有机肥和秸秆还田对黄泥田土壤微食物网的影响

Effects of manure fertilizer application and straw return on micro-food web of yellow field soil

有机质的数量和性质决定了土壤微食物网结构和功能。施用有机肥和秸秆还田是低产黄泥田的主要培肥措施,为研究这2种不同性质有机质对低产黄泥田土壤生物肥力的影响,该文比较了等碳量施用有机肥和秸秆还田对土壤微生物、原生动物和线虫群落结构的影响,并以线虫区系分析为工具,比较这2种有机质对土壤微食物网结构和功能的影响。试验设对照(不施肥,CK)、化肥(NPK)、化肥+有机肥(NPKM)、化肥+秸秆还田(NPKS)4个处理。2 a短期试验结果表明:与NPK处理相比,NPKM处理提高了细菌通道(细菌、原生动物、食细菌线虫)、真菌通道(真菌、食真菌线虫)、植物通道(植物寄生线虫)生物类群丰度,NPKS处理也促进了大部分生物类群丰度,但提升效果低于NPKM处理。施肥(NPK、NPKM、NPKS)降低了线虫群落成熟度指数、结构指数,提高了基础指数,但彼此差异不显著,且各施肥处理均在线虫区系剖面第二象限,表明各施肥处理对土壤微食物网的干扰程度较低。各施肥处理中细菌足迹、植物足迹远高于真菌足迹,表明施肥带来的碳主要通过细菌通道和植物通道进入土壤微食物网。总之,与秸秆还田相比,施用有机肥对土壤微食物网群落结构的影响更大,但两者对土壤微食物网功能的影响差异不显著。该结果可为黄泥田土壤微食物网结构研究提供参考。

Yellow calyed soil,as a typical low-yield paddy soil,is widely distributed in southern China.Manure application and straw return were the most two important measures for improving soil fertility.Previous studies had been reported the effects of manure application and straw return on rice yield,soil physico-chemical characteristics and enzymes,but seldom on soil biological fertility.The aim of this study was to compare the effects of pig manure and rice straws on the community of microorganism,protozoa,nematode as well as the structure and functions of soil micro-food web,the assemblage of microorganism,protozoa and nematode,via nematode fauna analysis.Compare to crop straws,manure was labile organic matter and had low carbon nitrogen ration.Since the quantity and quality of organic matter determined the structure and function of soil micro-food web,it was hypothesised that the effects of manure on the structure and functions of soil micro-food web were more stronger.The experiment conducted at a double-rice cropping field in Jinmen City of Hubei Province,China,and included 4 treatments of without fertilizers(Control),mineral fertilizers(NPK),mineral fertilizers combined with organic manure(NPKM)and mineral fertilizers combined with straw incorporation(NPKS),and the organic carbon content from NPKM and NPKS treatments were equal.Soil sampling was done after late rice harvest(19 November 2012 and 22 October 2013).Analysis of soil microbial communities was done by phospholipid fatty acids(PLFAs)composition,protozoa were classified into 3 functional groups of flagellate,ciliate and amoebae,and nematode were identified into genus level and classified into 4 functional groups of bacterial-feeding nematode,fungal-feeding nematode,plant-parasitic nematode and omnivorous-predatory nematodes.The nematode ecological indices of maturity index(MI),structure index(SI),enrichment index(EI),basal index(BI),bacterial footprint,fungal footprint and herbivore footprint,were used to evaluate structure and functions of soil micro-food web.The combination of SI and EI used to infer the condition of soil micro-food web.The results showed that NPKM increased the abundance of functional groups within bacterial decomposition channel(bacteria,protozoa,bacterial-feeding nematodes),fungal decomposition channel(fungi,fungal-feeding nematode)and plant channel(plant-parasite nematodes)in comparison with those of NPK treatment,and the improvement level was higher in the NPKM treatment than in the NPKS treatment although NPKS also improved the abundance of most functional groups.Fertilization treatments(NPK,NPKM,NPKS),no significant differences in between,decreased the value of MI and SI and increased the BI compared to Control,indicating that fertilization increased the resilience and decreased the complexity of soil micro-food web.The nematode fauna profile of the fertilization treatments(NPK,NPKM,NPKS)and control located at the second quadrant,which inferred that the disturbance resulted from short-term fertilization was relative low,and the soil micro-food web in each treatment was structured.The values of bacterial footprint and herbivore footprint in all treatments were much higher than that of fungal footprint,which indicated that the carbon from fertilization enter the soil micro-food web mainly pass through bacterial and plant channel.The changes of bacterial footprint were not consistent between two sampling times indicated that the effects of short-term fertilization on fast decomposition pathway were not stable.In conclusion,the effects of NPKM on the structure of soil micro-food web were stronger than NPKS,however,their influence on the functions of soil micro-food were similar under short-term fertilization.