Incorporação de lodos de estações de tratamento de água: efeitos sobre atributos do solo e desempenho agronômico de cultivos anuais

Abstract

Water treatment residuals (WTRs) are generated in large quantities during the water purification process for human consumption. On this way, many alternatives of WTRs final destination have been proposed such as agricultural use. However, regarding the WTRs application in cultivated soils, it is essential to set the dose and the most suitable strategy of preparation as well as the possibility of combination with other materials as sewage sludge (SS) in order to provide benefits for crops. In this context, the present study aimed to verify the influence of increasing doses of WTRs with corrected pH and soil incorporated on the development of mayze and ryegrass, on physical-hydric soil attributes, on nutritional composition and accumulation of inorganic contaminants in soil and in plant tissue, determining the potential use of WTRs pH corrected as soil amendments, as well as to compare the soil incorporation of WTRs with corrected pH with others ways of preparing WTRs and with the combination of WTR and SS, being these treatments set out by the dose of 30 tons ha-1 . The experiment was carried out at the “Estação Experimental Terras Baixas” of “Embrapa Clima Temperado”, being installed in field conditions in a randomized blocks design with four replicates and with the following treatments: Increasing doses (0, 15, 30 e 60 tons ha-1 dry mass) of solarized and ground WTRs with corrected pH, in addition to four treatments with solarized and ground WTR with non-corrected pH (30 tons ha-1 ); non-solarized WTR with corrected pH (30 tons ha-1 ); commercial soil amendment MecPlant based on bio-stabilized pine bark (30 tons ha-1 ) and mix of solarized and ground WTR with corrected pH, with solarized and ground sewage sludge (30 tons ha-1 ) in proportion of 75:25 of dry mass (LA:LE), respectively. It was concluded that: the increasing doses of WTR do not affect the agronomic variables, while the treatment LA:LE increases the height and dry mass of cultivated plants; the WTR increasing doses do not change the attributes related to soil fertility, not decreasing the available phosphorus content and not increasing the percentage of CTC occupied by aluminum; the treatment LA:LE increases the content of P, Cu and Zn and, consequently, increases the content of these elements in plant tissue; the increasing doses of WTRs until the maximum of 60 tons ha-1 as well as the mix of WTR and SS do not interfere on heavy metal content in soil and in tissue of ryegrass; the soil physical-hydric variables are not influenced by increasing doses of WTRs within the tested; the WTRs with corrected pH, without pH correction and the non-solarized and nonground WTR as well as the mix LA:LE did not modify the analyzed soil physical variables.