Optimization of Soil Fertility Under Banana-Coffee- Livestock and Maize-Legume Residues Transfer Farming Systems on the Slopes of Mount Kilimanjaro, Tanzania
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Date
2025-08
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NM-AIST
Abstract
Arable land is under more pressure due to consequences of climate change and the growing global human population. Among other things, soil fertility has been most negatively impacted. This study aimed at optimizing nutrient management on the slopes of Mount Kilimanjaro for optimal crop production. The area is distinguished by two major farming systems: the banana- coffee-livestock on the highlands [> 1000 meters above sea level (m.a.s.l.)] and maize-legumes on the lowlands (< 1000 m.a.s.l.) of the slope. Data on soil nutrient management was gathered through a household survey. Soil nutrient quantification was done to assess nutrient balance highland-lowland farming systems. A field experiment was conducted in maize-legume farming to optimize soil nitrogen through inorganic fertilizer and cattle manure. The cost
benefit of the existing farming systems by smallholders were assessed. The demographic results showed that most of agricultural practitioners are adults (> 40 years). The findings showed that the levels of organic carbon (1.22%) and nitrogen (0.14%) were significantly lower (p<0.01) in the lowlands. Additionally, both the highlands and lowlands had considerably reduced extractable phosphorus (P) levels, measuring 9.3 mg kg-1 and 8.2 mg kg-1, respectively. The highland had significantly (p<0.01) less potassium (K+) [0.34 cmol (+) kg-1] than the lowland [0.93 cmol (+) kg-1]. The highlands had a negative balance of N and K, while the lowlands had negative balances of all three nutrients (N, P, and K). The field experiment results showed a significant increase in maize crop yields upon N fertilization, with the highest application rate of urea (75 kg N ha-1) producing the highest grain yields of up to 4.21 and 4.32 t ha-1 in the 2021 and 2023 seasons, respectively. In the lowlands, applying manure resulted in increases in soil total N, OC, extractable P, and exchangeable K of 16.67%, 18.13%, 20.95%, and 6.76%, respectively. The highland farming systems have shown high benefit cost ratio (3.79) compared to lowland (1.20) farming systems. Apart from the efforts of the smallholder farmers on soil fertility management, the study concludes that the sustainability of farming systems on the slope of Mt. Kilimanjaro is at stake, which eventually threatens food security.
Therefore, integrating organic and inorganic inputs can significantly improve crop yields and soil health sustainably.
Sustainable Development Goals
SDG: 2- Zero Hunger
SDG :13- Climate Action