目前关于农田耕作管理措施下，cbbL细菌对不同水平土壤碳饱和亏缺（SCSD）的响应机制仍不清楚。因此我们研究了长期免耕秸秆还田（NT）和常规耕作（CT）措施下，SCSD对cbbL细菌丰度和多样性的影响。结果表明，相比于CT，NT降低了SCSD，降低了cbbL细菌的丰度和香农指数，改变了cbbL细菌的群落结构。另外，土壤碳饱和和cbbL基因数量存在显著正相关关系，但是与cbbL基因多样性之间不存在相关关系。综上，低SCSD限制了cbbL细菌的丰度，但是对cbbL细菌的多样性没有影响。因此，关于cbbL细菌固碳速率和能力的研究，应该建立在耕作措施对cbbL细菌丰度和多样性影响的基础上。我们的研究揭示了土壤固定CO₂过程中生物机制和物理化学机制之间存在的关系，对于CO₂的固定机制研究具有重要意义。

以更少的环境代价生产更多的食物是当前全球面临的重要挑战。当前，地膜覆盖技术已成为农业生产中提高作物产量的重要措施，但其对作物生产温室气体排放的影响仍不清楚。本研究的主要目标是定量评价地膜覆盖对作物生产生命周期温室气体排放的影响，并提出相应的削减策略。本研究选取黄土高原春玉米农田作为研究地点，通过2015-2018年4年田间试验，对裸地栽培、常规地膜覆盖栽培和免耕一膜两用栽培体系下的单位面积、单位产量和单位经济产出碳足迹进行了系统评价。评价结果表明，与裸地栽培相比，常规地膜覆盖在4年田间实验中使玉米平均产量提高了24%，但同时使得单位面积碳足迹增加了69%，其中59%由地膜材料的投入引起，10%由地膜覆盖期间土壤N₂O排放增加引起。常规地膜覆盖所带来的产量增加并不能抵消其所引发的碳足迹增加，其使得单位产量和单位经济产出碳足迹均增加了36%。改常规覆盖栽培为免耕一膜两用栽培后，作物产量并没有降低，但由于地膜材料投入量、N₂O排放和机械燃油的降低，单位面积碳足迹降低了21%，单位产量和单位经济产出碳足迹降低了23%。与裸地栽培相比，免耕一膜两用栽培下的单位产量和单位经济产出碳足迹仅高出5%。这一研究表明减少地膜投入量对于低碳农业发展十分必要，而采用免耕一膜两用代替常规地膜栽培有望在保障作物高产的同时实现碳足迹的有效削减。

Understanding the potential drought characteristics under climate change is essential to reduce vulnerability and establish adaptation strategies, especially in the Huang-Huai-Hai Plain (3H Plain), which is a major grain production area in China.  In this paper, we investigated the variations in drought characteristics (drought event frequency, duration, severity, and intensity) for the past 50 years (1961–2010) and under future scenarios (2010–2099), based on the observed meteorological data and the Representative Concentration Pathway (RCP) 8.5 scenario, respectively.  First, we compared the applicability of three climatic drought indices: the standardized precipitation index (SPI), the standardized precipitation evapotranspiration index based on the Penman-Monteith equation (SPEI-PM) and the same index based on the Thornthwaite equation (SPEI-TH) to correlate the recorded agricultural drought areas.  Then, we analyzed the drought characteristics using ‘run theory’ for both historical and the future RCP 8.5 scenario based on the best performing index.  Correlation analyses between drought indices and agricultural drought areas showed that SPEI-PM performed better than SPI and SPEI-TH in the 3H Plain.  Based on the results of SPEI-PM, drought risks including duration, severity and intensity during 1961–2010 showed an decreasing trend.  However, under the RCP 8.5 scenario, drought is expected to rise in frequency, duration, severity, and intensity from 2010–2099, although drought components during the 2010–2039 are predicted to be milder compared with historical conditions.  This study highlights that the estimations for atmospheric evaporative demand would create differences in the prediction of long-term drought trends by different drought indices.  The results of this study can help inform researchers and local policy makers to establish drought management strategies.

    Pollution of residual plastic film in arable lands is a severe problem in China. In this study, the status of residual film and influential factors were investigated using the methods of farm survey in combination with questionnaires and quadrat sampling at a large number of field sites in Xinjiang Uygur Autonomous Region, China. The results showed that the amount of film utilization increased largely and reached to 1.8×10⁵ t in 2013. Similarly, the mulching area also substantially increased in recent decades, and reached to 2.7×10⁵ ha in the same year. According to the current survey, 60.7% of the sites presented a greater mulch residue than the national film residue standard (75 kg ha^–1), and the maximum residual amount reached 502.2 kg ha^–1 in Turpan, Xinjiang. The film thickness, the mulching time and the crop type all influenced mulch residue. The thickness of the film had significantly negative correlation with the amount of residual film (P<0.05), while the mulching years had significantly positive correlation with it (P<0.05). The total amount of residual film in Xinjiang was 3.43×10⁵ t in 2011, which accounted for 15.3% of the cumulative dosage of mulching. Among all the crops, the cotton fields had the largest residual amount of mulch film (158.4 kg ha^–1), and also the largest contribution (2.6×10⁵ tons) to the total amount of residual film in Xinjiang.

Crop consumptive water use is recognized as a key element to understand regional water management performance. This study documents an attempt to apply a regional evapotranspiration model (SEBAL) and crop information for assessment of regional crop (summer maize and winter wheat) actual evapotranspiration (ETa) in Huang-Huai-Hai (3H) Plain, China. The average seasonal ETa of summer maize and winter wheat were 354.8 and 521.5 mm respectively in 3H Plain. A high-ETa belt of summer maize occurs in piedmont plain, while a low ETa area was found in the hill-irrigable land and dry land area. For winter wheat, a high-ETa area was located in the middle part of 3H Plain, including low plain-hydropenia irrigable land and dry land, hill-irrigable land and dry land, and basin-irrigable land and dry land. Spatial analysis demonstrated a linear relationship between crop ETa, normalized difference vegetation index (NDVI), and the land surface temperature (LST). A stronger relationship between ETa and NDVI was found in the metaphase and last phase than other crop growing phase, as indicated by higher correlation coefficient values. Additionally, higher correlation coefficients were detected between ETa and LST than that between ETa and NDVI, and this significant relationship ran through the entire crop growing season. ETa in the summer maize growing season showed a significant relationship with longitude, while ETa in the winter wheat growing season showed a significant relationship with latitude. The results of this study will serve as baseline information for water resources management of 3H Plain.

Climate change will have important implications in water shore regions, such as Huang-Huai-Hai (3H) plain, where expected warmer and drier conditions might augment crop water demand. Sensitivity analysis is important in understanding the relative importance of climatic variables to the variation in reference evapotranspiration (ET0). In this study, the 51-yr ET0 during winter wheat and summer maize growing season were calculated from a data set of daily climate variables in 40 meteorological stations. Sensitivity maps for key climate variables were estimated according to Kriging method and the spatial pattern of sensitivity coefficients for these key variables was plotted. In addition, the slopes of the linear regression lines for sensitivity coefficients were obtained. Results showed that ET0 during winter wheat growing season accounted for the largest proportion of annual ET0, due to its long phenological days, while ET0 was detected to decrease significantly with the magnitude of 0.5 mm yr-1 in summer maize growing season. Solar radiation is considered to be the most sensitive and primarily controlling variable for negative trend in ET0 for summer maize season, and higher sensitive coefficient value of ET0 to solar radiation and temperature were detected in east part and southwest part of 3H plain respectively. Relative humidity was demonstrated as the most sensitive factor for ET0 in winter wheat growing season and declining relativity humidity also primarily controlled a negative trend in ET0, furthermore the sensitivity coefficient to relative humidity increased from west to southeast. The eight sensitivity centrals were all found located in Shandong Province. These ET0 along with its sensitivity maps under winter wheat-summer maize rotation system can be applied to predict the agricultural water demand and will assist water resources planning and management for this region.