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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]

The land surface characteristic influences climatic environments by controlling the land surface energy and water fluxes. Although large progresses have been made in coupling detailed crop models into land surface models, there is much room left for improved estimates of surface fluxes in double cropping system, such as the winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) system under intensive influences of climate change and human activities in the North China Plain (NCP). Here, we modeled the growth and surface fluxes in winter wheat–summer maize double cropping system in the NCP through modified SiBcrop model. The parameters related with the crop growth in winter wheat and maize sub-models were emphasized to better simulate the seasonal dynamics of phenology phase, leaf area index (LAI), and latent (LH) and sensible (SH) heat fluxes. Observational data for phenology, LAI, and energy fluxes were compiled from Yucheng and Guantao stations, to calibrate and validate the SiBcrop model. The results showed that the adjusted SiBcrop captured better the seasonal dynamics of phenology, LAI, LH, and SH, relative to the original code. The largest biases in model results were in SH when horizontal advection prevails and in LH when there is summer maize senescence. Sensitivity analysis illustrated that growth duration, emergence date, LH, SH, and Bowen ratio were quite sensitive to sowing date of wheat, and growth duration and emergence and harvest dates to sowing of maize. The calibrated SiBcrop also simulated the LH and SH well at Guantao station. The adjusted SiBcrop is capable of assessing the responses of surface biophysical processes to the changes of human management and climate change in the double cropping system in the NCP. [ABSTRACT FROM AUTHOR]

The North China Plain (NCP) is an important production base for wheat (Triticum aestivum L.) and maize (Zea mays L.) in China, but intensive continuous winter wheat and summer maize (WM) double-cropping system (control) has also created the high carbon footprint (CF) ecological problems. It is imperative to build a new rotation pattern that not only achieves direct and indirect low greenhouse gases (GHG) emissions, but also takes into account the grain security. CF metrics (per unit area (CF a), per unit economic output (CF e) and per unit kg grain yield (CF y)) were calculated for a two-year crop rotation experiment established at the Wuqiao Experimental Station, from October 2016 to September 2018. The treatments were eight alternative crop sequences grown in the first year, followed by WM in the second year. Alternative crop sequences included (1) WM, (2) fallow, (3) spring maize, (4) winter wheat, (5) spring sweet potato (Dioscorea esculenta (Lour.) Burkill), (6) spring peanut (Arachis hypogaea Linn.), (7) winter wheat-summer peanut, and (8) potato (Solanum tuberosum L.) - silage maize. The results showed that fallow → WM and winter wheat → WM were weak absorption sinks of net GHG, and other rotation patterns were all net sources during the experimental period, while the seven rotation patterns could attain 48%–94% of grain crops yield in control. Spring sweet potato → WM and winter wheat - summer peanut → WM, had no significant differences with control from three different CF perspectives. Spring maize → WM, spring peanut → WM, and potato - silage maize → WM produced more CF than control. Therefore, fallow and planting winter wheat alone in the first year of novel two-year rotation patterns reduced CF in the NCP, planting spring sweet potato and winter wheat-summer peanut increased net income without increasing CF and without compromising grain security, which could attain 1.53 and 1.12 times of the control. The research preliminary showed that winter wheat → WM, spring sweet potato → WM and winter wheat - summer peanut → WM were feasible to trade off of grain production and reducing CF. • Exploring the novel rotation patterns and trying to ensure grain security while reducing carbon emissions. • Compared with winter wheat and summer maize (WM), fallow→WM and W→WM were weak absorption sinks and required fewer resources. • Spring sweet potato→WM and W-summer peanut→WM increased net income, without increasing CF and compromising grain security. [ABSTRACT FROM AUTHOR]