Abstract: Spent sulfite liquor(SSL) from bagasse pulping was modified by graft copolymerization of acrylic acid(AA) and/or acrylamide(AM) onto lignosulfonate.Effects of SSL and different modified products upon sandy soil structure were studied.At the application rate of 0.2%, the dry contents of stable aggregates(>0.25 mm, COAs) in sandy soil samples treated with AA and AM modified products were 49.4% and 48.9%, and wet COAs were 38.1% and 39.9%, respectively.Among the products modified with both monomers, the product with AA/AM ratio of 20/80 had the best performance on improving structure of sandy soil.The acting mechanisms of polymer on soils were reviewed.It was suggested that, at dry status the bonding of anionic groups onto sand grains was stronger than that of non-ionic groups, and there might be adhesion between polymers and sandy soils.

Key words: spent sulfite liquor, graft copolymerization, soil improvement, combating desertification