长期施肥对渭北旱塬麦田土壤线虫群落特征的影响

为探究长期定位施肥对黄土高原渭北旱塬麦田土壤线虫群落的影响，以长武国家黄土高原农业生态试验站的长期定位试验（1984—2018年）为平台，调查裸地（L）以及不施肥（CK）、施氮磷肥（NP）、单施有机肥（M）、氮磷肥配施有机肥（MNP）的小麦田土壤线虫群落数量、组成结构和生态功能指数，并分析其与土壤理化性质的关系。结果表明：（1）小麦田土壤线虫数量显著高于裸地，而CK、M和MNP处理使小麦田中土壤线虫数量比NP处理提高了31.63%~56.20%；（2）施肥减缓了长期种植小麦导致的食细菌线虫（特别是头叶属）相对丰度的下降，单施有机肥的处理（M）植食性线虫相对丰度显著降低，同时，相比于CK，施用有机肥的M和MNP处理杂食/捕食线虫相对丰度分别增加了18.4%和8.24%，表明有机肥对杂食/捕食线虫的促进作用；（3）长期施肥处理土壤线虫Shannon多样性指数（H）和指示土壤健康状况的瓦斯乐卡指数（WI）分别为1.80~2.19和0.36~0.68，相较于裸地（H=2.36；WI=1.57）有所下降，但M和MNP处理的线虫成熟度指数（MI）和结构指数（SI）均高于其他处理（L、CK和NP处理），表明施用有机肥有助于土壤食物网维持复杂的结构和成熟稳定的状态；（4）不同施肥措施下土壤全氮、有机碳、微生物生物量碳和氮以及可溶性碳的变化是影响土壤线虫数量和群落特征的重要环境因素。

Effects of long|term fertilization on soil nematode community of wheat field in Weibei dryland, China

To explore the effects of long|term fertilization on the characteristics of soil nematode communities of wheat field in Weibei dryland, a long|term positioning experiment (1984-2018) of the National Agricultural Ecological Experimental Station in Changwu County, Shaanxi Province was conducted.Different fertilization treatments, including bare land (L), as well as wheat fields without fertilizer (CK), nitrogen and phosphorus fertilizers (NP), organic fertilizer (M), nitrogen and phosphorus combined with organic fertilizer (MNP) were set up to investigate the abundance, composition, structure and ecological indices of soil nematode communities in farmlands. The relationships of nematode communities with soil physicochemical properties were also analyzed. The results showed that: (1) Soil nematode abundance in wheat fields were significantly higher than that of bare land. CK, M and MNP treatments increased the abundance of soil nematodes by 31.63%~56.20%, compared with NP treatment. (2) Fertilizer treatments mitigated the decrease in the relative abundance of bacterial|feeding nematodes (i.e.Cephalobus). The relative abundance of herbivorous nematodes decreased significantly in the treatment of organic fertilizer (M)treatment. At the same time, the relative abundance of omnivorous/predatory nematodes in M and MNP treatments increased by 18.4% and 8.24%, compared with CK, indicating the promotional effect of organic fertilizer on omnivorous/predatory nematodes. (3) Under long|term fertilization, soil nematode Shannon diversity index (H) and Wasilewska index (WI) were 1.80~2.19 and 0.36~0.68, respectively, which were lower than those in bare land (H=2.36; WI=1.57). However, compared with other treatments (L, CK and NP), M and MNP treatments obviously increased the maturity index (MI) and structure index (SI) of nematode community, indicating that organic fertilizer application helped maintain the structure complexity and stability of soil food web. (4) Changes in soil total nitrogen, organic carbon, microbial biomass carbon and nitrogen and dissolved organic carbon under different fertilization treatments were important environmental factors affecting soil nematode abundance and community pattern.