关键词: 棉秸秆; 堆腐; 氮肥; 磷钾肥; 失重率

Abstract: 【Objective】 To study the effects of exogenous nitrogen and phosphorus potassium fertilizers on the decomposition of cotton straw in the hope of providing a theoretical basis for the fertilization and matrix utilization of cotton straw.【Methods】 The net bag decomposition method was used to set up three treatments: natural decomposition of cotton straw, decomposition of cotton straw with nitrogen fertilizer (urea), and decomposition of cotton straw with phosphorus potassium fertilizer (potassium phosphate). The samples were collected at early stage (0-7 d), middle stage (7-14 d), late stage (14-21 d), and last stage (21-28 d). The cotton straw quality and cellulose, hemicellulose, lignin content were measured. Then the cotton straw cumulative weight loss and period weight loss rate, as well as the cumulative degradation rate and period degradation rate of the three fiber components were analyzed.【Results】 Adding nitrogen fertilizer could increase the cumulative weight loss rate of cotton straw, which was 6.7% higher than that of natural decomposition. After adding phosphorus potassium fertilizer, the weight loss rate of cotton straw was reduced by 6.3% compared with natural decomposition. After nitrogen fertilizer was added, the degradation rate of cotton straw decreased significantly in the early stage of decomposition compared with natural decomposition, and then the decomposition rate accelerated. The degradation rate of natural decomposition and phosphate potassium fertilizer treatment was the fastest in the early stage of decomposition, and it decreased significantly in the middle stage, and then increased slowly afterwards. Adding nitrogen and phosphorus potassium fertilizers could increase the degradation rate of cellulose, hemicellulose and lignin. At the end of decomposition, compared with natural decomposition, the cumulative degradation rate of cellulose by adding nitrogen fertilizer increased by 178.29%, and the addition of phosphorus potassium fertilizer increased by 47.82%; the cumulative degradation rate of hemicellulose by adding nitrogen and phosphorus potassium fertilizers was basically the same, whose increase was around 40.6%; The degradation rate of lignin increased by 9.13% and 59.6% respectively by adding nitrogen fertilizer and potassium phosphate. The fastest stage of cellulose degradation was the addition of nitrogen fertilizer at the end of decomposition, phosphorus potassium fertilizer at the later stage of decomposition, and CK at the early and middle stages. The fastest stage was at hemicellulose degradation stage and all three treatments were in the early stage of decomposition. The fastest stage of lignin degradation was found in the early and mid-stage stage.【Conclusion】 The addition of nitrogen fertilizer and phosphorus potassium fertilizer could promote the decomposition degree of cotton straw. The nitrogen fertilizer degradation degree was higher than that of phosphorus potassium fertilizer. The degradation tendency of nitrogen fertilizer on cotton straw was different from that of CK and phosphorus potassium fertilizer. Nitrogen fertilizer promoted cellulose degradation more than phosphorus and potassium fertilizers; The degree of promotion of the degradation of hemicellulose by nitrogen and potassium fertilizer was almost the same; The degradation of lignin was promoted more than that of nitrogen fertilizer, and the process of degradation was different.

Key words: cotton straw; compost; nitrogen fertilizer; phosphorus and potassium fertilizer; weight loss rate