黄淮海平原区不同农作措施下耕层土壤有机质矿化与CO_2排放估算

Estimation of Soil Organic Matter Mineralization in the Plough Layer and CO_2 Emission Under Different Farming Practices in China’s Huang-Huai-Hai Plain

黄淮海平原是中国重要的粮食产区,其中,小麦-玉米1年2作是其主要种植制度。集约农田土壤有机碳动态与管理对粮食可持续生产有着重要意义。应用修正的碳固持CQESTR模型,对黄淮海平原7个独立肥料长期定位点76个处理的10～20年土壤有机碳动态进行了模拟。结果表明,受有机物料还田水平的影响,黄淮海平原区农田耕层土壤有机质(SOM)年矿化速率差异较大,不同试验点多年平均最低值为2.16%,最高值为5.95%,各试验点平均而言,最低值仅占最高值的54.2%;这一数值随化肥用量和有机肥还田量的增加而增大,表现为SOM的数量与质量不断提高;耕层土壤CO2排放通量最低值为337.1gCO2·m-2·a-1,最高值为2144.3gCO2·m-2·a-1;各试验点多年平均而言,最低值仅占最高值的31.9%。统计分析表明,作物年产量增加1t·ha-1时,耕层SOM矿化排放通量提高96.5gCO2·m-2·a-1,耕层SOM矿化速率提高0.22个百分点;土壤年表观呼吸通量不仅反映土壤生物和植物代谢活动强度,还直观反映出耕层SOM的年矿化速率。

Huang-Huai-Hai plain is the most important region for grain production with winter wheat-summer corn rotation in one year as its dominating cropping system in China. Soil organic matter （SOM） dynamics and management in intensive agricultural soils is significant for sustainable crop production. Based on the 10-20-years data of 7 independent long-term soil fertility and fertilizer efficiency experiments total in 76 treatments, SOM dynamics in the plough layer were simulated by the modified CQESTR model. The results shows： the SOM mineralization rate （MR） in the plough layer increases with the magnitudes of annual organic inputs, indicating improvement in SOM quality, the inter-annual mean value of which ranges from 2.16% to 5.95% in the 76 treatments; at the respective sites the inter-annual mean MR of minimum is 54.2% that of maximum. Both quantity and quality of SOM will rise upon the increment of inorganic manure and/or organic manure applied. The inter-annual mean carbon dioxide flux （FCO2 mineralized from organic compounds in the plough layer ranges from 337.1 g CO2·m^-2·a^-1 of minimum to 2144.3.7 g CO2·m^-2·a^-1 of maximum, on the average the mean FCO2 of minimum is 31.9% that of maximum at the respective sites. Statistical analysis shows that MR enhances 0.22 percent point and FCO2 enhances 96.5 g CO2·m^-2·a^-1 when annual crop yield increases 1 t·ha^-1; the annual apparent soil respiration effiux （EFCO2） from whole soil profile reflects not merely the intensity of soil organism and plant metabolism, but the SOM MR in the plough layer with regression coefficient r^2 of 0.31 on 1235 pairs of data between MR and EFCO2.