长期不同施肥下新疆灰漠土有机碳储量演变分析

新疆灰漠土耕地面积176万hm²,为新疆农业的发展起关键支撑作用。本研究基于新疆灰漠土农田肥力长期监测试验,选择其中不施肥、施化肥和化肥配施有机肥、秸秆的六个处理,对不同施肥处理下土壤表层（0~20cm）和亚表层（20~40cm）土壤碳储量变化特征进行了研究。结果表明：长期不施肥或施用化肥、有机肥均能提高灰漠土表层和亚表层土壤有机碳储量,其中表层土壤有机碳储量提高（4.0~43.7）tC/hm²;亚表层土壤有机碳储量提高（9.0~49.5）tC/hm²。采用不同施肥措施,土壤有机碳储量累积存在时段差异,不施肥耗竭种植条件下在试验初始5年碳储量缓慢下降,但在其后的18年中逐渐升高,因此在肥力水平较低土壤上,即使不施肥但长期耕作也将提高土壤碳储量,有利于贫瘠土壤固碳。这一结果也表明,若采用短期试验观测的数据不能全面反映人为管理措施对土壤碳储量的长期影响,对于碳储量的研究适宜依托长期观测试验的平台来完成。与不施肥或长期施用化肥相比,采用有机无机配施使灰漠土有机碳碳储量提高了32.1%~152.7%,固碳效应显著。将分层土壤容重考虑在内的等质量土壤碳储量计算方法能够较为客观评估秸秆还田的固碳效应。

Evolution analysis of soil organic carbon sequestration under long-term different fertilization of grey desert soil in Xinjiang

With a cropping area of 1.76 million hectares, grey desert soil（hapliccalcisol）is crucial for agricultural development in Xinjiang in northwest China. The objective of our experiment was to study the effect of different fertilization on carbon sequestration based on a long-term experiment station of grey desert soil. There were six treatments：no fertilization,chemical fertilization,chemical fertilization plus manure and chemical fertilization plus straw returned to the soil（CK,NP,NPK,NPKM,hNPKM,NPKS）. The characteristics of soil organic carbon （SOC）sequestration in surface（0~20cm）and subsurface（20~40cm）layers of desert soil were studied from 1989-2011. We found that the SOC stock was improved under all treatments including no fertilizer,chemical fertilizer,and manure fertilizer plots. The SOC stock was elevated by（4.0~43.7）tC/hm² in the surface layer and（9.0~49.5）tC/hm² in the subsurface layer. The SOC stock differed across time periods among plots. The SOC stock decreased during the first 5 years and increased slightly during the latter 18 years in the no fertilizer plot. This indicates that the SOC can be sequestrated in relative low fertility soil even with no fertilizer application in arable land. This result also implies that the effect of management on SOC stock can be illustrated based on long term experimentation. SOC stock under the manure plot was increased by 32.1%~152.7% compared with the no fertilizer and chemical only plots. Take into consideration of the layered soil bulk density and quality of soil carbon reserves calculation method can evaluate the carbon sequestration of straw returned objectively.