EFFECTS OF POTASSIUM HUMATE ON COTTON (GOSSYPIUM HIRSUTUM L.) GROWTH AND YIELD AND SOIL SALINITY UNDER FILM-MULCHED DRIP IRRIGATION WITH BRACKISH WATER IN NORTHWEST CHINA

Soil salinity and poor soil structure are the main limitations of the agricultural economy in arid areas. The objectives of this study were to investigate the effects of different potassium humate amounts on cotton growth, seed cotton yield, water use efficiency and soil salinity under film-mulched drip irrigation with brackish water. The results showed potassium humate affected salt accumulation and the salt accumulation rate of potassium humate treatments (2.5, 5, 10, 15, 20, and 30 kg center dot ha-1) within 0-40 cm soil depths was 63.0%, 67.9%, 68.9%, 70.5%, 75.4%, and 100% lower than the untreated soils. Potassium humate application significantly enhanced the proportion of soil macro-aggregates and the mean weight diameter of water-stable aggregates. Potassium humate significantly increased cotton stem diameter, boll number per plant, plant height, and leaf area index compared to the control. Furthermore, the cotton yield and water use efficiency increased significantly. The potassium humate application amount of 20.5 kg ha-1 was recommended as an optimal potassium humate amount of saline soils from the point of view of water saving. The potassium humate application amount of 30 kg center dot ha-1 was recommended as an optimal potassium humate amount of saline soils from the point of view of improving soil quality.