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

ABSTRACT 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.摘要 巴西农村地区的基础卫生设施难以满足当地卫生需求。为此，巴西农牧业研究公司（Embrapa）研发了一套分散式厌氧处理系统，用于生活污水处理。处理后污水（Treated Sewage Effluent，TSE）可完全替代玉米种植所需矿质肥料中的氮素，而玉米是巴西小农户种植的典型饲料作物。因此，本研究旨在探究以TSE作为肥料时玉米的生长响应。本试验于2018-2019年夏季生育期在巴西圣保罗州圣卡洛斯市的砂质壤土中开展，供试品种为粮饲兼用型杂交玉米。试验采用随机区组设计，设置三次重复，共评估4种不同养分来源的施肥处理：1. NPK组：以尿素、过磷酸钙、氯化钾作为养分来源；2. EfPK组：以TSE作为氮源，辅以矿质肥料提供磷钾养分；3. Ef组：仅施用TSE；4. PK组：仅施用矿质肥料提供磷钾养分。试验通过短闭端沟灌方式施用TSE。基于污水的养分浓度数据，TSE可作为玉米种植的氮素及其他养分来源。通过水肥一体化分期施用TSE，可使玉米的产量性状接近仅施用矿质肥料的NPK处理组。对于巴西小农户典型的小规模玉米种植而言，该污水回用技术具备可行性。