Effects of Cotton Stalk Returning on Soil Physical and Chemical Properties and Cotton Yield in Coastal Saline-Alkali Soil.

A A continuous three-year field experiment of cotton-residue incorporation in coastal saline-alkali land was conducted, with two treatments: residue removal and residue incorporation. The successive cotton stalk returning significantly decreased soil bulk density in 0-30 cm soil layer and soil micro-aggregates with particle size <0.25 mm in 0-10 cm soil layer, while significantly increased the content of soil macro-aggregates with particle size >5 mm in 0-10 cm soil layer. Compared with the control (residue removal), the treatment of cotton residues incorporation significantly increased soil organic matter, nitrate nitrogen, ammonium nitrogen and available potassium by 13.45%, 18.57%, 22.80%, and 22.57%, respectively, while decreased soil available phosphorus and salinity by 18.29% and 16.59% at pre-sowing and each growth stage in 0-20 cm soil layer. Soil nitrate nitrogen and ammonium nitrogen were increased by 37.20% and 31.62% and soil salinity had a reduction of 19.06% after successive cotton stalk returning for three years in 20-40 cm soil layer, and also significantly increased by 38.26% and 24.83% in 40-60 cm soil layer. Successive cotton stalk returning significantly increased seed cotton yield by 11.57%, 19.01%, and 13.24% and lint yield by 18.56%, 19.78%, and 18.73% in three years, but not affected single boll weight and lint percentage. [ABSTRACT FROM AUTHOR]