Abstract:
The combustion of coal during thermal electricity generation produces huge
volumes of fly ash solid waste. The disposal and storage of dry fly ash in the
environment have resulted in high nutrient concentration levels becoming toxic
to humans, air, soil and water environments. Soil nutrient deficiency is limiting
sustainable food productivity with soil nutrient deficiencies and limited access to
fertilizers or biological options aggravating the predicament of hunger. This
study focused on assessing the environmental impacts of fly ash and its potential
utilisation in crop production. The study was conducted at Harare Power Station
(170 50‘ S and 310 1‘ E) and Harare Experimental Station (170 49‘S and 31o2‘ E).
Mixed research methods were used. To unearth the environmental impacts of fly
ash qualitative research approach guided by the interpretivism paradigm was
applied. Purposive sampling of six key informants was implemented and data was
gathered using in-depth and semi-structured interviews. Thematic content
analysis was used to analyse the data. To evaluate the potential utilisation of fly
ash for sustainable crop production, laboratory analysis of the physical and
nutrient composition of fly ash was undertaken. To evaluate the effects of fly ash
on tomato, cucumber and rape crops, a field experiment was set up. A
Randomised Complete Block Design (RCBD) with five treatments, replicated
three times, was implemented on each of the crops. The analysis of variance was
used for analysing the results. Results showed that dumped and stored fly ash
caused air pollution, groundwater contamination, human health effects and soil
pollution. Fly ash can potentially be used in crop production to control soil-borne
pests and diseases and improve the physical and nutrient characteristics of soil
for improved crop yields. The application of fly ash had a significant effect
(P<0.05) on the growth and yield of tomatoes, cucumbers and rape. The highest
yields were realised at 25% fly ash soil concentration, while 100% fly ash was
toxic.
Description:
The purpose of the Oikos - The Zimbabwe Ezekiel Guti University Bulletin of Ecology, Science Technology, Agriculture and Food Systems Review and Advancement is to provide a forum for scientific and technological solutions based on a systems approach and thinking as the bedrock of intervention.
