长期定位耕作方式下冬小麦田根系呼吸对土壤呼吸的贡献

为探讨长期定位耕作方式对冬小麦田土壤呼吸以及根系呼吸的影响，研究根系呼吸对土壤呼吸的贡献，基于设在山东农业大学农学实验站的长期保护性耕作定位试验（始于2002年），包括常规秸秆还田（PC）、免耕秸秆还田（PZ）、深松秸秆还田（PS）和旋耕秸秆还田（PR）4种处理，采用静态箱法测定和分析麦田土壤呼吸及水热因子，并利用根去除法研究根系呼吸对土壤呼吸的贡献。结果表明，不同耕作方式下根系呼吸与土壤呼吸的变化趋势相同，即在冬小麦整个生育期内，土壤呼吸与根系呼吸速率均呈“低-高-低”的趋势。各处理之间的土壤呼吸速率差异显著，与PC相比，PZ、PS、PR的土壤呼吸速率分别降低37.2%、17.0%、15.4%，PC、PZ、PR的根系呼吸速率较PS相比分别下降了9.4%、24.3%、22.4%。在冬小麦生育期内，根系呼吸占土壤呼吸的比例呈双峰型，比例波动为21.7%~82.0%，均值为49.1%，总体表现为PZ > PS > PR > PC。土壤呼吸与10 cm土层地温呈极显著正相关（P<0.01），而与土壤湿度未达到显著相关。研究表明，与PC相比，长期定位耕作方式中PZ和PS可以降低麦田的土壤呼吸速率，减少麦田土壤的碳排放，并且可以提高根系呼吸对土壤呼吸的贡献，其中PS的根系呼吸速率最高，更有利于作物的生长。

Contribution of root respiration to soil respiration in a winter wheat field under long-term localized tillage

To investigate the effects of long-term localized tillage on soil respiration and root respiration, and to study the contribution of root respiration to soil respiration in a winter wheat field, the long-term conservation tillage positioning experiment (started in 2002) was set up based on the Agricultural Experimental Station of Shandong Agricultural University. There were four treatments, namely, PC (Residue present & conventional tillage), PZ (Residue present & zero tillage), PS (Residue present & subsoil tillage), and PR (Residue present & rotary tillage). The soil respiration dynamic changes and the soil hydrothermal factors using static closed chambers and the contribution of root respiration with method of root exclusion during the growth period of wheat were measured. Soil respiration showed the same trend as root respiration under the different tillage systems, that is, soil respiration and root respiration showed a trend of "low-high-low" during the whole growth period of winter wheat. There were significant differences in soil respiration rates among different treatments. Compared with PC, the soil respiration rate of PZ, PS, and PR decreased by 37.2%, 17.0%, and 15.4%, respectively. The root respiration rate of PC, PZ and PR decreased by 9.4%, 24.3% and 22.4%, respectively, compared with PS. The contribution rate of root respiration to soil respiration was bimodal, with a fluctuation of 21.7%~82.0% (mean value of 49.1%), which were ranked as PZ > PS > PR > PC, the soil respiration was significantly positively correlated with soil temperature in 10 cm soil layer (P<0.01) and was not significantly correlated with soil moisture. Compared with PC, PZ and PS reduced the soil respiration rate of the wheat field, reduced the carbon emission of the wheat field soil, and increased the contribution of root respiration to soil respiration. The root respiration rate of PS was the highest, and was more conducive to the growth of crops.