Industrial waste ferrogypsum — a substitute for gypsum to alleviate sodicity

Ferrogypsum is a waste from the effluent treatment plant of the titanium industry located in Tuticorin in south India. It contains gypsum (526.3 g/kg) and iron (102.4 g/kg as Fe2O3). It does not contain any heavy metal at a detectable level. To evaluate ferrogypsum as a soil amendment to alleviate sodicity, a field experiment was conducted on a sodic soil (fine mixed non-calcareous isohyperthermic very deep Vertic Ustropepts) with rice as the test crop. There were 7 treatments consisting of ferrogypsum as well as gypsum used either alone or in combination with farmyard manure or green manure, and a control. The grain and straw yields of rice were significantly increased over the control. Postharvest soil analysis revealed a significant reduction in pH (9.00 to 7.63) and ESP (37 to 14.9) due to soil reclamation with ferrogypsum or gypsum. Thus, ferrogypsum was as effective as gypsum in alleviating sodicity.