长期施肥下黄壤有机碳库演变及固存特征

Evolution and Sequestration Characteristics of Organic Carbon Pool in Yellow Soil under Long-term Fertilization

【目的】了解农田土壤有机碳库的演变及其特征,对于提升和维持土壤质量、增加作物产量和减缓温室效应具有重要意义。【方法】依托贵阳黄壤肥力与肥效长期定位试验,分析长期(21 a)不同施肥处理下黄壤碳库容量变化、源汇关系、产量效应及黄壤碳库提升和维持的方法。【结果】(1)施有机肥处理土壤有机碳含量较化肥处理明显提升,且年增加速率明显高于化肥处理;(2)施有机肥处理有机碳储量显著高于施化肥处理,有机肥各处理比CK高13%~19%;(3)长期施肥条件下土壤有机碳储量变化与累积碳投入量呈显著渐进相关性,在目前较高的有机碳投入水平下,土壤有机碳的固持已接近饱和;(4)21 a黄壤累积碳投入量分界拐点值为54.29 t/hm2,当小于此值时,土壤固碳效率较高,为26.62%;当累积碳投入量大于此值时,固碳效率仅1.72%;(5)黄壤累积碳投入量与玉米产量亦有极显著相关性,但随着碳投入量的增加,产量增加明显变缓;(6)为避免有机碳库容提前达到饱和,增加资源浪费和环境污染风险,1/4M+3/4NPK施肥方案较合理。【结论】有机肥与化肥配施对黄壤有机碳含量、有机碳密度和固碳速率等提升有显著作用,但生产实践中,有机肥施用量不可过高,要因地制宜,找到适宜作物增产、土壤培肥和土壤碳库容量保持稳定变化的节点是农田生态系统固碳的核心。

【Objective】The study aimed to understand evolution and carbon sequestration characteristics of organic carbon pool in farmland soil for promoting and maintaining soil quality,increasing crops yield and reducing the greenhouse effect.【Method】The carbon pool storage variation,source and pool relationship,yield efficiency in yellow soil of different treatments under the long-term fertilization（21 a） and the increase and maintenance method of carbon pool in yellow soil were analyzed based on the long-term located experiment of yellow soil fertility and fertilizer efficiency.【Result】（i） The soil organic carbon content of the applying organic manure treatment is higher than the applying chemical fertilizer treatment significantly and the annual increase rate of the applying organic manure treatment is higher than the applying chemical fertilizer treatment.（ii） The organic carbon storage of the applying organic manure treatment is higher than the applying chemical fertilizer treatment significantly and the soil organic carbon storage of different applying organic manure treatments is 13 %-19 % higher than CK.（iii） There is a significant gradual correlation between soil organic carbon storage variation and accumulation carbon input under the long-term fertilization and the soil organic carbon sequestration is close to a saturation level at the current higher organic carbon input level.（iv） The boundary infection value of accumulation carbon input in yellow soil under the long-term fertilization（21 a） is 54.29 t/hm2.The soil carbon sequestration efficiency is high when the boundary infection value of accumulation carbon input is less than 54.29 t/hm2 and the soil carbon sequestration efficiency is 1.72 % only when the boundary infection value of accumulation carbon input is higher than 54.29 t/hm2.（v） There is a very significant correlation between soil accumulation carbon input and maize yield but the yield increase becomes very slow with increase of carbon input.（vi） The 1/4 M ＋ 3/4 NPK application schedule should be used to avoid the saturation of organic carbon reservoir in advance and reduce resources waste and environmental pollution risk.【Conclusion】The organic manure and chemical fertilizer combination application has a significant promoting effect on organic carbon content,organic carbon density and carbon sequestration rate in yellow soil but the organic manure application amount should be adjusted according to the nodal point（the core of carbon sequestration in the farmland ecosystem） of rational yield increase,soil fertility improvement and stable variation of soil carbon reservoir in production practice.