Due to the lack of information on the application of commercial organic fertilizers versus manure or composting in the growing of lettuce and their influence on biological attributes of the environment, the present study was carried out to verify the effect of different management systems of velvet beans and the use of manure and solid organic composting on the diversity and microbial biomass of soil. The treatments consisted of the management of velvet beans, incorporated or not into the soil, and the application of bovine manure, composting, commercial organic fertilizer and a control treatment without fertilization. The soil attributes were evaluated at the following times: at the time of the velvet bean management, and at 15, 55 and 105 days after this process. The management and solid organic fertilizer treatments had no significant effect on the microbial biomass and bacterial population. For fungi, the incorporation of velvet bean was more efficient, allied to the use of commercial organic fertilizer. The incorporation of velvet bean and the treatment with composting were favorable for the grown of mycorrhizal fungi. Treatment with composting, followed by the incorporation of velvet beans, and the control treatment provided the higher population of saprophytic nematodes, while the incorporation of velvet bean into the soil increased the population of plant parasitic nematodes.
Organic agriculture; velvet bean; microbial biomass