Effects of different tillage management on rhizosphere soil nitrogen mineralization and its extracellular enzyme activity in a double‐cropping rice paddy field of southern China

Abstract

Soil 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.

Impact of Tillage and Straw Management on Soil Properties and Rice Yield in a Rice-Ratoon Rice System

“…BG regulates the release of soil glucose, and UR regulates the decomposition of urea, both of which are important enzymes in soil C and N cycles [47,48]. We observed that tillage increased the activity of BG and UR, which was consistent with previous conclusions [49]. In this study, tillage increased SOC content, thus stimulating the synthesis of BG and UR [50].…”

“…Returning straw provides more substrates and energy sources for enzyme synthesis [53]. PT combined with returning straw had higher BG and UR at the tillering stage of rice in the main season, which may be because tillage fully mixed the straw and soil, which promoted the decomposition of straw and the synthesis of enzymes [49].…”

Effects of Short-Term Tillage on Rhizosphere Soil Nitrogen Mineralization and Microbial Community Composition in Double-Cropping Rice Field

“…, soil N, SOM contents) were enhanced under tillage and crop straw input conditions [ 19 ], which suggests that SOM provides more soil nutrients for rice. Furthermore, our results proved that soil N mineralization rates with RT and CT treatments were higher than that of NT treatment, indicating that soil chemical properties (soil N and SOM contents) were deficient with no-tillage and crop straw input treatments [ 4 , 20 ]. Meanwhile, our results proved that soil N transformation rates in rice field with CT treatments were higher than that of RT treatment, which suggested the existence of higher levels of soil soluble N, and a larger soil active N pool in rice fields under conventional tillage condition, in addition to improved quality of SOM with crop straw input practice.…”

“…The information regarding method and number of rhizosphere soil samples followed that reported by Tang et al . (2021) [ 4 ]. All soil samples were divided into two parts after removing the foreign matter ( e.g.…”

“…It is usually accepted that soil N mineralization in rice field changes with tillage practices. Previous studies found that both soil aerobic and anaerobic N mineralization rates in rice field with tillage managements were increased [ 4 ]. Soil potential for mineralizable N and maximum nitrification rate were enhanced under different tillage practice conditions [ 5 ].…”