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Reclaimed wastewater: impact on soil-plant system under tropical conditions |
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| Authors: | Pereira B F F He Z L Silva M S Herpin U Nogueira S F Montes C R Melfi A J |
| Affiliation: | a Research Center for Geochemistry and Geophysics of the Lithosphere, University of São Paulo, Avenida Pádua Dias, 11, 13418-900, Piracicaba, São Paulo, Brazil b Indian River Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, 2199 South Rock Road, Fort Pierce, FL 34945, USA c Department of Hydraulic Engineering and Sanitation, University of São Paulo, Avenida Trabalhador Sãocarlense, 400, 13566-590, P.O. Box 359, São Carlos, São Paulo, Brazil d Embrapa Satellite Monitoring. Avenida Soldado Passarinho, 303,13070-115, Campinas, São Paulo, Brazil e Center for Nuclear Energy in Agriculture, University of São Paulo, Avenida Centenário, 303, 13416-903, Piracicaba, São Paulo, Brazil f Department of Soil Science, University of São Paulo, Avenida Pádua Dias, 11, 13418-900, Piracicaba, São Paulo, Brazil |
| Abstract: | This study investigated the ionic speciation of reclaimed urban wastewater (RWW), and the impact of increasing RWW irrigation rates on soil properties and plant nutrition under field conditions. Most RWW elements (>66%) are readily available as NH4+, Ca2+, Mg2+, K+, SO42−, Cl−, H3BO3, Mn2+ and Zn2+, but in imbalanced proportion for plant nutrition. Lead, Cd, Cr and Al in RWW are mostly bounded with DOM or OH−..Irrigation with RWW decreased soil acidity, which is beneficial to the acidic tropical soil. Although RWW irrigation builds exchangeable Na+ up, the excessive Na+ was leached out of the soil profile after a rainy summer season (>400 mm). Benefits of the disposal of RWW to the soil under tropical conditions were discussed, however, the over irrigation with RWW (>100% of crop evapotranspiration) led to a nutritional imbalance, accumulating S and leading to a plant deficiency of P and K. |
| Keywords: | Urban effluent Wastewater disposal Water reuse Ionic speciation Al toxicity Acidic soil |
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