Soil organic carbon (SOC) content and its fractions are critical indicators of soil quality and function. The impacts of the addition of exogenous organic fertilizer on SOC and its fractions in black soil with high SOC remains unclear. Based on a experiment with five years treatments in the Hailun Agro-ecological Experimental Station of the Chinese Academy of Sciences, we explored the effects of equal amount of chicken manure (30 t·hm-2·a-1) on SOC content and physical fractions (free light fraction carbon fLFC, occluded light fraction carbon oLFC, heavy fraction carbon HFC) and chemical fractions (easily oxidized organic carbon EOC, dissolved organic carbon DOC, humic acid carbon HAC, fulvic acid carbon FAC, humin carbon HMC) in 0-50 cm soil profile. There were three different methods of surface coverage (CM), shallow incorporation 15 cm (ST) and deep incorporation 35 cm (DT). The results showed that the SOC content of CM, ST, and DT was increased by 0 to 19.2%, 1.7% to 15.0% and 2.1% to 22.4%, respectively. The SOC storage was increased by 3.4%, 5.7% and 9.1%, respectively. The SOC content and storage of each treatment decreased with the deepening of soil layer. The organic carbon conversion rate of DT treatment was significantly higher than that of ST and CM. Compared with CK, CM treatment increased fLFC, oLFC and HFC by 39.5%, 30.0% and 17.6% in 0-10 cm soil layer, and the chemical fractions DOC and HAC were increased by 100.0% and 30.7%, respectively. The contents of fLFC, oLFC and HFC in 10-20 cm soil layer in ST treatment were significantly increased by 45.5%, 22.2%, and 10.8%, respectively, compared with CK, while the contents of DOC and HMC in 20-30 cm soil layer were increased by 95.2% and 19.5%, respectively. In the 20-50 cm soil layer, fLFC, oLFC and HFC increased by 16.7%-29.2%, 15.4%-46.2% and 12.0%-20.8%, and EOC, DOC, HAC and FAC increased by 12.0%-18.0%, 119.1%-129.4%, 37.1%-43.8% and 9.7%-13.3%, respectively. In general, chicken manure deep mixed returning (35 cm) was the most effective measure to improve the organic carbon storage and active carbon component content of black soil soil profile, and the influence depth can be below 40 cm soil layer, which would provide a theoretical basis for the improvement of cultivated land fertility and the optimization of carbon sequestration technology in black soil area in Northeast China.
土壤有机碳(SOC)含量及其组分可表征土壤质量及功能,高SOC的黑土增添外源有机肥对土壤剖面SOC及其组分的影响尚不明确。本研究于2019年在中国科学院海伦农业生态试验站开展连续5年田间定位试验,以传统耕作(CK)为对照,研究等量鸡粪(30 t·hm-2·a-1)通过覆盖(CM)、浅混15 cm(ST)和深混35 cm(DT)3种方式对0～50 cm土壤剖面SOC含量及其物理组分(游离态轻组碳fLFC、闭蓄态轻组碳oLFC、重组碳HFC)和化学组分(易氧化有机碳EOC、溶解性有机碳DOC、胡敏酸碳HAC、富里酸碳FAC、胡敏素碳HMC)的影响。结果表明: 在0～50 cm土壤剖面,与CK相比,CM、ST和DT处理SOC含量分别增加0～19.2%、1.7%～15.0%和2.1%～22.4%,SOC储量分别增加3.4%、5.7%和9.1%,各处理SOC含量和储量均随土层加深呈降低趋势。DT处理有机碳转化率显著高于ST和CM处理。与CK相比,CM处理在0～10 cm土层物理组分fLFC、oLFC和HFC含量分别提升39.5%、30.0%和17.6%;化学组分DOC和HAC含量分别提升100%和30.7%。ST处理在10～20 cm土层fLFC、oLFC和HFC含量较CK分别显著增加了45.5%、22.2%和10.8%,在20～30 cm土层DOC和HMC含量分别增加了95.2%和19.5%。DT处理在20～50 cm土层fLFC、oLFC和HFC含量分别增加了16.7%～29.2%、15.4%～46.2%和12.0%～20.8%,EOC、DOC、HAC和FAC含量分别增加了12.0%～18.0%、119.1%～129.4%、37.1%～43.8%和9.7%～13.3%。总体上,鸡粪深混还田(35 cm)是提升黑土土壤剖面有机碳储量及活性碳组分含量的最有效措施,且影响深度可到40 cm土层以下,可为东北黑土区耕地地力提升与固碳技术优化提供理论依据。.
Keywords: black soil; chicken manure; organic carbon fractions; soil organic carbon.