to more effectively moisten the active soil layer of 0-0.8 m without of deep filtration into layers below 0.8 m, because one day after irrigation the zone of normal moistening was 95.1…99.3% in the active layer, and its boundaries spread from above to a depth of -12…-18 cm and -83…-88 cm from the bottom of the earth's surface. It was also found that the depth of the molehills did not affect the lateral distribution of moisture. The zone of normal moisture, on average, according to the variants of the experiment, extended by 46.0 cm to the left and 44.0 cm to the right, and the zone of low moisture - by 78.7 cm to the left and 65.0 cm to the right of the molehill axis. Therefore, mole sprinklers can be placed under each row of plants if they are at a distance of 1 m or more from each other.

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