摘要
应用14 C示踪技术研究了杂交狼尾草秸秆在稻麦轮作田中为期 1年的原位分解。结果表明 :秸秆用量对其分解率影响甚微 ,1年后秸秆C分解了 72 %左右 ,分解速率常数为 2 7× 1 0 - 3d- 1,但秸秆用量的多少与土壤原有碳的分解和土壤有机碳平衡密切相关。黄棕壤原有C年分解率为 5 4 5 %～ 6 0 7% ,分解速率常数在 1 0 4× 1 0 - 4～ 1 1 8× 1 0 - 4d- 1之间。随秸秆用量增加 ,黄棕壤原有C分解率和分解量均增加 ,土壤有机碳的亏缺减少。微生物量14 C占加入秸秆14 C的 3 79%～ 1 0 63% ,占土壤残留14 C的 1 2 2 7%～1 7 4 3% ,其大小变化及减少程度均较微生物量12 C显著。微生物量12 C约为微生物量14 C的 0 74～ 3 85倍 ,说明大多数情况下 ,土壤原有C仍是土壤微生物活动所需能量和养分的主要来源。微生物量14 C的周转率在 1 1 0～ 1 1 8a- 1之间 ,微生物量12 C的周转率在 0 97～ 1 0 6a- 1之间。增加秸秆用量可加快土壤微生物量C的周转速度 ,反过来微生物量C周转速度的加快又加速了秸秆C和土壤原有C的分解。土壤原有C和秸秆C的分解进程与微生物量12 C和微生物量14 C的动态变化趋势一致 ,说明有机碳分解的快慢是土壤微生物活动强弱的外在表现。
Decomposition of hybrid elephant straw 14C in situ in the field was studied using the 14C-tracer technique in yellow-brown earth under a wheat-rice rotation system for one year. Results indicated that the amount of straw added had little effect on its decaying rate. After one year,straw 14C decomposed by about 72% with a decaying rate constant of 2.7×10 -3 d -1. However, straw addition was closely related to decomposition of native soil C and balance of soil carbon. Soil native carbon decomposed by 5.45%～6 07% annually with a decaying rate constant from 1.04×10 -4 d -1 to 1.18×10 -4 d -1. With straw addition, decomposition of straw 14C increased in both amount and rate, while the net loss of soil organic C decreased. Biomass 14C accounted for 3.79%～10.63% of input 14C and 12.27%～17.43% of soil residual 14C. Its variation was much significant than that of biomass 12C. The ratio of biomass 12C to biomass 14C varied from 0.74 to 3.85, which indicated that under most situations, native soil C was still the major source of energy and nutrients for microorganisms. Turnover rates of soil biomass 14C and 12C were 1.10～1.18 a -1 and 0.97～1.06 a -1 respectively. Straw addition could accelerate turnover of soil organisms, and in turn increase in the turnover rate of soil organisms accelerate the decaying rate of straw C and soil native C. Decomposition processes of soil native C and straw C showed similar trends to dynamics of soil biomass 12C and soil biomass 14C, which indicated that decomposition rates of organic C were the apparent indication of activity of soil organisms.
出处
《土壤学报》
CAS
CSCD
北大核心
2003年第3期446-453,共8页
Acta Pedologica Sinica
基金
国家自然科学基金重点项目 (编号 :39830 2 2 0 )资助
