Fig. 4. Interactive effect of water treatment residual amendment rate and incubation time at 10% rate by weight on reducing known As species concentrations in water treatment residuals–amended poultry litter samples incubated at 23°C (top) and 35°C (bottom). Data are expressed as the mean of two replicates ±1 SD. DMA, dimethylarsinic acid; MMA, monomethylarsonic acid; ROX, roxarsone.