Problems and opportunities of wetland management in Rwanda

The aim of this research was to identify problems and opportunities regarding management of wetlands in Rwanda, with a focus on their agricultural use. In Rwanda cultivated wetlands cover 148,344 ha and they play an important role in supporting farmers’ livelihood through agriculture. This thesis reveals the extent to which degradation of wetlands negatively affects individuals, households, communities, the national economy and even potentially the greater hydrology of a region. Cyabayaga and Rugeramigozi wetlands were selected as representatives for agricultural wetlands. The rice in Cyabayaga was the largest contributor to household income with $ 1045 per household per season whereas vegetables cultivated in the dry season in Rugeramigozi have high potential as cash crops. Nutrient balances in wetland fields are influenced by agricultural potential, farming system, access to resources, gross margin, size of livestock herd and farmers resource endowment. The marketability of the crops is critical factor in the decision to invest in soil fertility improvement. Legumes and maize yields were lowest on the hillside plots compared to wetlands. Fertilizer application increased grain yield of both legumes and maize and nitrogen fixation, the highest yield was observed in the treatment combining organic and inorganic fertilizers. Maize yield after legume was higher than continuous maize production. The nitrogen balance was negative in both sites at all landscape positions. Findings of this study stress the need of integrated watershed management for improved wetland management.</p

Applicability of conservation agriculture for climate change adaptation in Rwanda’s situation

Improving food security and environmental conservation should be the main targets of innovative farming systems. Conservation agriculture (CA), based on minimum tillage, crop residue retention and crop rotations has been proposed against poor agricultural productivity and soil degradation. This paper discusses the applicability and potential benefits of CA in Rwanda under the unfolding climate change scenario. The potential and benefits from CA may vary with rainfall regime. In high rainfall areas (For example North and West of Rwanda), the soils are susceptible to soil erosion and face fertility decline while in low rainfall areas (For example East of Rwanda) crops fail due to sub-optimal water use efficiency. Furthermore, low organic carbon content lower fertilisers response and government targets of increasing production through Crop Intensification Program, is limited. It has been shown that CA can: Reduce soil loss from 35.5 to 14.5 t/ha/year, have 50-70% greater infiltration and increase 42% of organic carbon. Long term analysis using Agricultural Production System Simulator showed that CA can increase yield from 3.6 to 4.4t/ha in areas having >770 mm. Based on the evidence from regional research, CA has a good potential for climate change adaptation in both high and low rainfall areas of Rwanda. However, decreased yield observed in high rainfall areas, increased labour requirements when herbicides are not used and lack of mulch due to priority given to feeding of livestock constrained CA adoption. We conclude that there is a need for critical assessment under which ecological and socio economic conditions CA is suited for smallholder farming in Rwanda

Implications of tillage practices, management of soil surface and fertilizer application on sustainable dryland agriculture: a case study of Eastern Rwanda

Open Access Journal; Published online: 03 August 2017Conservation agriculture (CA) is becoming popular in sub-Saharan Africa as potential solution to soil degradation. However, most findings are based on large scale, mechanized agricultural production systems which are not easy to apply within the smallholder farmer’s context. This study assessed the implications of tillage practices, management of soil surface and fertilizer application on sustainable dryland agriculture of Eastern Rwanda. The experimental design was Split Plot with 4 replications. The main plots were conventional tillage (CT) and no tillage (NT) and sub-plots were: Control, sole residues application (RR); residues application with inorganic fertilizers (RR+IF) and inorganic fertilizers (IF) applied alone. Inorganic fertilizers application increased bean grain and biomass yield by 103%. In no tillage inorganic fertilizers had higher maize grain and biomass yields whereas residues application had 68% higher maize grain and biomass yield in conventional tillage. The significant increase in organic carbon was observed in residues applied with inorganic fertilizers. There was a significant N decrease in all treatments however control and residues had the highest N pool compared to other treatments. Sole residues application and residues applied with inorganic fertilizers treatment increased significantly Available P. The use of inorganic fertilizers in conservation agriculture systems should be promoted as the engine toward successful of CA practices for Bugesera district conditions. These results provide a basis for conducting trade-off analyses to support the development of CA crop management and international development strategies based on available scientific evidence

Allometric equations, wood density and partitioning of aboveground biomass in the arboretum of Ruhande, Rwanda

Open Access Journal; Published online: 10 Nov 2020There is growing interest in plantation forests throughout Africa because of their role in environment, economy and people's livelihoods. However, the contribution of planted forests to climate mitigation is poorly understood, partly due to lack of allometric equations for biomass estimation. This study aimed to determine wood density and biomass fractions in aboveground components, and to develop biomass estimation equations for multispecies plantation forests in the arboretum of Ruhande in Rwanda. Allometric equations were developed by regressing diameter at breast height (DBH) alone or in combination with height or wood density or age of trees against the biomass of 45 trees harvested from a 200-ha site. Biomass estimates obtained from destructively sampled trees were up-scaled to estimate the amount of carbon stocked in the arboretum of Ruhande, assuming a stem density of 250 stems per ha. Wood density varied among the species but not tree size. The greatest fraction of aboveground biomass was allocated to stems (71–77%) compared to branches (19–27%) and leaves (1–8%) and varied by species. Equations developed fit the data well with DBH explaining over 90% of the observed variation in aboveground and stem biomass. Including height or wood density as supporting parameters reduced the relative error for aboveground biomass by 6.4 and 8.0% and improved model fit by 2.1 and 2.9%, respectively. Akaike information criterion (AIC) showed that wood density (AIC=63.6) and height (AIC=48.2) were the most suitable parameters to support DBH as a proxy for aboveground and stem biomass, respectively. Allometric equations developed in this study are useful tool for estimating carbon stocks of plantation forests in Rwanda and can enhance the accuracy of biomass predictions where site-specific equations rather than generalized models are recommended. Further studies focusing on development of allometric equations on belowground biomass in such systems are recommended

Opportunities and constraints facing fish production system in DR Congo

Open Access ArticleThe current aquaculture production systems in the village environment and their constraints and opportunities were studied to understand the reasons for the decrease in the number of fishponds in South Kivu, eastern DR Congo. . Little is known about fish production in South Kivu; thus, this study was carried out in two phases: a survey, a follow-up of the farms over the course of a year and a literature review. Accordingly, 305 aquaculturists from three territories were interviewed from May to November 2019. This breeding is mainly practiced by men (91.6%), adults (45±14 years), married (93.6%), fish farmers with no formal education (36.5%, ) farmers who practice agriculture as their main activity (68.5%, ) and farmers engaged in fish farming as a secondary activity (60.4%). Fish farmers have 13±9 years' experience; and only 39.0 percent of fish farmers received training on good fish farming practices. Membership to groups or associations is low (6.1%). Tilapia sp is the widely cultivated species (82.6%), followed by a combination of Tilapia-Catfish (17.3%). Fish are reared in medium-sized fishponds (358.7±230.4 m2) at unknown age (60.4%), with a reproduction rate of (54.7±37.7 kg) per growth cycle. The main opportunities in aquaculture in South Kivu are water availability (13.5% in Kabare, 31.1% in the Ruzizi plain, and 15.3% in Walungu), the presence of a fish market, and availability of land suitable for aquaculture (27.1% in Kabare, 10.9% in the plain, and 15.3% in Walungu). On the other hand, the main constraints identified are lack of quality fry (75.5% in Kabare) and the high cost of labour (60.9% in the Ruzizi plain and 60.9% in Walungu)

Assessment of sustainable land use: linking land management practices to sustainable land use indicators

Open Access Article; Published online: 22 May 2021Land degradation threatens food production especially in smallholder farming systems predominant in sub-Saharan Africa. Monitoring the effects of agricultural land uses is critical to guide sustainable intensification (SI). There are various indicators of sustainable land use (SLU), but conventional methods to quantify their metrics are complex and difficult to deploy for rapid and large-scale assessments. Considering that SLU indicators are dependent on agricultural practices, which can be rapidly identified and quantified, we propose a framework for SLU assessment that includes indirect quantifications of prioritized indicators (crop productivity, soil organic carbon (SOC), acidification, erosion, nutrient balance) using agricultural practices; and a SLU index derived from the integration of these indicators. The application of the framework to a case study, consisting of 1319 farm plots in Tanzania, reveals that SOC and N balance were the main contributors to the SLU gap. Only 2.2% of the plots qualified as being used sustainably. The framework proved to be sensitive to practices commonly used by farmers, thus providing an opportunity to identify practices needed to revert land degradation. Further application of the framework as a decision-support tool can enhance the efficiency of SI investments, by targeting practices which effectively enhance food production and preserve land

Estimation of soil erosion risk, its valuation and economic implications for agricultural production in western part of Rwanda

Open Access Article; Published online: 10 Sept 2017Multifunctional soil conservation strategies have the capacity to control soil erosion as well as increase its quality, thus leading to sustained yields as long as planners have knowledge on the severity of soil loss. A comprehensive methodology that integrates Revised Universal Soil Loss Equation (RUSLE) model and Geographic Information System (GIS) techniques was adopted to determine the soil erosion vulnerability within Katabuvuga, Nyamyumba and Mukamira watersheds in western part of Rwanda, with the aim of supporting planning of land and water management interventions. The dominant slop class in all watershed was 16-40% covering 50% in Katabuvuga watershed, 43% in Mukamira watershed and 70.6% in Nyamyumba watershed. High erosion risk was recorded in Mukamira (72 %) and it was followed by Nyamyumba (46 %). The average soil loss in selected watersheds was 32t/ha/year. Among the various studied watershed, highest average loss was reported in Nyamyumba watershed (37t/ha/year) while the lowest average was in Mukamira watershed (28t/ha/year). Soil loss was higher in cropland and lower in settlement. The average loss of nutrients was 1705 kg/ha/year of carbon, 155 kg/ha/year of nitrogen, 3 kg/ha/year of phosphurus and 111 kg/ha/year of potassium, the highest nutrient loss occurred in cropland. Based on the cost of NPK the average value of N lost per ha per year is 167507 Rwandan Francs (Rwf) while the value of P and K loss per ha per year is 3309 Rwf and 120189 Rwf respectively