Wang Zhao-Hui, Chen Shu-Tao, Sun Lu, Hu Zheng-Hua
Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology(CICAEET), Nanjing University of Information Science and Technology, Nanjing 210044, China.
School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Huan Jing Ke Xue. 2018 Apr 8;39(4):1943-1951. doi: 10.13227/j.hjkx.201709009.
To investigate the effects of precipitation reduction on soil respiration in rainfed croplands, a field experiment was performed in a soybean-winter wheat cropland. A randomized block design including three treatments, viz. control (CK), 20% precipitation reduction (P20%), and 40% precipitation reduction (P40%), was used. Seasonal variabilities in soil respiration, soil temperature, and soil moisture were measured. Rates of soil CO production, nitrification and denitrification, and harvested crop biomass were also measured. Results indicated that the seasonal mean soil respiration rates for CK, P20%, and P40% treatments in the soybean growing season were (4.91±0.67), (4.19±0.39), and (4.35±0.32) μmol·(m·s), respectively. There was no significant difference (>0.05) in the mean soil respiration rates between treatments during the soybean growing season. The seasonal mean soil respiration rates for CK, P20%, and P40% treatments during the winter wheat growing season were (2.39±0.17), (2.03±0.02), and (1.94±0.05) μmol·(m·s), respectively. There was a significant (<0.05) difference in the mean soil respiration rates between treatments during the winter wheat growing season. Precipitation reduction decreased the soil CO production rates, but had no obvious impacts on soil nitrification and denitrification rates. Precipitation reduction had no significant (>0.05) effects on the root, shoot, and seed biomass of soybean, but significantly (<0.05) decreased the root, shoot, and seed biomass of winter wheat. Soil temperature was the main driver of the seasonal variation in soil respiration. Soil respiration increased exponentially with the increase in soil temperature. There was no significant (>0.05) difference in the coefficient of temperature sensitivity () between different treatments. Based on the precipitation reduction experiments of duration longer than one year in previous studies and in our present study, a significant linear regression relationship between the amount of reduced soil respiration and the amount of precipitation reduction was found, indicating that substantial precipitation reduction showed more obvious inhibition effects on soil respiration. This study also suggested that the effects of precipitation reduction on soil respiration varied between crop growing seasons, which may be attributed to the different precipitation intensities in different growing seasons.
为研究降水减少对雨养农田土壤呼吸的影响，在大豆 - 冬小麦农田开展了田间试验。采用随机区组设计，包括三种处理，即对照（CK）、降水减少20%（P20%）和降水减少40%（P40%）。测定了土壤呼吸、土壤温度和土壤湿度的季节变化。还测定了土壤CO产生速率、硝化和反硝化速率以及收获的作物生物量。结果表明，大豆生长季CK、P20%和P40%处理的季节平均土壤呼吸速率分别为(4.91±0.67)、(4.19±0.39)和(4.35±0.32) μmol·(m·s)。大豆生长季各处理间平均土壤呼吸速率无显著差异(>0.05)。冬小麦生长季CK、P20%和P40%处理的季节平均土壤呼吸速率分别为(2.39±0.17)、(2.03±0.02)和(1.94±0.05) μmol·(m·s)。冬小麦生长季各处理间平均土壤呼吸速率存在显著差异(<0.05)。降水减少降低了土壤CO产生速率，但对土壤硝化和反硝化速率无明显影响。降水减少对大豆的根、茎和种子生物量无显著影响(>0.05)，但显著降低了冬小麦的根、茎和种子生物量(<0.05)。土壤温度是土壤呼吸季节变化的主要驱动因素。土壤呼吸随土壤温度升高呈指数增加。不同处理间温度敏感性系数()无显著差异(>0.05)。基于以往研究及本研究中超过一年的降水减少试验，发现土壤呼吸减少量与降水减少量之间存在显著的线性回归关系，表明大量降水减少对土壤呼吸的抑制作用更明显。本研究还表明，降水减少对土壤呼吸的影响在作物生长季间存在差异，这可能归因于不同生长季的降水强度不同。
