Corn crop responds positively to fertigation with black water from sewage treated by decentralized anaerobic system

The basic sanitation systems are not enough to meet the sanitary requirements in the rural areas of Brazil. Hence, a decentralized anaerobic system was developed by Embrapa to enable the treatment of domestic sewage. The treated sewage effluent (TSE) should be applied to completely replace the N from mineral fertilizer required by corn plants, a typical crop cultivated by Brazilian smallholder farmings for animal feed. Hence, the purpose of this study was to investigate the corn crop responses to the use of TSE as fertilizer. A field experiment was carried out in a sandy clay loam soil at São Carlos, state of São Paulo, Brazil, over 2018-2019 summer growing season of a hybrid corn cultivar with dual aptitude (grain and silage production). Four treatments about application of different nutrient sources were evaluated in a randomized block design with three replications: 1-NPK: urea, simple superphosphate and potassium chloride as nutrient sources; 2-EfPK: TSE as N source + PK from mineral fertilizers; 3-Ef: TSE only; 4-PK: mineral fertilizers only. TSE was applied to crop by short and closed-end furrow irrigation. TSE can be used as a source of nitrogen mainly and other nutrients for corn crop nutrition based on the knowledge of effluent nutrient concentrations. TSE split application through fertirrigation can lead to corn yield parameters close to those from NPK application using only mineral fertilizers as nutrient sources. The reuse of this wastewater is feasible for small-scale corn production which is typical of Brazilian smallholder farming.