Effects of Cotton Straw Incorporation on Soil Microbial Biomass Carbon, Nitrogen and Phosphorus in Long-Term Continuous Cropping Cotton Field

This study explored the effect of straw incorporation on the content of soil microbial biomass carbon(SMBC), microbial biomass nitrogen(SMBN)and microbial biomass phosphorus(SMBP)in the continuous cropping cotton field. Results showed that cotton straw incorporation could increase the content of SMBC, SMBN and SMBP significantly in different soil layers. Besides, with the time of continuous cropping increasing, the content of SMBC, SMBN and SMBP were all remarkably raised in the straw incorporation treatment. However, with the time of continuous cropping increasing, the content of SMBC, SMBN and SMBP were all remarkably declined in the straw removal treatment.In 0 ~20 cm soil layer, compared with the straw removal, both SMBC content and SMBN content with 5, 10, 15 years continuous cropping treatments in the straw incorporation treatment were increased by 20.8%, 67.2%, 70.4% and 22.2%, 81.2%, 85.4%, respectively, and the SMBP content in the straw incorporation treatment was increased by 22.3%, 81.2%, 85.3%, respectively. Under the cotton straw incorporation, in 0~20 cm soil layer, compared with the 5, 10, 15, 20, 25 years continuous cropping, both SMBC content and SMBN content in 30 years were increased by 116.6%, 86.2%, 101.6%, 28.9%, 8.99% and 114.1%, 82.1%, 99.65%, 27.8%, 7.15%, respectively, and the SMBP content in 30 years was increased by 65.7%, 6.9%, 34.2%, 1.4%, 2.2%, respectively. The content of SMBC, SMBN, SMBP in different soil layers decreased in the order as 0~20 cm20~40 cm40~60 cm. Consequently, cotton straw incorporation could significantly increase the the content of soil microbial biomass carbon, microbial biomass nitrogen and microbial biomass phosphorus in the long-term continuous cropping cotton field, besides it could alleviate the negative impact of cotton continuous cropping, so that it would be beneficial to improve the soil quality and soil fertility.