The objective of this work was to evaluate the influence of different doses of spent coffee grounds on soil microorganisms responsible for nutrient cycling and the development of corn crop under no-tillage. The trial was conducted in a field at the State Center for Agricultural Professional Education Fernando Costa, in a randomized block with 4 treatments, with increasing doses, 0, 3, 6 and 9 t ha-1 of coffee grounds. Microbial biomass carbon (CBM), baseline respiration (RBS), microbial and metabolic quotient (qMIC and qCO2), plant development (corn) and productivity were evaluated. At the dose of 9 t ha-1 of spent coffee grounds, there was an increase in organic matter and microbial biomass (219.01) and qMIC (1.5). With increased microbial activity, the development of the plant was 20% higher compared to the control, plant height (2.21) and stem diameter (2.99). Consequently, the productivity was 42 bags ha-1 higher than the control. Thus, we can conclude that spent coffee grounds can be a viable alternative for use as organic fertilizer in agriculture.

Technologies that use rhizobacteria to promote plant growth are increasing in agriculture, results have shown improvements in soil quality, increases in productivity, and decreases in the use of synthetic inputs, The objective of work was to characterize bacterial isolates regarding their biological activity and growth promotion of soybean plants grown in a controlled environment. Fifteen bacteria were isolated from soils with continuous use of biological fertilizer. They were evaluated for enzymes production (amylase and protease), nitrogen fixation, antagonistic activity to phytopathogenic fungi, and indoleacetic acid (IAA) production, Soybean seeds were inoculated with bacterial isolates in a greenhouse and evaluated for plant development and soil chemical attributes. The results showed that 8 of the 15 isolates presented production of amylase, protease, or both and 4 isolates presented nitrogen-fixing capacity. The percentage of isolates with high or moderate inhibitory action against the fungi Sclerotinia sclerotiorum, Macrophomina phaseolina, and Fusarium solani were 73.3%, 66.6%, and 73.3%, respectively. The IAA production varied from 8.56 to 31.33 µg mL-1 (5 isolates had low, 6 had moderate, and 4 had high production). The soybean development was significantly higher in 80% of the treatments with inoculation with bacterial isolates. Five bacterial isolates effectively present all characteristics for use as inoculant (biofertilizer) to promote the development of soybean plants.

Plant growth-promoting rhizobacteria (PGPR) inhabit the rhizosphere of several cultivated plants. Bacteria of the genus Bacillus have great functional importance in plant development. The objective of this research was to evaluate different doses of Bacillus sp. in the development of soybean and corn crops and in the chemical and microbiological attributes of the soil. The essays were conducted in the field in the 2016/2017 harvest. The soybean and corn seeds were treated with two doses of Bacillus sp. at a concentration of 109 CFU ml-1, with 10 and 20 ml of 100 kg of seed used in soybeans and 80 and 100 ml of 100 kg of seed in corn. The experiments were completely randomized in block with four repetitions. Chemical and microbiological attributes and plant development were evaluated. The results showed that the microbial activity was achieved at the dose of 20 ml of Bacillus sp. and positively influenced the weight of the grains and soybean productivity. In corn crops, the dose of 80 ml of Bacillus sp. showed better performance on chemical and microbiological attributes, resulting in increased shoot and root mass, and a significant increase in productivity. From the results obtained, it can be concluded that the use of Bacillus sp. it is a viable alternative for sustainable agriculture, and the dose of 20 ml and 80 ml of 100 kg of soybean and corn seeds, respectively, presented better results in microbial activity and in the development of plants.

Beans are one of the most important foods for the majority of the world's population, and Brazil is the third largest producer. This production can be affected by pests and diseases, such as gray stem rot, caused by the fungus Macrophomina phaseolina, which is difficult to control due to the low efficiency of chemical products. One of the viable alternatives is the use of microorganisms and/or secondary metabolites to control the pathogen and promote plant growth. The objective of this work was to test the antagonistic action of the filtrate of cave bacteria against M. phaseolina and promote the growth of common bean. To determine the period of infection of the phytopathogen, a severity test was carried out, and subsequently the filtrate of cave bacteria, identified as IS22, was applied at different times of inoculation of the phytopathogen in the bean plant BRS Esteio. Plant height, fresh and dry weight of shoots, root length, fresh and dry weight of roots were evaluated. The fungus did not manifest symptoms in the plant, but in relation to the growth promotion of the common bean, the filtrate provided a significant increase in the analyzed variables from the V3 stage. It is concluded that the tested filtrate is a promising biostimulant for the market.