Phosphorus (P) is one of the essential macronutrients for plant growth, being a highly required resource to improve the productive performance of several crops, especially in highly weathered soils. However, a large part of the nutrients applied in the form of fertilizers becomes “inert” in the medium term and cannot be assimilated by plants. Rationalizing the use of phosphorus is a matter of extreme importance for environmental sustainability and socioeconomic development. Therefore, alternatives to the management of this nutrient are needed, and the use of P-solubilizing microorganisms is an option to optimize its use by crops, allowing the exploration of less available fractions of the nutrient in soils and reducing the demand for phosphate fertilizers. The objective of this study is to discuss the importance of phosphorus and how microorganisms can intermediate its sustainable use in agriculture. In this review study, we present several studies about the role of microorganisms as phosphorus mobilizers in the soil. We describe the importance of the nutrient for the plants and the main problems related to the unsustainable exploitation of its natural reserves and the use of chemical fertilizers. Mainly we highlight how microorganisms constitute a fundamental resource for the release of the inert portion of the nutrient, where we describe several mechanisms of solubilization and mineralization. We also discussed the benefits that the inoculation of P-solubilizing microorganisms provides to crops as well as practices of using them as bioinoculants. The use of microorganisms as inoculants is a viable resource for the future of sustainable agriculture, mainly because its application can significantly reduce the application of P and, consequently, reduce the exploitation of phosphorus and its reserves. In addition, new research must be conducted for the development of new technologies, prospecting new biological products, and improvement of management practices that allow for higher efficiency in the use of phosphorus in agriculture.

Based on the concepts of circular economy and bioeconomy, the reuse of agrifood residues through vermicomposting can help solve serious environmental problems such as soil contamination and degradation, erosion and climate change. In this sense, the objective was to identify, quantify and analyze the physical, chemical, hormonal, amino acid content and microbial biodiversity of three formulations of vermicompost, with and without inoculation of microorganisms from native forest and commercial formulation, aiming at the production of an organic fertilizer rich in microorganisms for use in sustainable production systems. As a result, the vermicompost formulations presented values higher than the minimum requirements stipulated by Brazilian legislation for the registration of class A composite organic fertilizer. There is a significant difference between the vermicomposts, in the parameters related to the content of phosphorus, auxin, tryptophan and organic matter, as well as the relation between humic and fulvic acids. Bacillus sp. and Trichoderma sp. were also influenced by the type of vermicompost formulation. In addition, inoculation with microorganisms from native forest promoted an increase in biodiversity, in which the presence of Actinomyces sp. and Azotobacter chrooccocum contribute to the reduction in the levels of heavy metals in the compost. It is concluded that vermicomposting is a potential tool in the reuse of agri-food residues, with expressive microbial diversity that can influence plant growth, suppression of pathogens, minimize or reduce the effects of biotic and abiotic stresses on plant production, in addition to contributing to maintenance of soil biodiversity, integral fertility and resilience to climate change.

Organic wastes are considered the most significant components of urban solid waste, negatively affecting the environment. It is essential to use renewable resources to minimize environmental risks. Composting is one of the most sustainable methods for managing organic waste and involves transforming organic matter into a stable and nutrient-enriched biofertilizer, through the succession of microbial populations into a stabilized product. This work aimed to evaluate the efficiency of the new type of composter and the microbial and physiochemical dynamics during composting aiming to accelerate the degradation of organic waste and produce high-quality compost. Two inoculants were evaluated: (1) efficient microorganisms (EM); (2) commercial inoculum (CI), which were compared to a control treatment, without inoculation. Composting was performed by mixing organic waste from gardening with residues from the University's Restaurant (C/N ratio 30:1). The composting process was carried out in a 1 m³ composter with controlled temperature and aeration. The thermophilic phase for all treatments was reached on the second day. Mature compost was obtained after an average of 120 days, and composting in all treatments showed an increase in the availability of P and micronutrients. The new composter helped to accelerate the decomposition of residues, through the maintenance of adequate oxygen content and temperature control inside the cells, providing high metabolic activity of microorganisms, contributing to an increase in physicochemical characteristics, also reducing the composting time in both treatments. During composting, the bacteria and actinobacteria populations were higher than yeasts and filamentous fungi. The inoculated treatments presented advantages showing more significant mineralization of P-available and micronutrients such as Mn and Zn in terms of the quality of the final product in comparison to the control treatment. Finally, the new composter and the addition of inoculants contributed significantly to the efficiency of the process of composting organic waste.