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Field cultivation practices have changing the carbon and nitrogen cycles in farmland ecosystem, soil organic carbon (SOC) and total nitrogen (TN) were the important pa- rameters in maintaining soil quality and increasing agricultural productivity, however, N application's effects on the SOC and TN storage capacity under intensive wheat- maize cropping system remain unclear. Therefore, we investigated the characteristics and relationships of SOC and TN for wheat-maize cropping system under nitrogen treatments. In doing so, continuous applications of four nitrogen application rates were examined: 0, 180, 240 and 300 kg ha-1 (N0, N180, N240 and N300, respectively). Wheat yields under N180 and N240 were significantly higher than that under N300, while the maize yields under N180, N240 and N300 were significantly higher than that under N0 by 79.79, 85.23 and 86.85%, respectively; the TN content and storage were significantly higher under N240 than that under other N levels in 40-60 cm soil layer after wheat growing season; the SOC content and storage under N180 and N240 were significant higher than that under N300 in 20-40 cm after maize growing season. The correlations between SOC and TN contents (or storage) were stronger after wheat planting than maize planting. These findings provide a basis for further studies on the effect of long-term N application on SOC and TN storage, crop quality and nitrogen use efficiency under wheat-maize cropping systems. [ABSTRACT FROM AUTHOR]

Soil CO 2 emissions respond differently to different tillage practices. However, limited information is available regarding the impact of conventional tillage (CT) and no-tillage (NT) on soil CO 2 emissions and the primary controlling factors or processes. The goal of this study is to derive the relationship of soil CO 2 emissions with soil physicochemical properties from differently tilled soils in a typical winter wheat summer maize rotation system. We hypothesized that soil tillage practices would impact the soil carbon cycle by modifying soil physical and chemical properties, which would in turn affect the soil CO 2 emissions. The study was conducted from 2018 to 2022 with two tillage practices using a randomized complete block design with three replicates. A leading international real-time monitoring system in situ was used to collect soil CO 2 emission data. Cumulative soil CO 2 emissions were reduced by 28.7% in maize and increased by 9.0% in wheat under NT as compared to CT. On an annual scale, the cumulative CO 2 emissions were decreased by 20.5% in NT as compared to CT. Maize season accounted for 70% 78% of soil CO 2 emissions. NT improved the aboveground biomass by 7.74% and 6.44%, and grain yields by 10.2% and 4.49% for maize and wheat, respectively. The soil CO 2 emission intensity of maize was reduced by 35.9% under NT as compared to CT. No significant differences were discovered under the two tillage practices for soil CO 2 emission intensity of wheat. For maize, NT increased the bulk density, subsequently decreasing soil temperature and increasing soil moisture. NT also led to higher soil organic carbon and total nitrogen content, ultimately resulting in a significant reduction in soil CO 2 emissions. For wheat, NT increased soil bulk density, further increasing soil moisture and lowering soil pH. NT thus resulted in lower soil organic carbon and total nitrogen content, ultimately leading to enhanced soil CO 2 emissions. Some of these observations might not be consistent with theoretical predictions, which indicated that the unconsidered factors of actual field conditions might have much significant effects. Overall, NT can be extensively used as an eco-friendly cropland tillage practice based on its positive effects of reducing CO 2 emissions and increasing crop yields. [Display omitted] • CO 2 emission variations by tillage were evaluated by the structural equation model. • No-tillage (NT) decreased CO 2 emissions by 28.7% in maize and increased by 8.99% in wheat. • Annual CO 2 emissions were decreased by 20.5% under NT than conventional tillage (CT). • Maize season accounted for 70% 78% of soil CO 2 emissions. • CO 2 emission intensity of maize was reduced by 35.9% under NT compared with CT. [ABSTRACT FROM AUTHOR]