EFFECTS OF GYPSUM COMBINED WITH DIFFERENT AMOUNTS OF BIOCHEMICAL HUMIC ACID ON SOIL IMPROVEMENT AND COTTON (GOSSYPIUM HIRSUTUM L.) YIELD ON SALINE-ALKALI LAND

This study was conducted to investigate the effects of gypsum combined with different amounts of biochemical humic acid (BHA) on the improvement of saline-alkali soil and cotton (Gossypium hirsutum L.) yield under film-mulched drip irrigation in Shaya County, Aksu Prefecture, Xinjiang, China.Using the micro zone test method, taking the single application of gypsum as the control (CK, gypsum 15 t•ha -1 ), 3 ratios of BHA were applied: A (gypsum 15 t•ha -1 + BHA 0.35 t•ha -1 ), B (gypsum 15 t•ha -1 + BHA 0.75 t•ha -1 ) and C (gypsum 15 t•ha -1 + BHA 1.50 t•ha -1 ).The results showed that the combined application of gypsum and BHA significantly reduced soil pH and electric conductibility, while increased soil porosity.Compared to the control, the large aggregates (>0.25mm) in 0-10 cm and 10-20 cm soil layers of the three treatments increased by 10.00%, 20.33%, 33.68% and 7.39%, 20.61% and 25.00%, respectively.Besides, the content of Na + in topsoil decreased significantly, while the content of Mg 2+ increased obviously.In addition, the cotton yield increased by 5.86%, 12.50% and 18.13%, respectively compared with the control.Considering the yield investment ratio of agricultural production and the comprehensive effect of soil improvement, the combined application mode of gypsum 15 t•ha -1 + biochemical humic acid 1.50 t•ha -1 had the best result among all three treatments.