Affiliations: [a] Environmental Studies Division, National Aquatic Resource Research & Development Agency, Crow Island, Colombo-15, Sri Lanka | [b] Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi, 400-8511, Japan
Abstract: To understand pesticide loading from farmlands, evaluation of farmers’ perceptions and land use patterns of pesticide loading from the upper catena of the tropical tributary river study was conducted using Rapid Rural Appraisal (RRA), which utilized semi-structured questionnaire surveys and key personnel interviews to collect data from the farmers in the Upper Kotmale Sub-Watershed (UKSW). The results recorded 46 commercial brands of pesticide and 25 active ingredients from the sub-watershed. Cluster analysis showed four utilized insecticides (i.e. diazinon, deltamethrin, sulfur, and chlorpyrifos), four fungicides (i.e. mancozeb, propineb, metiram, and chlorothalonil), and two weedicides (mainly metribuzin); the analysis was based on the usage of the active ingredient per acre. Selection of vegetable crops and cultivation seasons greatly impacted pesticide applications based on farmers’ perceptions. Toxic concentrations of chlorpyrifos and deltamethrin were observed in water, which exceeded the acute toxicity level for aquatic life (even with 1% of the pesticide load [scenario 4]). These chemicals drain into rivers from the pesticides remaining after the total pesticide usage in the sub-watershed. Therefore, farmers’ perceptions on pesticide applications are highly correlated to pesticide applications and toxicity levels in river waters.
Keywords: Farmers’ perceptions, land use, pesticide, sub-watershed, toxicity
