Abstract

AbstractSoil extracellular enzyme activity plays an important role in regulating the process of nitrogen (N) mineralization in the paddy field. However, there is still limited information about how rhizosphere N mineralization and its extracellular enzyme activities respond to different tillage treatments in a double‐cropping rice paddy fields of southern China. Therefore, the effects of 6‐year (short‐term) tillage management on rhizosphere soil acid hydrolysable N and its fractions, N mineralization, and its extracellular enzyme activities in a double‐cropping rice paddy fields of southern China were studied and reported in this article. The field experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no‐tillage with crop residue retention (NT), and rotary tillage with crop residue removed as a control (RTO). The results showed that rhizosphere soil total acid hydrolysable N and its fractions with CT, RT and NT treatments were higher than those with RTO treatment. Compared to RTO treatment, the rhizosphere soil total acid hydrolysable N content with CT and RT treatments was increased by 19.17% and 17.74%, respectively. Compared to RTO treatment, the rhizosphere soil aerobic and anaerobic N mineralization rates with CT and RT treatments were increased by 100.00% and 80.65%, and 43.02% and 33.72%, respectively. Rhizosphere soil extracellular enzyme activities with CT and RT treatments were higher than those with NT and RTO treatments. There was a positive correlation between rhizosphere soil amino sugar N, amino acid N, total acid hydrolysable N contents, L‐glutaminase activity and N mineralization rate. The principal component analysis results indicated that rhizosphere soil organic carbon, amino sugar N, amino acid N and total acid hydrolysable N contents, soil β‐glucosaminidase, β‐glucosidase and L‐glutaminase activities were the main factors affecting rhizosphere soil aerobic and anaerobic N mineralization rates. As a result, rhizosphere soil acid hydrolysable N and its fractions, N mineralization, and its extracellular enzyme activities were significantly increased under the combined application of conventional tillage and rotary tillage with the crop residue incorporation condition.

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