SORGHUM RESPONSE TO SALINE INDUSTRIAL COOLING WATER APPLIED AT 3 GROWTH-STAGES

Saline wastewater from industrial or agricultural sources may be an al ternative irrigation supply in mid regions if effective crop and water management strategies for their use are developed. A field experiment was conducted to determine if grain yields of sorghum [Sorghum bicolo r (L.) Moench] irrigated with undiluted saline wastewater from cooling towers of an electrical power generation plant can be significantly i ncreased by applying nonsaline water at a critical growth stage. The w astewater had an average electrical conductivity (EC) of 0.67 S m(-1) and was high in CaSO4. Plot studies were conducted for 4 yr using conv entional cultural practices and sprinkler irrigation on Tujunga loamy sand-sanford fine sandy loam soil (mixed, thermic Typic Xeropsamment-c oarse-loamy, mixed, nonacid, thermic Typic Xerorthent). Highest grain yields were obtained from the nonsaline control plots and from treatme nts that received nonsaline water during either the vegetative or repr oductive growth stages. Plant height decreased in response to salinity , and differences between treatments were apparent by 27 d after plant ing. Plant height and grain yield were both negatively correlated with soil salinity by the 3rd yr of the experiment. Over an extended lengt h of time, the best treatment for maximizing yield and utilizing salin e wastewater is the application of nonsaline water early in the season to germinate and establish seedlings, followed by saline water during the grain-filling stage.