title: Reclaimed wastewater: impact on soil-plant system under tropical conditions.
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 NH(4)(+), Ca(2+), Mg(2+), K(+), SO(4)(2-), Cl(-), H(3)BO(3), Mn(2+) and Zn(2+), 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.
authors: Research Center for Geochemistry and Geophysics of Lithosphere, University of São Paulo, Avenida Pádua Dias, 11, 13418-900, Piracicaba, São Paulo, Brazil. brunoffp2000@yahoo.com.br
authors: B F F
authors: BF
authors: Pereira
authors: Z L
authors: ZL
authors: He
authors: M S
authors: MS
authors: Silva
authors: U
authors: U
authors: Herpin
authors: S F
authors: SF
authors: Nogueira
authors: C R
authors: CR
authors: Montes
authors: A J
authors: AJ
authors: Melfi