Effects of the Addition of Straw and Biochar on the Activities of Soil Enzyme

In order to study the responses of soil enzyme activities to different exogenous carbon additions, the culture experiment was conducted by adding the straw and biochar whose mass fraction in soil was 0, 1%, 2%, 3%, 4% and 5%, respectively. The results showed that the promotion effect of the addition of biochar on soil pH, the contents of total carbon, total nitrogen, rapid available phosphorus, and rapid available potassium was greater than that with the addition of straw, but did not significantly affect the content of available nitrogen. The addition of straw significantly improved the activities of soil acid phosphatase (AP),β-glucosidase (βG), cellulolytic hydrolase (CBH),β-N-acetylaminoglucosidase (NAG) and peroxidase (PEO) (expect the addition rate of 1%). The addition of biochar significantly increased the activities of βG, CBH and PEO (expect the addition rate of 1%). The low addition amount (1% and 2%) significantly reduced the activities of AP and NAG, while the high addition amount (3%, 4% and 5%) significantly increased the activities of AP and NAG. The activities of AP, βG, CBH, NAG and PEO with the treatment of straw were respectively 4.08-8.12, 12.94-34.63, 2.95-61.81, 8.39-42.06 and 0.45-1.20 times of that treated with the same addition amount of biochar. The redundancy analysis showed that the available nitrogen was the main factor affecting the activities of soil enzyme. Therefore, the addition of straw was more beneficial to increase the activities of soil hydrolase, while the addition of biochar was more beneficial to increase the soil nutrients.