Cotton irrigation regime under the mole irrigation method in the south of Russia

Abstract

Studies on developing optimal soil water regimes under mole irrigation of cotton compared with sprinkling and drip irrigation were conducted in 2023 on light-chestnut soils of southern Russia. As a result, it was found that under mole irrigation, with increasing the pre-watering threshold of soil moisture from 70-70-65 to 80-80-75 % of the lowest water holding capacity (LWC) irrigation rates decreased from 250...290 to 170...210 m3/ha and the number of irrigations and irrigation rate increased from 4 to 7 units and from 1040 to 1270 m3/ha. A comparison of irrigation methods showed that under mole irrigation, in comparison with drip irrigation, irrigation rates increased by 7.4. 13.3 %, and the number of irrigations per season and irrigation rate decreased by 1...2 units and 11.2...12.6 %, respectively. Compared to sprinkling, irrigation rates and total amount of water decreased by 45.2...46.3 and 28.8...34.5 %, respectively, and the number of irrigations increased by 1 unit. It was also found that maintaining a moisture availability level of 75-75-70 % LWC created optimal conditions in cotton crops, which, combined with mineral fertilizer application with doses N140P60K45, allowed the highest cotton yield under mole irrigation of 3.18 t/ha. When sprinkling on a similar option, it decreased by 0.21 t/ha, and at drip irrigation, it increased by 0.13 t/ha.