长期施用不同无机肥对旱地红壤线虫群落的影响

红壤生态系统中土壤生物群落对于维持土壤功能的正常发挥具有重要作用.本研究基于持续25年的红壤旱地化肥定位试验,研究不同无机肥组合,包括氮磷钾(NPK)、氮磷钾补充石膏(NPKCaS)、氮磷(NP)、氮钾(NK)和磷钾(PK)对花生生长季土壤线虫群落的影响.结果表明： 土壤线虫总数、营养类群以及各生态指数在处理间差异显著(P<0.01).线虫总数由高到低的顺序为PK>NPKCaS>NPK>NP>NK.除5月外,NPK、NP、NK处理的线虫总数均显著低于NPKCaS和PK处理.NPKCaS处理的优势类群为食细菌线虫,平均丰度为42.1%,其他处理均以植食性线虫为优势营养类群,其平均丰度为38%~65%.NPKCaS处理线虫群落较高的成熟度指数、瓦斯乐斯卡指数和结构指数说明土壤食物网结构较为成熟和稳定,同时表明氮磷钾补充石膏通过缓解土壤酸化创建了良好的土壤健康状况.仅施氮钾的处理则相反.本研究证实了施用石膏和磷肥是改善红壤质量的有效措施,土壤线虫群落分析能较好地反映不同无机肥对红壤旱地生态系统的影响.

Responses of soil nematode communities to long-term application of inorganic fertilizers in upland red soil.

Soil biota plays a key role in ecosystem functioning of red soil. Based on the long-term inorganic fertilization field experiment (25-year) in an upland red soil, the impacts of different inorganic fertilization managements, including NPK (nitrogen, phosphorus and potassium fertilizers), NPKCaS (NPK plus gypsum fertilizers), NP (nitrogen and phosphorus fertilizers), NK (nitrogen and potassium fertilizers) and PK (phosphorus and potassium fertilizers), on the assemblage of soil nematodes during the growing period of peanut were investigated. Significant differences among the treatments were observed for total nematode abundance, trophic groups and ecological indices (P<0.01). The total nematode abundance decreased in the order of PK > NPKCaS > NPK > NP > NK. The total number of nematodes was significantly higher in NPKCaS and PK than in NPK, NP and NK except in May. Plant parasitic nematodes were the dominant trophic group in all treatments excepted in NPKCaS, and their proportion ranged between 38% and 65%. The dominant trophic group in NPKCaS was bacterivores and represented 42.1%. Furthermore, the higher values of maturity index, Wasilewska index and structure index in NPKCaS indicated that the combined application of NPK and gypsum could remarkably relieve soil acidification, resulting in a more mature and stable soil food web structure. While, that of the NK had the opposite effect. In conclusion, our study suggested that the application of both gypsum and phosphate is an effective practice to improve soil quality. Moreover, the analysis of nematode assemblage is relevant to reflect the impact of different inorganic fertilizer on the red soil ecosystem.