长期施肥对砂姜黑土可溶性碳淋溶的影响

Effects of long-term fertilization on dissolved carbon leaching in lime concretion black soils

研究施肥对砂姜黑土可溶性碳淋溶的影响,对有机肥的可持续利用有重要意义。该研究依托33 a的长期试验,分析常规施肥(MF)、化肥+低量小麦秸秆(MFL)、化肥+高量小麦秸秆(MFH)、化肥+猪粪(MFP)和化肥+牛粪(MFC)等施肥方式对土壤剖面(0~60 cm)理化性质、微生物性状、可溶性有机碳(Dissolved Organic Carbon,DOC)和可溶性无机碳(Dissolved Inorganic Carbon,DIC)含量与分布的影响,探寻可持续的有机肥利用方式。结果表明,长期增施有机肥后0~60 cm剖面各土层有机碳、微生物量碳、氮均有不同程度提升,而对土壤全氮、容重和pH值的影响主要发生在0~20 cm表层。与MF处理相比,增施有机肥后0~20和>20~40 cm土层DOC含量均有显著(P <0.05)提高,而对>40~60 cm土层无显著影响。相对而言,0~60 cm各土层DIC的含量均有显著提升。长期增施有机肥后0~60 cm各土层DOC的UV280吸收值和芳香性指数分别较MF处理均有显著提高,其中以MFC处理最为显著,0~20、>20~40和>40~60 cm土层DOC的芳香性指数分别提高71.2%、153.3%和38.1%,这说明长期增施有机肥后土壤剖面DOC结构发生明显改变,芳香化合物含量提高,化合物结构变得更加复杂。逐步线性回归模型表明,土壤剖面DOC和DIC分布主要受pH值和微生物量碳的共同影响,且pH值的影响强度大于微生物量碳,而土壤剖面DOC化学结构受微生物量碳的影响。总体而言,外源有机物料投入的类型和数量是影响土壤剖面可溶性碳分布的重要措施,长期增施农家肥的碳淋失风险高于秸秆还田。

It is necessary to generate a sustainable strategy for evaluation of carbon leaching risk and organic fertilizer application by studying the effects of different fertilization practices on dissolved carbon leaching along soil profile in the area of lime concretion black soils. Aiming to analyze the contents and distribution of physicochemical, microbial properties,dissolved organic carbon(DOC), and dissolved inorganic carbon(DIC) contents in soil profile based on a 33-year long-term fertilization experiment to select an environmentally friendly organic amendments, five treatments were designed, including mineral fertilization(MF), mineral fertilization combined with low amount wheat straw(MFL), mineral fertilization combined with high amount wheat straw(MFH), mineral fertilization combined with pig manure(MFP), and mineral fertilization combined with cattle manure(MFC), respectively. Results showed that the contents of soil organic carbon, microbial biomass carbon(MBC), and microbial biomass nitrogen(MBN) in the profile at 0-60 cm soil depth were substantiality increased,whereas the values of soil total nitrogen, bulk density and pH value were mainly influenced at 0-20 cm soil depth in the organic amendments treatments compared with MF treatment. Compared with the MF treatment, soil DOC contents at 0-20 cm and >20-40 cm soil depths under long-term organic amendments application treatments were significantly(P<0.05) increased,whereas the values were not significantly increased at >40-60 cm soil depths. In contrast, soil DIC contents under long-term organic amendments application treatments at 0-60 cm depth were significantly(P<0.05) increased compared with the MF treatment. Both the values of UV280 absorption and aromaticity index(AI) at 0-60 cm soil depth were significantly(P<0.05)increased under long-term organic amendments application treatments, especially for the MFC treatment. The values of AI at the 0-20, >20-40, and >40-60 cm soil depths under the MFC treatment were significantly increased by 71.2%, 153.3%, and 38.1%, respectively. It was indicated that soil DOC chemical structure in the whole profile at 0-60 cm soil depth under long-term organic amendments application was greatly influenced and the contents of aromatic compound were increased,which suggested that soil DOC chemical structure under long-term organic amendments application were more complex.Furthermore, stepwise lineal regression showed that the DOC and DIC contents in the profile at 0-60 cm soil depth were regulated by soil p H value and MBC, and the strength of influence soil p H value was larger than soil MBC. Soil DOC chemical structure in the soil profile were mainly influenced by soil MBC. Generally, the type and amount of exogenous organic amendments were the two major factors influencing the characteristics of soil dissolved carbon distribution. The risk of dissolved carbon leaching was aggravated after long-term organic amendments application, especially for pig and cattle manure. Crop straw application is a recommended organic agricultural practice deceasing dissolved carbon leaching risk.