WATER-SAVING BY IRRIGATING TWO VARIETIES OF SORGHUM (ENERGY PLANT) WITH TREATED MUNICIPAL WASTEWATER: A 3-YEARS STUDY IN CENTRAL GREECE
In the last few years, the problem of limited precipitations and, consequently, the lack of water along with the rapid climatic changes have been one of the main topics of discussion in environmental forums all over the world. On the other hand, as the world population increases, so does water consumption for civil and agricultural use and urban wastewater. Under these circumstances, the national scientific communities focus their research on the possibility of reusing treated urban wastewater in agriculture as a source of irrigation water. The effects of treated urban wastewater, by using subsurface drip irrigation (S.D.I.), on yield and growth of two varieties of sorghum, sweet and fiber, used as an energy plant, were studied, as well as the freshwater saving. For this purpose, experiments were made at the Experimental Farm Station of the University of Thessaly in the Velestino area during the years 2005 and 2006 (sweet sorghum) and 2008 (fiber sorghum) that consisted of a fully randomized complete block design with two treatments in four replications. The first treatment was irrigated with freshwater (FW 100ET), whereas the second one was irrigated once with wastewater and twice with freshwater (WW 100ET), in sequence. The results showed that the rate of growth (height of plants) and the final yield of dry biomass differed but not significantly (P<0.05) in both treatments during the three years of study. However, by using processed urban wastewater, a significant saving in fresh irrigation water was achieved. Irrigating sorghum with treated wastewater seems to be a quite promising method to produce energy from biomass.