施肥方式对土壤活性有机碳及碳库管理指数的影响

基于长期田间定位试验,采用田间采样与数理统计法研究不同施肥方式对紫色土活性有机碳及碳库管理指数(CPMI)的影响。施肥方式包括不施肥(CK)、单施氮肥(N)、化学氮磷钾肥配施(NPK)、单施有机肥(OM)、有机肥配施化学氮磷钾肥(OMNPK)和秸秆还田配施化学氮磷钾肥(RSDNPK)。结果显示,施肥的各处理均能够提高土壤有机碳及其活性组分含量,以OM和RSDNPK处理的提升效果最佳。相比CK,OM处理的土壤总有机碳(TOC)、易氧化有机碳(PXOC)、微生物量碳(MBC)、溶解性有机碳(DOC)含量分别提高91.4%、109.2%、57.5%、35.1%,RSDNPK处理的TOC、PXOC、MBC、DOC含量分别提高142.8%、95.4%、70.8%、46.2%。土壤PXOC、MBC、DOC占TOC的比例(分配比例)分别为36.18%~49.13%、1.64%~2.58%、0.57%~0.94%,其中,PXOC和MBC的分配比例在RSDNPK处理中较CK显著(P<0.05)降低,而DOC的分配比例在各处理间无显著差异。OM和RSDNPK处理的CPMI显著(P<0.05)高于N和NPK处理。土壤PXOC、MBC含量与氮磷养分之间,以及CMPI与MBC、PXOC、TN、AN、AP均呈现显著(P<0.05)或极显著(P<0.01)正相关性。研究结果说明,有机肥或秸秆还田配施氮磷钾化肥能够提高耕层土壤有机碳储量,改善土壤质量,PXOC与CPMI可用作表征土壤质量变化的敏感指标。

Effects of fertilization on soil active organic carbon and carbon pool management index

Based on long-term field experiment, the effects of different fertilization treatments on purple soil active organic carbon and carbon pool management index (CPMI) were investigated. Six fertilization treatments were used in this study, including no fertilizer (CK), only synthetic N fertilizer (N), synthetic NPK fertilizer (NPK), only organic manure (OM), organic manure with synthetic NPK (OMNPK), crop residues with synthetic NPK (RSDNPK). The results showed that all treatments with fertilizers increased the content of soil organic carbon and active organic carbon compared with CK, and OM and RSDNPK showed the highest enhancement. The content of soil total organic carbon (TOC), permanganate oxidized organic carbon (PXOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC) were increased by 91.4%, 109.2%, 57.5%, 35.1%, respectively, in OM, and by 142.8%, 95.4%, 70.8%, 46.2%, respectively, in RSDNPK. PXOC, MBC and DOC accounted for 36.18%-49.13%, 1.64%-2.58% and 0.57%-0.94% of TOC, respectively. The proportions of PXOC and MBC were significantly (P<0.05) decreased in RSDNPK compared to those in CK, but the proportion of DOC had no significant change within all treatments. CPMI of OM and RSDNPK were significantly (P<0.05) higher than those of N and NPK treatments. The content of PXOC, MBC were significantly (P<0.05 or P<0.01) positively correlated with the content of N, P nutrient, and CPMI were significantly (P<0.05 or P<0.01) positively correlated with the content of PXOC, MBC, TN, AN and AP. It was concluded that application of organic manure or crop residues with synthetic NPK fertilizer could increase the organic carbon storage and improve soil quality. PXOC and CPMI could be used as sensitive indicators of purple soil quality.