Assessing the Effects of Solarization and Sodium Azide Amendments on Selected Soil Parameters, Enzyme Activities and Microbial Populations
- 1 Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, USA
- 2 George Washington Carver Agriculture Experiment Station, College of Agriculture, Environment and Nutrition Sciences, Tuskegee University, Tuskegee, USA
- 3 Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, USA
Abstract
Soil borne pathogens result in serious losses in yield of crops grown in the United States (US) and various parts of the world. One of the most effective chemicals used to control these pathogens was methyl bromide (CH 3 Br, MeBr), a pre-plant fumigant with a broad spectrum of activity. Sodium azide has been proposed in combination with solarization as a viable alternative to replace MeBr due to environmental concerns with respect to ozone depletion in the stratosphere and as a possible carcinogen. However, the possible impacts of sodium azide as a soil pollutant and its effect on soil biological processes have not been fully studied. In this study the effect of sodium azide used alone and in combination with solarization and mulching on selected soil enzyme activities (phosphomonoesterases, arylsulfatase and phosphodiesterase) were assessed. Responses of arylsulfatase and phosphodiesterase to solarization and mulching and azide treatment were found to be affected in the same way, suggesting a similar mode of action. Soil pH in control soils was significantly increased by azide application; however, in mulched soils, pH was decreased. The significant decrease in soil pH in mulched soils may be very important in explaining the increase in the acid phosphatase activity observed in mulched soils. Overall, solarization and sodium azide treatment significantly reduced both fungi and bacterial populations but the responses among the various treatments varied significantly.
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