Effect of gypsum and polyacrylamides on water turbidity and infiltration in a sodic soil

Water ponded on sodie soils can develop turbidity problems which seriously affect rice crop establishment. A total of 19 polyacrylamide products were assessed for their effectiveness to control water turbidity in a sodic soil under laboratory conditions. Anionic polyacrylamides were more effective than cationic or non-ionic polyacrylamides. When combined with gypsum, polyacrylamides were found to be more effective than when applied alone. A split application strategy was more efficient than continuous application of polyacrylamide treatments. Different rates of polyacrylamides at 2.5, 5, and 10 kg/ha did not show significant difference in controlling water turbidity. Selected polyacrylamides were also tested on soil columns to study their effect on infiltration and percolation of water through the soil. Results showed that polyacrylamides combined with low rates of gypsum did not modify the infiltration pattern to a greater extent. This study demonstrated that anionic polyacrylamides applied with small quantities of gypsum through a split application strategy would be an appropriate technique to overcome water turbidity problems in sodic soils. Additional keywords: sodicity, nephelometric turbidity units, rice establishment.
Introduction It has been observed that sodic soils in rice-growing areas create turbid water, and that this seriously affects the successful establishment of rice seedlings (Humphreys and Barrs 1998). Similar [...]