Journal of Pure and Applied MicrobiologyVol. 8 No. 2

Response of Soil Microbial Communities to the Selective Herbicides: A Microcosm Approach

Aabid Hussain Lone*, K.P. Raverkar, Navneet Pareek and Ramesh Chandra

Department of Soil Science, G.B. Pant University of Agriculture and Technology, Pantnagar U. S. Nagar Uttarakhand - 263 145, India.

Received on 13 July 2013 and accepted on 28 August 2013

 

ABSTRACT

The impact of six different herbicides representing several chemical families on soil microbial community was investigated using laboratory microcosm approach. The herbicides consisted of isoproturon, metribuzin, clodinafop propargyl, atlantis (mesosulfuron methyl + idosulfuron methyl sodium) and sulfosulfuron applied at normal agricultural rates. The sixth herbicide namely UPH-110 (Clodinafop propargyl 12% + Metribuzin 42% WG) was tested at four different application rates. The impact was assessed on various soil biological health indicators viz, microbial biomass carbon, soil respiration, dehydrogenase and phosphatase activities. The response of microbial community was mixed. Overall among the various methodological approaches adopted, dehydrogenase activity was most sensitive and microbial biomass carbon the least under the existing conditions. Interestingly, the sensitivity of acid phosphatase towards the applied herbicides was more than alkaline phosphatase. Influence whether positive or negative was however only transitory except UPH-110 @ 1000 g ha-1 in case of soil respiration. The influence of UPH-110 was dose dependent. Significant toxic impact was mostly observed at higher concentrations (600 and 1000 g ha-1). The magnitude of hazard and duration of toxicity increased as the dose increased.

Keywords : Herbicide, Microbial biomass carbon, Microbial activity, Phosphatase activity, Soil Respiration, Dehydrogenase activity.