长期施肥对棕壤有机碳储量及固碳速率的影响

利用棕壤肥料长期定位试验,研究了不同施肥条件下棕壤有机碳在0~60 cm土层的含量和储量特征以及土壤固碳速率.试验共设6个处理,即氮磷肥有机肥配施(M_2NP)、氮肥有机肥配施(M_2N)、单施有机肥(M_2)、单施氮肥(N)、氮磷肥配施(NP)和不施肥处理(CK).结果表明:经过31年长期不同施肥,各处理土壤有机碳(SOC)含量和储量的剖面分布均呈现随土层深度增加而显著降低的规律.本试验条件下M_2NP、M_2N、M_2、NP、N、CK处理的耕层有机碳富集系数分别为0.465、0.455、0.407、0.48_2、0.393、0.471,表明耕层土壤对有机碳的保持强度最强.在0~60 cm土层土壤有机碳储量表现为M_2NP、M_2NM_2、NPNCK,有机肥和化肥配施能够显著提高土壤有机碳含量和储量.与试验前相比,CK处理各土层土壤有机碳含量和储量均显著降低.各处理碳库管理指数(CPMI)表现为M_2NPM_2NM_2NNPCK.分析不同施肥处理土壤固碳速率可知,与试验前相比,CK处理表现为碳的净释放,固碳速率达-401.4 kg·hm~(-_2)·a~(-1);固碳速率最高的为M_2NP,M_2N,分别达到489kg·hm~(-_2)·a~(-1)、440._2 kg·hm~(-_2)·a~(-1).综合结果表明,化肥、有机肥配施所产生交互效应更有利于棕壤有机碳储量的增加及固碳速率的提高.

Effect of long-term fertilization on total organic carbon storage and carbon sequestration rate in a brown soil

A long-term fertilizer located experiment was performed to quantify the relative change of soil organic carbon (SOC) content, storage, and sequestration rate in 0~60 cm layer of a brown soil under six fertilization modes (inorganic nitrogen fertilization, N; inorganic nitrogen and phosphorus fertilization, NP; inorganic nitrogen, phosphorus, and organic fertilization, M₂NP; inorganic nitrogen, and organic fertilization, M₂N; organic fertilization, M₂; and no fertilization, CK). The results revealed that after 31 years, SOC content and storage were declined significantly with the increase of depth. The SOC accumulation coefficient of topsoil under the six fertilization modes (M₂NP, M₂N, M₂, NP, N, and CK) was 0.465, 0.455, 0.407, 0.482, 0.393, and 0.471, respectively. The SOC storage of different treatments in 0~60 cm soil layer followed the order of M₂NP > M₂N > M₂ > N > NP > CK. In the conditions of this study, inorganic combined with organic fertilization was the best way to significantly increase SOC content and storage. In comparison with the soil before the trial, SOC content and storage of CK declined sharply in all soil layers. Similarly, the carbon pool of management index (CPMI) also followed the order of M₂NP > M₂N > M₂ > N > NP > CK. The results of SOC sequestration rate showed that there was a net carbon release in CK treatment. The carbon sequestration rate of CK reached -401.4 kg·hm^-2·a^-1. However, M₂NP and M₂N treatments reached the highest rate of carbon sequestration, 489 kg·hm^-2·a^-1 and 440.2 kg·hm^-2·a^-1, respectively. Comprehensive results showed that the interactive effect of organic and inorganic fertilization was more conductive to improving SOC storage and sequestration rate.