Sorghum growth in soil treated with sewage sludge from the textile industry

Sewage sludge (SS), a residue from wastewater treatment can be a hazard to the environment because it may contain trace elements and other toxic substances. But it is also rich in organic matter and plant nutrients so that an attractive destination for the residue is its use in agriculture as fertilizer and soil conditioner. The aim of this work was to evaluate the effect of doses of SS from the textile industry on sorghum plant growth. The experiment was carried out under greenhouse conditions using typic Haplorthox soil occurring at Jaboticabal, SP, Brazil. The experiment design was totally randomized with 7 treatments (absolute control, without fertilization and SS, mineral control, with mineral fertilization based on soil analysis, 7, 14, 21, 28 and 35 t ha-1 SS, dry basis) in 3 replications and sorghum as the test plant. At the end of the plant cycle, plant dry matter and grain production were estimated, and soil samples were analyzed for soil chemical fertility. Textile sewage sludge improved soil fertility, except in relation to K and Mg, plant dry matter and grain production. It also caused symptoms of K deficiency and other symptoms of unknown origin. The SS rates caused the same grain production and the highest doses caused delay in the panicle emission