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.