Supplementing grass-based cattle feeds with legume leaves and its effects on manure quality and value as a soil improver for an Anthropic Ferralsol in Rwanda

Combined use of lime, animal manure and inorganic fertilisers is effective in replenishing the fertility of degraded acid soils. However, many smallholder farmers lack access to sufficient amounts of these inputs to improve the fertility and reduce the aluminium toxicity of Ferralsols. Organic manures are available but often have low nutrient content, which limits their ability to supply nutrients to soils. In a two-factor field experiment over four seasons on an Anthropic Ferralsol in Southern Province, Rwanda, we assessed (i) the effect of cattle manure on soil properties at a reduced rate affordable to smallholder farmers compared with that of NPK fertiliser applied, with and without lime also at a reduced rate, and (ii) the effect of supplementing grass in a basal cattle diet with legume leaves on manure quality and its effect on soil properties. Manure from cattle fed only the grassChloris gayana(grass-only manure) and from cattle fedC. gayanasupplemented withAcacia angustissimaleaves (grass+legume manure) was applied at 5 t dry matter ha(-1)(25% of the recommended rate) at the beginning of each growing season. NPK was applied as split doses supplying a total rate of 70 kg N ha(-1). Lime was applied annually at a rate of 2.0 t CaO ha(-1), which was 25% of the rate required to neutralise total acidity at the site. All amendments were applied only to the soil surrounding the maize plants (planting stations), which is estimated at 25% of the plot area. Maize stover was left on plots after harvest and planting stations were retained over all growing seasons. All treatments altered soil properties at the planting stations. Lime generally increased pH but there was no significant difference between lime plus manure treatments and non-limed manure treatments. Soil organic carbon concentration and cation exchange capacity were higher in manure and NPK treatments than in non-fertilised treatments. The manure treatment increased soil water-holding capacity compared with the NPK and non-fertilised treatments. There was no significant difference in total N, Ca2+, Mg(2+)and K(+)between the NPK and manure treatments. Micro-dosing animal manure can thus replace mineral fertiliser plus lime for soil fertility replenishment in smallholder farming. Grass+legume manure contained higher concentrations of total N, Ca, Mg, K and Na than grass-only manure, but its effect on soil properties did not differ significantly from that of grass-only manure

Effect of grass-diet and grass-legume-diet manure applied to planting holes on smallholder maize production in Rwanda

Animal manure provides plant nutrients and also affects soil nutrient availability, pH buffering and soil physical properties through its contribution to soil organic matter pools. However, the quality and quantity of manure are often low on smallholder farms in sub-Saharan Africa and the initial effect of manuring on crop yield may be small or even negative. In a two-factorial experiment over four seasons in southern Rwanda, the fertiliser value to a maize crop of manures produced by cattle fed a basal diet of only Chloris gayana grass or a mixed C. gayanaAcacia angustissima diet was compared with that of NPK 17-17-17 and no fertiliser. The potential liming effect of the manures was also evaluated through inclusion (or not) of travertine as the second factor. All amendments were applied only to maize planting holes. The crop failed in season 1 due to drought, but manure application (5 t ha-1) approximately doubled maize yield compared with the unfertilised control during seasons 2-4, while NPK (70 kg N ha-1) increased yield by 3- to 4-fold, with corresponding improvements in crop performance indicators. The mixed diet increased manure quality and maize yield compared with the grass diet in season 4. Liming showed a consistent tendency to improve crop performance indicators and yield, but significant differences were only identified in some cases, possibly because the pH increase was small. The results suggest that in regions where manure availability is limiting, application of reduced rates only to planting holes may be an efficient technology. Enhanced animal feed can result in higher quality manure, and ultimately increase crop yield, if nutrient losses during manure handling and storage can be limited

Biomass production and nutrient content of three agroforestry tree species growing on an acid Anthropic Ferralsol under recurrent harvesting at different cutting heights

Agroforestry systems may alleviate challenges relating to soil degradation and low livestock production for smallholder farmers. Species-adjusted management regimes will determine how agroforestry fits in farming systems. Long-term productivity of biomass in agroforestry systems managed for fodder production requires tree species that coppice after repeated cutting. This study evaluated the effect of different cutting heights (0.3 and 1.0 m) and repeated harvests (1-5) on biomass production and chemical composition of the leguminous trees Acacia angustissima, Leucaena pallida and Mimosa scabrella in a field study on an Anthropic Ferralsol in Southern Rwanda. Shoot biomass production was highest at 0.3 m cutting height for A. angustissima and L. pallida, but M. scabrella could not survive that cutting height. Shoot biomass was highest for A. angustissima and lowest for M. scabrella, which did not adapt to repeated harvests. Leaf:stem ratio was not affected by cutting height. Cutting height did not affect crude protein (CP), but neutral detergent fibre (NDF), acid detergent fibre (ADF) and total polyphenol (TP) concentrations were higher at 1.0 m cutting height than at 0.3 m. Crude protein was highest in A. angustissima and lowest in M. scabrella, while NDF and ADF were highest in M. scabrella. Although all species provided high feed quality in terms of high CP content at both cutting heights, low cutting height (0.3 m) is recommended for A. angustissima and L. pallida for higher overall quality and biomass production

Leapfrogging with technology: introduction of a monitoring platform to support a large-scale Ebola vaccination program in Rwanda

Continued outbreaks of Ebola virus disease, including recent outbreaks in the Democratic Republic of the Congo (DRC), highlight the need for effective vaccine programs to combat future outbreaks. Given the population flow between DRC and Rwanda, the Rwanda Ministry of Health initiated a preventive vaccination campaign supported by a vaccination monitoring platform (VMP). The campaign aimed to vaccinate approximately 200,000 people from Rwanda’s Rubavu and Rusizi districts with the two-dose vaccine regimen Ad26.ZEBOV, MVA-BN-Filo. The VMP encompassed: biometric identification (iris scanning), mobile messaging, and an interactive reporting dashboard. The VMP collected data used to register and identify participants at subsequent visits. Mobile message reminders supported compliance. To 13 November 2020, the campaign was half complete with Ad26.ZEBOV administered to 116,974 participants and MVA-BN-Filo to 76,464. MVA-BN-Filo should be given to participants approximately 8 weeks after the Ad26.ZEBOV with a compliance window of −14 and +28 days. Of the 83,850 participants who were eligible per this dosing window for the subsequent MVA-BN-Filo vaccine, 91.2% (76,453/83,850) received it and 82.9% (69,505/83,850) received it within the compliance window defined for this campaign. Utilization of the VMP was instrumental to the success of the campaign, using biometric technology, dashboard reporting of near real-time data analysis and mobile phone communication technology to support vaccine administration and monitoring. A comprehensive VMP is feasible in large-scale health-care campaigns, beneficial for public health surveillance, and can allow effective response to an infectious disease outbreak

Trees on smallholder farms and forest restoration are critical for Rwanda to achieve net zero emissions

International audienceAbstract Landscape restoration initiatives are mainly focusing on forest regeneration and agroforestry, especially in the Global South. However, due to a lack of monitoring tools, the carbon balance of restoration efforts remains poorly quantified. Here, we use satellite images from 2008 and 2019 to calculate carbon stocks for individual trees in Rwanda, a country which has been actively engaged in restoration activities over the past decade. We show that smallholder farmers on average planted about 3 trees per farm during 2008–2019, contributing about 50.4 million new trees at the national scale. The overall C sink of the new farmland trees was 0.13 Megagrams of Carbon per hectare per year, which is 6 times lower than gains observed from restoration of degraded forests (0.76 Megagrams of Carbon per hectare per year). If national greenhouse gas emissions remain at the level of 2019, agroforestry (~61% of national area coverage) and continued restoration of degraded natural forests (~0.5% of national area coverage) have the potential to offset about 80% of the national emissions before 2050. Our work monitors and quantifies progress and impact of landscape restoration projects and outlines a pathway to engage smallholder farmers with a limited number of on-farm trees into the expanding carbon market