Assessment of the Effect of Hydrolysed Starch Graft Copolymers Application on Soil Nutrient (Phosphorus and Nitrogen) Retention

The effects of the application of the graft copolymers (Hydrolyzed starch-g-polyacrylonitrile (HSPAN) and Hydrolyzed starch-g-polyacrylic acid (HSPAA)) on the nitrogen (N) and phosphorus (P) retention capacity of soil was evaluated in this study. Soil nutrient (N and P) retention capacity tests was carried out at three graft copolymers application rates (3.0, 6.0, and 9.0g/kg soil) against a blank soil sample to which graft copolymers was not applied. Diammonium phosphate (DAP) at 0, 100, and 200mg in aqueous solution/kg soil were applied in triplicates. The soil samples were mixed thoroughly and allowed to air-dry. The residual N and P contents of the soil samples were determined and reported as the amounts of nutrients retained as a function of the graft copolymer and DAP application rates. The result of this study has clearly demonstrated the potential of the graft copolymers to alleviate problems related to nutrient loss from the soil media. Leaching of nutrients (N and P) in soil has been found to be reduced to minimal (0.46%N, and 1.13%P) with the application of hydrolyzed graft copolymer and the nutrients are thus available to plant for growth by suction pressure difference.