Effect of polyaspartic acid on soil water storage, soil microbial diversity, cotton yield and fiber quality

Water-saving is one of the most important problems in agricultural development, especially in arid and semi-arid areas. The effects of polyaspartic acid (PASP) on soil water storage, soil microbial community, soil physiochemical properties, cotton yield and fiber quality were studied to find water-saving material utilized in cotton field. The experiment was divided into two parts, the first part concerned the direct application of three different amounts of PASP under field conditions. In the second part, PASP was mixed with soil in different proportions and the mixtures were put into bottles, which were then buried in the cotton field. The application of PASP improved the water-holding capacity and thus increased water content available to the cotton root system in the cotton field for a long time, and significantly (p < 0.05) increased the content of soil organic matter, available P and ammonium-N. Relative abundances of Methylophaga, Sphingomonas, Cupriavidus, Pseudeurotium, Fusarium and Nectria were significantly affected by applying PASP. Compared to the control group, 15, 75 and 150 kg ha^-1 of PASP increased seed cotton yield by 3.94, 8.31 and 7.71%, respectively. The application of PASP also increased the reflectance degree, Micronaire and short fiber index of cotton. These results suggested that 75 kg ha^-1 of PASP can be appropriate to alleviate drought stress in arid and semi-arid areas.