Effect Of Cotton Straw Incorporated Into Saline-alkali Soil On Physical, Chemical And Biological Properties

The study was conducted in coastal saline soil in Bin Zhou city in 2013 and 2014. The soil physical, chemical properties and microbial properties of 0~20, 20~40 and 40~60cm soil layer, and the yield and fiber quality of cotton were studied of the two treatments.The study aimed at providing theoretical basis for fertilizing of saline-alkali soil and popularization and application of cotton straw incorporated into soil.The main results were listed as follows. 1. Effect of cotton straw incorporated into saline-alkali soil on physical propertiesCompared with cotton straw not returned to soil treatment, cotton straw incorporated into soil significantly improved >0.25 mm aggregates percentage, decreased the <0.25 mm micro-aggregates percentage of 0~5、5~10 and 10~20cm soil layer. Cotton straw incorporated into soil significantly reduced the soil bulk density, improved the soil aeration porosity of 0~10, 10~20 and 20~30cm soil layer. Cotton straw incorporated into soil significantly improved soil total porosity of 0~10 and 10~20cm soil layer. Cotton straw incorporated into soil significantly reduced the soil water content of 0~20, 20~40 and 40~60 cm soil layer. 2. Effect of cotton straw incorporated into saline-alkali soil on chemical propertiesCotton straw incorporated into soil significantly reduced the total salt content and water-soluble sodium content of 0~20cm soil layer. Cotton straw incorporated into soil significantly reduced the soil pH of 0~20, 20~40, and 40~60cm soil layer. Cotton straw incorporated into soil significantly improved the soil organic matter content and available nitrogen conten of 0~20cm soil layer, significantly reduced the soil available phosphorus content of 0~20cm soil layer. Cotton straw incorporated into soil significantly improved the soil wate-soluble potassium, exchangeable potassium and non-exchangeable potassium content, had no significant effect on soil mineral potassium content. 3. Effect of cotton straw incorporated into saline-alkali soil on biological propertiesCotton straw incorporated into soil significantly increased soil bacteria, actinomyces number of 0~20cm soil layer, significantly reduced the fungi number of 0~20cm soil layer. Cotton straw incorporated into soil significantly improved the soil urease, invertase and catalase activity of 0~20cm soil layer. In cotton straw incorporated into soil treatment, soil respiration rate of 0~20cm soil layer was significantly improved. In 20~40cm and 40~60cm soil layer, there was no significant difference of each biological property between the two treatments. 4. Effect of cotton straw incorporated into saline-alkali soil on cotton growth and yieldCotton straw incorporated into soil significantly improved the cotton fruit node number in the bud stage and early flowering fruit stage, significantly reduced the rate of cotton boll shedding. The cotton plant height, the height and location of the first fruit branch improved after cotton straw returned, but the difference was not significant between the two treatments. Cotton straw incorporated into soil for two years significantly improved the single boll weight, boll number per plant, seed cotton yield and lint yield by 0.43 g, 1.64, 18.93% and 19.82% respectively. Cotton straw incorporated into soil for two years had no significant effect on the lint. Cotton straw incorporated into soil for two years significantly improved cotton fiber micronaire by 0.52, had no significant effects on fiber length, strength and uniformity.All in all, cotton straw incorporated into soil is helpful for the improvement of the saline-alkali soil structure and fertility, and can increase cotton yield. With the extension of the time of returning cotton straw, the improvement of soil and cotton yield are becoming more obvious. Therefore, cotton straw incorporated into soil should be popularizied and applicatied in coastal saline-alkali cotton growing area.