Changes in soil organic carbon fractions in response to wheat straw incorporation in a subtropical paddy field in China

Abstract

Background: Optimal wheat straw management in paddy fields is important for evaluating soil organic carbon (SOC) dynamics and sustaining soil quality. Aims: We investigated the effects of wheat straw incorporation in paddy soil on the total SOC content, soil labile organic C fractions [water soluble organic C (WSOC), hot‐water soluble organic C (HWSOC), easily oxidizable C (EOC), microbial biomass C (MBC), particulate organic C (POC), and light fraction organic C (LFOC)], and C pool management index (CPMI). Methods: Rice (var. Qingjiao 307) was grown from June to November 2019 in a subtropical paddy field, under four different treatments: without any amendments (control; CK); with N, P, and K fertilizers (NPK); with NPK and a moderate rate of wheat straw application (NPKS1); and with NPK and a high rate of wheat straw application (NPKS2). Soil samples were collected from depths of 0–5, 5–10, 10–20, and 20–30 cm after the rice was harvested. Results: In all soil layers, the bulk density was 10.79–51.85% lower and the total SOC, WSOC, HWSOC, EOC, MBC, POC, and LFOC contents were 13.87–145.97% higher in the NPKS2 treatment than in the CK treatment (p < 0.05). The CPMI was highest in the NPKS2 treatment in the top 20 cm soil. SOC correlated positively with labile C fractions and CPMI in the 0–5 and 5–10 cm soil layers (p < 0.05), with the exception of WSOC and LFOC in the 5–10 cm soil layer. The sensitivity of each soil labile organic C fraction to the different treatments varied in the 0–5 cm soil layer. Rice yield was highest in the NPKS2 treatment. Conclusions: Overall, the NPKS2 treatment had a positive effect on SOC stocks and higher soil quality in subtropical paddy soils in China.

Response of carbon and nitrogen dynamics in soil water‐stable aggregates to wheat straw incorporation in the Yangtze River Delta of China#

“…In this study, the rice grain yield and yield components were highest in the HSNPK treatment and lowest in the control. Similar outcomes have been found in other studies (W. Dai, Gao, et al., 2021; Xia et al., 2014; P. Zhang et al., 2015). In addition, we observed that rice grain yield was positively correlated with SOC and TN at a depth of 0–30 cm; these results verified that SOC and TN are pivotal parameters for crop growth (N. Liu et al., 2021; P. Zhang et al., 2015).…”

“…In this study, the rice grain yield and yield components were highest in the HSNPK treatment and lowest in the control. Similar outcomes have been found in other studies (W. Dai, Gao, et al, 2021;Xia et al, 2014;P. Zhang et al, 2015).…”

“…P and K fertilizers were applied 120 and 150 kg ha -1 , respectively, in the basal fertilizer stage. Other field management practices were in line with those depicted by W. Dai, Gao, et al (2021).…”

“…The summer rice–winter wheat is the dominant rotation system in this region, which produces high grain and straw yields, and straw incorporation has been promoted for this cropping system (X. Wang et al., 2015). Previous studies have reported the effects of straw incorporation on changes in bulk SOC and TN contents and crop productivity in this region (W. Dai, Gao, et al., 2021; Yu et al., 2020). However, information about the aggregate formation and the contents of OC and TN in different aggregates at different soil depths under wheat straw incorporation practices remains unclear, especially in paddy soils, as the management of paddy soils develops an environment conducive to the soil C and N formation and differs greatly from the environment in upland soils (Qi et al., 2021).…”

Wheat Straw Incorporation Affecting Soil Carbon and Nitrogen Fractions in Chinese Paddy Soil

“…In addition, 90 kg N ha −1 was top-dressed in the tillering and panicle initiation stages. Detailed information on agronomic management has been previously described [18].…”