Uganda, boasting a primarily tropical climate with historically predictable rainfall patterns, is now confronting the disruptive consequences of climate change.
The country’s once-stable seasons have been flipped over, leading to fluctuations in rainfall duration and intensity, as well as intensified droughts, particularly impacting the eastern and north-eastern regions.
With the looming specter of climate change casting uncertainty upon Uganda’s agricultural sector, the urgency to enhance soil resilience has taken center stage. Amid these challenges, securing food availability and sustainable livelihoods has become paramount.
The climate challenge
Uganda’s agriculture, which heavily relies on rain-fed systems, faces a dual challenge: increasing drought and flood events that disrupt planting and harvesting, and the gradual rise in temperatures that affect crop growth.
Soil degradation further exacerbates these problems, leading to reduced yields and compromised ecosystems.
According to World Bank statistics, the average temperatures in Uganda have been increasing at a rate of 0.28°C per decade, and daily temperature observations show significantly increasing amounts of hot days and nights every year.
Uganda is taking bold steps to combat climate change with its latest Nationally Determined Contribution (NDC). Apart from raising greenhouse gas reduction from 22 percent to 24.7 percent by 2030, the plan includes an array of additional targets.
Among these targets are plans to irrigate 152,622 hectares of land, restore 2.5 million hectares of forest landscape, and raise climate change awareness among 11 million people, among others.
Conservation agriculture is an eco-friendly farming approach that prioritises minimal disruption of soil, continuous soil cover, and plant variety diversification.
This method boosts biodiversity and natural processes in and below the soil, leading to efficient water and nutrient use and better crop yield.
There are three key principles at the core of conservation agriculture including limited soil disturbance where the soil structure is minimally disturbed, often achieved through practices like no-till farming.
There is also persistent soil cover where the soil surface remains covered by crop residues or cover crops, which are crucial for stability and enriching soil properties.
Crop variety diversification where crop rotations involve different plants with varying root depths, can be applied.
The concept of keeping the soil covered is central. Crop residues remain on the surface, supplemented by cover crops when needed. Cover crops, grown during non-crop periods, contribute to soil fertility and stability. They grow between harvesting and planting commercial crops, using leftover soil moisture.
Crop rotation is vital for maintaining diverse soil life and nutrient cycling.
Different crops are planted in succession, each contributing unique organic substances that attract various beneficial microorganisms.
This diverse ecosystem enhances nutrient availability and prevents the buildup of crop-specific pests and diseases.
Crop rotations are designed to meet multiple goals, such as food and fodder production, pest control, weed management, and nutrient enrichment. The sequence involves at least three different crops, creating a dynamic and sustainable farming system.
Joshua Aijuka, an agroecologist at Participatory Ecological Land Use Management (PELUM) Uganda says such practices are the only secure approach to maintaining soil health.
“Both restoring and maintaining soil health are essential to making agriculture viable in the long-term,” he says.
PELUM Uganda is part of a 12-country strong association of civil society organizations in Eastern, Central and Southern Africa working in the area of participatory ecological land use management.
“The rotation of crops, for instance, is not only necessary to offer a diverse diet to the soil microorganisms, but as they root at different soil depths, they are capable of exploring different soil layers for nutrients,” adds Aijuka.
Agroforestry, the integration of trees and crops, offers numerous benefits. Trees provide shade, enhance water retention, and act as windbreaks. They also contribute to carbon sequestration, an essential step in reducing greenhouse gas emissions and combating climate change.
Agroforestry systems work alongside other techniques, such as cover crops, minimal or no tillage, nutrient management, and crop rotation, to enhance soil health.
This sustainable land management approach has been supported by strong evidence gathered globally over four decades.
In agroforestry, the introduction of trees contributes to soil improvement by adding organic material in the form of litter both above and below the ground.
Soil organic matter serves as a vital energy source for soil organisms, impacting soil biodiversity and biological functions. Consequently, soil health assessment often relies on indicators such as soil organic carbon.
Dr Alice Nambuya, an agroforestry scientist at National Coffee Research Institute (NaCORI) in Mukono District says the practice is helpful in mitigating climate change.
“Agroforestry can accumulate greater amounts of carbon and can help maintain soil fertility through a more efficient cycling of nutrients and a reduction of losses through leaching and erosion,” Dr Nambuya says.
Organic matter enrichment
The culmination of organic matter decay within the soil gives rise to an intricate blend of relatively stable compounds collectively referred to as humus.
Typically constituting around 60 to 80 percent of the total organic matter present, humus is accompanied by recent organic litter like partially decomposed litter, deceased roots, and the excretions of soil-dwelling fauna.
The path to revitalising soil organic matter involves a dual approach: limiting soil disruption while optimising nutrient and water provision to amplify plant productivity and uphold residue preservation.
The decline of organic matter in soil initiates a detrimental cycle of deterioration, impacting both food security and environmental integrity, often spanning across regions.
Counteracting this decline through carbon sequestration has the potential to inaugurate a virtuous cycle of productivity enhancement.
Enhancing the uppermost soil layer with organic matter mitigates susceptibility to compaction, crust formation, and erosion, thus positively influencing downstream environmental conditions. Moreover, this enrichment augments soil quality in terms of permeability, aeration, seed germination, and plant nourishment.
Climate change could decrease staple crop yields by around 30 percent due to reduced productivity and crop failures.
The combination of population growth and shifts towards meat and dairy consumption in developing nations will intensify the strain on natural resources and amplify food production challenges. To address these issues, farmers must adapt their practices by planting drought-tolerant and heat-resistant crop varieties.
Participatory plant breeding, involving local farmers in selecting suitable crop types, can ensure that traditional knowlege intersects with modern science.
Embracing climate-resilient crops, such as fast-maturing cereals, heat-tolerant variants, drought-resistant legumes or tubers, plants with better salinity tolerance, or rice capable of surviving submersion, can empower farmers to navigate climate-related shocks.
Climate changes in Uganda
According to World Bank statistics, the average temperatures in Uganda increasing at a rate of 0.28°C per decade, and daily temperature observations showing significantly increasing amounts of hot days and nights every year.