Effects of the Compound Microbial Fertilizers on Eucalyptus Growth and Soil Microecology

In order to realize the reduction of chemical fertilizer and provide new fertilizer for ecological forest management, and improve the soil acidification of Eucalyptus forest land, the experiments were carried out in the sprouting forest and the newly-planted forest at the same time, the compound microbial fertilizer 1 (N∶P₂O₅∶K₂O=14∶6∶12, effective viable bacteria count of Paenibacillus in October frozen sample of Bacillus subtilis≥2.0 CFU·g^-1, hereinafter referred to as ″Fertilizer 1″), the compound microbial fertilizer 2 (N∶P₂O₅∶K₂O=14∶4∶8, effective viable bacteria count of Paenibacillus in October frozen sample of Bacillus subtilis≥2.0 CFU·g^-1, hereinafter referred to as ″Fertilizer 2″) and the conventional chemical fertilizer were applied respectively to compare the differences of Eucalyptus growth and soil microecology under the three fertilizer treatments. The results showed that Fertilizer 1 and Fertilizer 2 had better growth promotion and forest land improvement effects on Eucalyptus than the conventional fertilizers, and the amount of converted NPK was reduced by 15.8% and 31.6%, respectively. Compared with the conventional chemical fertilizer, Fertilizer 2 had better growth-promoting effect on the sprout forest after 24 months of fertilization, and the diameter at breast height and plant height increased by 11.2% and 7.5%, respectively. The growth-promoting effect of Fertilizer 1 on the newly-planted forest was better, and the diameter at breast height and plant height increased by 13.8% and 10.5%, respectively. The compound microbial fertilizer could promote the degradation of soil organic matter into humic substance, increase the number of microbial flora, improve the soil nutrients, and significantly alleviate the soil acidification. It could be concluded that the compound microbial fertilizer could replace chemical fertilizer for planting the Eucalyptus plantation, which had the effect of reducing weight and increasing efficiency and also improving the soil fertility.