保护性耕作对农田生态系统净碳释放量的影响

Effects of conservation tillage on net carbon flux from farmland ecosystems

以华北平原小麦-玉米两熟地区保护性耕作5年田间定位试验为基础,利用West提出的净碳释放方程对翻耕、少耕和免耕3种耕作方式下农田各项投入造成的碳释放和土壤碳累积进行比较。结果表明:在翻耕、少耕、免耕3个处理下,5年间各项农田投入造成的碳释放分别为312.60、295.4和280.52kg.km-2.a-1,表层30cm土壤的碳储量分别为30.59、32.76和31.61Mg.km-2,农田净碳释放量分别为312.60、-138.59和-76.52kg.km-2.a-1;与翻耕地比较,免耕和少耕地的相对净碳释放量为-236.08和-451.19kg.km-2.a-1;免耕地农田投入的碳减排量(32.08kg.km-2.a-1)为土壤碳增汇量(204.00kg.km-2.a-1)的15.73%,少耕地农田投入的碳减排量(17.19kg.km-2.a-1)为土壤碳增汇量(434.00kg.km-2.a-1)的3.96%。少耕地对减少大气CO2的贡献大于免耕地。

Based on a 5-year field experiment in winter wheat-maize double cropping area and by using West function, this paper studied the net carbon （C） release from farmland ecosystems under different tillage practices. The results indicated that during the five years, the C release from agricultural inputs under conventional tillage （ CT）, reduced tillage （RT） and no-tillage （NT） was 312.60,295.41 and 280. 52 kg · km^-2·a^-1, while the C sequestration in 0-30 cm topsoil was 30.59, 32.76 and 31.61 Mg · km^-2, with a net C flux being 312.60, -138.59 and -76.52 kg · km^-2· a^-l, respectively. Compared with CT, the relative net C flux under NT and RT was -236.08 and -451.19 kg · km^-2 · a^-l The decrement of the C release from agricultural inputs under NT （32.08 kg · km^-2 · a^-1 ） was 15.73% of the increment of C sequestration （204.00 kg · km^-2·a^-1）, while that under RT （17.19 kg·km^-2 · a^-l ） was 3.96% of the increment of C sequestration （434.00 kg · km^-2· a^-1）. RT had a greater contri-bution than NT in the atmospheric CO2 reduction.