Assessment of the Effect of Hydrolysed Starch Graft CopolymersApplication 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.

Keywords: Graft copolymers; starch; soil; nutrient retention;