also been found to be toxic in low concentrations to many strains of pseudomonas, a maj or

heterotrophic bacteria commonly found in forest soils (Boldt and Jacobsen, 1998). This mortality

was attributed to the acetolactate synthase inhibition (ALS) property of sulfometuron methyl

(Whitcomb, 1999). This finding might explain the reduction in microbial biomass found in our

experiment from applying sulfometuron methyl.

 The chemical properties of hexazinone and sulfometuron methyl limited the treatment

effects on this coastal wet pine flat when flooding and the associated high water tables were

present. Nitrification was impacted more than ammonification by excessive water from flooding.

This condition might explain why the sulfometuron methyl-hexazinone treatment had a

significant difference with the control in the nitrification data, but not the net nitrogen

mineralization or ammonification data. The effect of soil moisture content on herbicides was

observed when comparing the ammonification treatment data with the nitrification results

(Figure 5-3; Figure 5-5; Figure 5-6). The results show microbial biomass measurements are able

to detect differences between sites where herbicides have and have not been applied. These Cmb

measurements were also sensitive to the number of herbicide applications used on a given site.

Fungal biomass carbon did not detect any differences among the treatments. Previous studies

have failed to detect any herbicide effects on fungal communities (Busse et al. 2004).

 A primary reason for the fungal biomass measurements failing to detect statistically

significant differences between the treatments may be attributed to the time since the treatments

were applied. Most of the individual effects of herbicides on microbial biomass levels are greatly

reduced beyond two years after application (Li et al. 2003). With the exception of the Pt.

Washington nitrogen studies, the soils were collected and analyzed for fungal and microbial

biomass 40 months after the second year treatments. The predictions were generally good except