Interactions Between a Polyacrylamide and a Polysaccharide as Soil Conditioners When Applied Simultaneously

We grew tomato seedlings in two different soils with a polyacrylamide and a polysaccharide applied singly and together at two different application rates. In one soils maximum response was obtained at 125 kg ha-1 for the polyacrylamide with no additional response from the polysaccharide. At a lower rate the two polymers gave additive response. In the second soil, which was less responsive, especially to the polysaccharide, the combined effects were close to additive. Some benefit was obtained from using acid to help bring the polysaccharide into solution. In another test, maximum response was obtained for the lowest level of combined polyacrylamide and polysaccharide, equivalent to 31.2 and 6.2 kg ha-1, respectively.