Impact of Herbicide-Based Conservation Tillage on Soil Macro Fauna Abundance and Distribution in Western Uganda

Abstract

Weed management is an important aspect in conservation agriculture. Weeds reduce crop yields and can lead to total crop failure if not controlled. Manual weed control is labour intensive and therefore limits the production area. In many rural African communities, it has become increasingly difficult to hire labour for weeding and other farming activities, due to dwindling labour. Thus, farmers have resorted to the use of herbicides to control weeds despite the limited knowledge of their effects. The aim of this study was to assess the impact of herbicide based conservation tillage on soil macro fauna in Western Uganda. A household survey was conducted in Rugando and Ndaijya Sub-Counties inRwampara district. A semistructured questionnaire was administered on 65 randomly selected households. This was followed by a field experiment to determine the impact of herbicide based conservation tillage. Three treatments of 40m by 20m fields that are ten days after application (T1), sixty days after application (T2) and as the control no herbicide applied (T3) were used in a completely randomised block design with two blocks of bananas and coffee plantation. Sampling was done randomly along the transect in each experimental plot using quadrants measuring 65cm by 65cm and 25cm by 25cm were. Four sampling points and a total of 24 samples were collected along the transect for each treatment plot. At each sampling point, soil monoliths were excavated up to 30cm depth and termites, earthworms, millipedes and centipedes were sorted out with in the soil layers. The study revealed that herbicide based conservation tillage is the most practiced in the area and this has greatly benefited farmers. It also found that soil macro fauna abundance and distribution were significantly affected by the herbicides (p<0.05). The abundance of earthworms, millipedes, centipedes and termites was found to be significantly lower in soil that had been sprayed with glyphosate herbicide 10 days back with lower soil macro faunal distributions in the first soil layer compared to the second soil layer. Therefore, there is need to reduce herbicide use, look at more ecologically friendly measures and carry out more studies on its effect on soil fauna with time and on field crops.