Dynamics of soil organic matter and carbon balance in palm and sorghum consortium irrigated with reuse water in the semi arid Northeastern

Abstract

The methodologies for reusing sewage for agricultural purposes are innovative in the country, which still lacks incentives and public policies in the sector, particularly in the semiarid region. The consolidation of such methodologies will strongly impact the management of water resources, sanitation, and the environment, making more water available for irrigation, protecting water bodies from contamination, and mitigating greenhouse gas emissions. The organic matter in sewage is relevant as an organic fertilizer, constituting an alternative to traditional mineral fertilizer, with a high impact on the attenuation of soil and water contamination processes. Therefore, the objectives of this research will be: i) Evaluate the dynamics of the SOM (at the compartment level) after the use of wastewater, providing information necessary for the creation of a protocol for characterization and use of the organic matter present in the effluent; ii) Characterize potentially toxic elements from the sewage effluent and from the soil (after reuse); iii) Calculate the soil C balance in sorghum + palm consortium cropping systems in the semiarid region of Pernambuco, aiming at mitigating greenhouse gas emissions. The investigation activities will be conducted at the Mutuca reuse unit in Pesqueira-PE. The experiment will be in randomized blocks with four replications, being a 3x2 factorial arrangement, with three irrigation depths, 80%, 100%, and 120% of sorghum ETc and absence and presence of mulch (8 ton ha-1).Additionally, studies and analyzes will be carried out with the support of the laboratories of UFRPE (Headquarters and UAST) and Embrapa Instrumentação (National Laboratory of Agro-Photonics - LANAF, São Paulo). This research is in line with the Sustainable Development Goal - SDG 6 (drinking water and sanitation) and UNESCO SDG 17, as well as with State priority technology areas, specifical technologies for quality of life (sanitation; water security), technologies for production (agriculture), and technologies for sustainable development (pollution treatment, environmental preservation). The use of these production systems based on species of regional appeal will bring relevant subsidies for reuse actions, as well as for regionalization. Furthermore, understanding the dynamics of organic matter (at the level of compartments), the C balance, and the toxic potential of the effluent in the soil after reuse brings necessary information for the creation of a protocol for the characterization and use of the organic matter present in the effluent is of paramount importance. To provide elements and bases for socio-economic-environmental analysis of the reuse of treated sewage in the semiarid region. (AU)