Land suitability analysis for banana and maize under changing climate in Mbale and Nakaseke districts, Uganda
Ngubwagye, Joseph Mukasa
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Smallholder farmers in Mbale and Nakaseke districts, like in the rest of Uganda, continue to grow crops anywhere without paying attention to the soil and climate conditions. Traditional management practices for banana and maize have grown increasingly unsustainable due to climate change. This study analyzed the soil and climate conditions for banana-maize systems to (i) develop current suitability maps for banana and maize; (ii) determine the crop management practices for the banana-maize systems under different land suitability classes; and (iii) develop mid-century suitability scenarios for banana and maize. Soil properties were analyzed ties in the laboratory, results of which were used in suitability analysis. Historical climate data (1980 – 2010) was used as current climate. Analysis was done in a GIS environment. Current suitability classification was done in reference to FAO’s factor ratings (suitability classes) of “Highly Suitable” (S1), “Moderately suitable” (S2), “Marginally suitable” (S3) and “Not suitable (N)”. Evaluation of farming systems was achieved through questionnaire interviews and field visits. Future climate suitability scenarios were obtained using five General Circulation Models (GCMs) based on AgMIP group predictions for Uganda for RCPs 4.5 and 8.5. Only Organic Matter (p<0.019) and Phosphorous (p<0.009) showed a significant variation between the maize and banana fields in Mbale district. More maize farms were recorded in the “Marginally suitable” areas (66.67%) than in the “Moderately suitable” areas (33.33%). Banana farms were recorded in “Highly suitable” areas (66.67%) and 33.33% recorded in “Not suitable” areas in Nakaseke district. Both crops recorded a high prevalence in the two districts (73% and 70% respectively for Nakaseke, and 47% and 87% respectively for Mbale) compared to other crops. Only mono-cropping and intercropping systems were recorded in both districts. “Moderately suitable” and “Highly suitable” areas for banana in Mbale district registered a reduction in size for future climate suitability projections by 11.4% and 85.8% respectively for RCP 4.5, and 12.2% and 85.9% respectively for RCP 8.5. Future climate suitability projections for banana in Nakaseke district showed a reduction in all but “Not suitable” class; it increased by approximately 61.7%. Unlike in Nakaseke where both “Moderately suitable” and “Highly suitable” areas registered a reduction in size for maize, only “Highly suitable” class recorded a reduction in Mbale district. The study recommends suitability maps for the different crops to be availed to farmers as well as increased input use for agriculture in Nakaseke district.