益生菌肥料在桉树人工林可持续发展中的应用

Application of PGPB Fertilizer in Green Development to Enhance the Sustainability of Eucalypt Plantations

为促进林木生长,减少化学肥料使用,保护环境,维护地力,本研究从林木根际分离植物益生菌,经系统试验,筛选出一批对桉树生长具有明显促进作用的优良菌株。其中的DU07菌株兼具固氮、解磷、解钾功能,被研制成菌剂、有机菌肥、益生菌复合肥。菌剂接种桉树苗木的育苗和造林试验覆盖广西桉树大部分栽培区。在广西高峰林场建立的146.2 hm2示范林,18月龄林木平均树高达11.16 m,胸径7.38 cm,均分别高于对照,起到了良好的示范作用。不含无机氮素的有机菌肥在试验初期的肥效较慢,但半年后,菌肥处理的林木胸径、树高均超过对照,其肥效显示长效缓释作用;施用菌肥的桉树根区土壤微生物、尤其是固氮菌数量明显增多,土壤酶活性均有不同程度的提高。无机有机益生菌复合肥总养分≥15%,比总养分≥30.0%的对照肥减少一半,然而1.5年生试验林的树高和胸径均分别高于对照,土壤的速效氮、磷、钾也均高于对照。表明益生菌肥有利于土壤中各种物质的分解和转化,在改善土壤状况和维护地力上具独特作用。这对于在生产中减少无机化肥的使用,保护土壤环境具有重要的现实意义。

For promoting tree growth, decreasing chemical fertilizer application, protecting the environment and maintaining soil fertility, a study was conducted to isolate PGPB （Plant growth promoting bacteria） from the tree rhizosphere and examine potential benefits of these when used in eucalypt plantation silviculture. Some selected strains, which are known for their distinct ability to promote tree growth, were screen out and used to prepare a PGPB solution, PGPB organic fertilizer, PGPB organic and inorganic complex fertilizer. The PGPB preparation was used to inoculate 1.3 M Eucalyptus seedlings from 2012.10 to 2014.3; at 18 months after planting the plantations of these seedlings had an average height of 11.2 m and average DBH of 7.8 cm. The results from the fertilizer application trials showed that PGPB organic fertilizer, which had some inorganic additives, resulted in slower early growth than that of the standard chemical （inorganic） fertilizer （the control - CK）. But from 6 till 36 months, all PGPB fertilizer treated trees had greater average height and DBH than the control treatment. Also, the number of soil microbes, especially azotobacter, was found to be much higher in the soil around PGPB fertilizer treated trees than in the soil around the trees in control treatment, as was soil enzyme activity and azote contention. The PGPB organic and inorganic complex fertilizer only contained 15% inorganic nutrient control treatment compared to 30% inorganic nutrient content in the control fertilizer （CK）, but average tree height and DBH of PGPB organic and inorganic fertilized trees exceeded that of the control, and at age 1.5 years trees averaged 12.2 m and 9.0 cm respectively. The results showed that PGPB fertilizer enhanced tree growth, decreased chemical fertilizer requirements whilst helping to protect the environment, maintain soil fertility and enhance the sustainability of eucalypt plantations.