The Influence of Soil Aggregate Stabilizers on the Biological Activity of Soils

Abstract

AbstractThe influence of three synthetic polyelectrolytes, hydrolyzed polyacrylonitrile (HPAN), modified vinyl acetate maleic acid compound (VAMA), and a new polymer 212 on the biological activity in six agricultural Arizona soils and quartz sand was investigated. Particular attention was directed to (a) the rate and extent that these materials decompose, (b) the possible toxic or inhibitory effect that these materials may exert on the soil microflora, and (c) the effect that these materials have on the rate and extent of decomposition of a crop residue such as oat straw.VAMA was found to stimulate biological activity in soil as evidenced by the total cumulative CO2 evolved during 14 days of incubation with soil. HPAN and polymer 212 had little effect on the over‐all biological activity of well‐aerated soil cultures during this period of incubation. This situation appeared to be the same regardless of the presence or absence of oat straw.The rate of evolution of CO2 measured during intervals of 24 hours, indicated that in soil (a) a certain small portion of VAMA and a very small portion of HPAN and polymer 212 is immediately available to attack by the soil microflora, and (b) when this supply is exhausted the remaining material is so slowly available it has no measurable influence on the cumulative CO2 evolved over a period of five months by the method employed.The presence of VAMA in sand delayed peak CO2‐evolution depending on the rate of application. This indicated that the soil conditioner had a temporary toxic or inhibitory effect on the microflora in the sand cultures.