Persistence of Selected Pesticides used in Sugarcane Production in Soil and Water in the Northern Lake Victoria Catchment

Abstract

Pesticide use in the Lake Victoria catchment area ofUganda has continuously been increasing in the last ten years due to increase in the production of horticultural export crops and sugarcane. The farms have to use pesticides for increased crop productivity in order to meet market demands. This study was conducted to monitor pesticide levels in soils and runoff water following treatment of a sugarcane field in the Northern Lake Victoria watershed. Soil and water samples were collected over a period of 304 days after planting of the sugarcane and analysed for pesticide residues. In soils, glyphosate levels ranged from 0.8-135.5 μglkg. Ametryn ranged from 44.9-1705.4 μg/kg, and Dichlorophenoxy acetic acid (2.4-D) 15.6- 835.2 μg/kg. In water, glyphosate levels ranged from l.3 to 42.2 upstream and 0.4 to 9.3 downstream, ametryn ranged from < 15 to 31.5 μgll upstream and from <1 5- 18.6 g/1 downstream and, 2.4-D<LO to 15.7 μg/1 upstream and <10 to 13.4 μg/1 downstream. The quality of water obtained was compared with the Canadian Environmental Quality thresholds for fresh water, irrigation and livestock water for selected pesticides. At the applied rates the use of herbicides Touch down ( 48% glyphosate trimesium) and Gesapax-H (21% ametryn and 29%, 2,4-D) for the control of weeds in sugarcane farming system at Kakira was found to be within acceptable levels.

Keywords: Pesticides, soil, water, pollution, concentration.