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In low-fertility tropical agroecosystems, intercropping with perennial legumes has the potential to maximize biological nitrogen fixation (BNF) and improve non-legume nitrogen (N) uptake and yields. However, the microbial interactions that facilitate the beneficial effects of intercropping in perennial systems remain largely uncharacterized, particularly in the tropics. In this study, we explored the contribution of root-associated bacteria and fungi to N content and the nutritional characteristics of perennial grasses (Cenchrus purpureus and Brachiaria cv. Mulato II) and an annual cereal (Zea mays) intercropped with a perennial legume (Desmodium sp). Sampling approximately every 8 weeks at the time of forage grass anthesis, we collected biomass leaf tissue, bulk soil, and rhizosphere soil. We calculated nitrogen derived from the atmosphere (Ndfa) in Desmodium leaf tissue to estimate BNF and found that Ndfa increased in intercropping arrangements relative to single-cropped Desmodium by 91.6–147.1% on average in intercropped stands with Brachiaria and C. purpureus. Intercropping also induced positive changes in non-legume tissue quality in a species- and site-dependent manner. Furthermore, we identified microbial taxa that were significantly enriched in the rhizosphere of intercropped plants relative to monocropped plants and which correlated to multiple forage nutritive quality metrics. Fungal community structure responded more strongly to the presence of a legume intercrop than bacterial communities. We also identified species-specific trends in the degree to which monocropped and intercropped rhizosphere communities differed. Overall, this study suggests that perennial legume intercropping may recruit beneficial rhizosphere microorganisms in rainfed tropical soils to facilitate nutritional benefits in the non-legume companion crop and highlights the complexity of rhizospheric microbial interactions in intercropped systems.

A survey was conducted to assess livestock production systems and their constraints in smallholder dairy farmers in Lowlands and Highlands regions of Rwanda. A semi-structured questionnaire was administered to 247 and 145 households randomly selected in lowland (Rwamagana District) and highland (Musanze District), respectively. A Chi-square test was used to examine associations between categorical variables. Independent sample t-test was used to separate means. Excel Pivot table was used to rank raised constraints. Results showed that agro-ecological location had a significant influence (p

Microbial nitrogen (N) cycling pathways are largely responsible for producing forms of N that are available for plant uptake or lost from the system as gas or leachate. The temporal dynamics of microbial N pathways in tropical agroecosystems are not well defined, even though they are critical to understanding the potential impact of soil conservation strategies. We aimed to 1) characterize temporal changes in functional gene associations across a seasonal gradient, 2) identify keystone genes that play a central role in connecting N cycle functions, and 3) detect gene co-occurrences that remained stable over time. Soil samples (n=335) were collected from two replicated field trials in Rwanda between September 2020 and March 2021. We found high variability among N-cycle gene relationships and network properties that was driven more by sampling timepoint than by location. Two nitrification gene targets, hydroxylamine oxidoreductase and nitrite oxidoreductase, co-occurred across all timepoints, indicating that they may be ideal year-round targets to limit nitrification in rainfed agricultural soils. We also found that gene keystoneness varied across time, suggesting that management practices to enhance N-cycle functions such as the application of nitrification inhibitors could be adapted to seasonal conditions. Our results mark an important first step in employing gene networks to infer function in soil biogeochemical cycles, using a tropical seasonal gradient as a model system.

Diseases have emerged as one of the major challenges of Brachiaria production in Africa. Nine Brachiaria cultivars were evaluated for leaf rust, leaf spot and leaf blight diseases and agronomic per...

Brachiaria (syn. Urochloa) is one of the most important tropical forages grass of African origin. Its performance is affected by different constraints, including diseases. This study assessed the distribution, incidence and severity of Brachiaria diseases and documented farmers’ knowledge on Brachiaria diseases in Rwanda. Surveys were conducted in five districts in the dry and wet seasons of 2018 and 2019. Fungi associated with major diseases were isolated and identified based on internal transcribed spacer sequences. The demographic information and farmers’ knowledge of Brachiaria diseases and yield loss were collected using structured questionnaire. Surveys revealed widespread distribution of leaf blight, leaf rust and leaf spot diseases in Rwanda. Incidence and severity of these diseases differed significantly by districts, seasons and district × season interactions; the exception was the non-significant effect of season and district × season interactions on rust incidence in 2018. Molecular identification revealed Phakopsora apoda as a provisional leaf rust pathogen, and frequent association of fungi Epicoccum spp. and Nigrospora spp. with leaf blight, and Bipolaris secalis and Fusarium spp. with leaf spot symptoms. This study provides baseline information for future studies on Brachiaria diseases and recognises diseases as a major challenge to sustainable production of Brachiaria grass in Rwanda and East Africa.

This study assessed the growth and feed intake performances of Galla goats and their crosses with local goats fed on Brachiaria grass cultivar Mulato II and Napier grass mixed with Leucaena leaf meal. Twenty-four Galla goats and 24 crossbred goats were selected and divided into four groups of three goats for each genotype and put in a partitioned house for goats’ stall feeding. Goats from each group were identified using ear tags, randomised and then allotted one of the dietary treatments. Feed rations used as treatments were hay of Mulato II, silage of Napier grass, Mulato II, ML (67% Mulato + 33% Leucaena leaf meal) and NL (67% Napier grass + 33% Leucaena leaf meal). Individual goat weights were taken on a weekly basis. Feed samples of each diet were collected every week and analysed for nutritive values. The chemical composition of feed showed significant differences (P

Cattle genotypes and adoption of new feeding technology are necessary for improving beef cattle production and managing efficiently beef production costs. A study was conducted to determine the effects of cattle genotypes and levels of concentrate supplements on cost effectiveness of feedlot beef production in a Complete Randomized Block Design in 3×4 factorial arrangements with 4 replications. Feeds were urea-treated rice straw (UTRS: 4%, w/w) and concentrates made from decorticated cottonseed cake (66%) and maize bran (34%). The experimental animals were Ankole (A×A: n=16), Ankole × Friesian (A×F: n=16) and Ankole × Sahiwal (A×S: n=16) steers. Proxy indicators used to determine profitability and likelihood of economic viability were Initial and Final values of carcass existing abattoir price (RwF 1800/kg beef); Break-even scenarios using What-if Analysis in Excel, 2010; and Gross Margin (GM). Results suggested that cost effectiveness of feedlot beef did not differ (p>0.05) by genotype; but they differed (p

This study investigated the effect of cutting height (30 and 100 cm) on chemical composition and in vitro digestibility in field-grown Acacia angustissima (Mill.) Kuntze. (Prairie acacia), Leucaena pallida Britton & Rose (guaja) and Mimosa scabrella Bentham. (bracatinga) legumes and their value in supplementing a basal diet of Chloris gayana Kunth. (Rhodes grass). Cutting height did not affect major chemical composition. Crude protein (CP) was highest in A. angustissima and lowest in M. scabrella, while neutral detergent fibre (NDF) and acid detergent fibre (ADF) were highest in M. scabrella. Degradation parameters were greater at 100 cm cutting height. L. pallida showed high in vitro organic matter digestibility but A. angustissima had the highest metabolisable energy. Addition of A. angustissima, L. pallida and M. scabrella to the basal diet increased improved the nutritional value and increased the CP content from 8.4 to 19.8% and 18.1 and 16.1%, respectively. Cutting height of A. angustissima, L. pallida and M. scabrella had no effect on their nutritional value. Their other functions and benefits will determine choice of cutting height as management practice when used on farms. Key words: Legume trees, cutting height, chemical composition, in vitro degradability.

Rearing heifers for dairy cow replacement is a challenge in smallholder dairy farms in the tropics due to feed shortage. The objective of this study was to evaluate Brachiaria hybrid cultivar Mulato II as a forage resource for improving growth performance of dairy heifers under cut-and-carry feeding system in Rwanda. Sixteen crossbred (Ankole × Jersey) heifers (mean weight 203 ± 35 kg) were randomly allocated to two dietary treatments viz: Mulato II with 2 kg/day of commercial concentrates (MCC) and Napier grass (Pennisetum purpureum) with the same supplement (NCC), for a period of 12 weeks. Mineral lick and water were provided ad libitum. Daily feed intake and fortnightly live weight were measured. Average daily gains and feed conversion ratio (FCR) were calculated. Results showed that absolute daily dry matter intake (g DMI/day) and relative intake (g/kg of metabolic body weight--BW(0.75)) were higher in heifers fed on MCC than in heifers fed on NCC (P0.001). FCR was lower (P0.001) in MCC than NCC diets. Final body weight (FBW) and body weight gain (BWG) did not differ between the two groups of heifers (P0.05). Average daily weight gain (ADWG) also not differed significantly (P0.05). Based on numerical body weight changes and nutritive values, Mulato II showed potential to be integrated into local cut-and-carry feeding systems for better heifer rearing to facilitate dairy cow replacement.

Chapter 8 shows the importance of integrated crop–livestock systems as potential sources of livelihood to millions of smallholder farmers in arid and semi-arid lands. The systems represent a key solution for enhancing the agricultural productivity, ensuring food and nutritional security and safeguarding the environment through sustainable intensification and prudent use of natural resources. This chapter reviews major crop–livestock farming systems covering feeds and feed systems in arid and semi-arid lands, forage grasses, legumes and crop-residues as well as the benefits of the integrated crop–livestock systems to smallholder farmers. The chapter presents successful cases of farmers’ innovative practices of crop–livestock integrated systems that offer opportunities for increasing agricultural productivity and environmental sustainability in fragile ecological systems. Finally, the chapter provides key policy recommendations based on the best cases and experiences from arid and semi-arid lands also relevant for similar other regions.

Smallholder dairy farmers in Rwanda use diversity of resources to cope with endemic feed shortages. However, there is inadequate real farm data to support farmer decisions on choices of options. The main objective of this study was to evaluate nutritional quality of feed types that farmers use in different agro-ecological zones of Rwanda. Samples of feed types were collected from 90 randomly selected households in the low- and mid-high-altitude zones of Rwanda and analysed for proximate composition, contents of metabolisable energy (ME), organic matter digestibility (OMD) and neutral detergent fibre digestibility (NDFd). Rumen fermentation characteristics and efficiency of energy utilisation were examined by determining partitioning factor (PF). Results showed that only five out of 24 feed types were common in both districts. Chemical composition, OMD, ME, NDFd and PF of these feed types differed significantly (P

Species of the genus Brachiaria originate primarily from Africa, where they are constituents of natural grasslands. Due to their adaptation to acidic, low-fertility soils, millions of hectares of Brachiaria species have been sown as improved pastures in South and Central America, especially B. brizantha cv. Marandu and B. decumbens cv. Basilisk. Due to B. decumbens' susceptibility to spittlebug insect pests in the Americas, CIAT in Colombia and EMBRAPA in Brazil initiated breeding programmes in the 1980s. First cultivars released from CIAT's breeding programme – cvs. Mulato and Mulato-II – have also been investigated in African countries. They have been examined for integration in conservation agriculture systems (Madagascar), for drought and acidic soil tolerance (Rwanda) and for intercropping forages in dairy systems (Uganda, Madagascar), among others. Seed sales to African countries suggest that an area of at least 1,000 ha has been sown so far. The largest adoption of cv. Mulato-II is currently happening in eastern Africa, where it is used by over 20,000 farmers as a trap plant in the push-pull system for control of maize stem borers and parasitic Striga weed. Cv. Mulato-II's particular advantage is its relatively high crude protein content due to greater leafiness and thinner stems than those of traditional Napier grass, resulting in higher nutritive quality. Yet new pest challenges have emerged, requiring further research attention. Diverse hybrids are in the pipeline for release, among them those that are suitable for cut-and-carry systems which are prevalent in eastern Africa. This paper reviews research, development and incipient adoption of new Brachiaria hybrids in African countries.

This study was planned to analyse the basis that make Brachiaria species with greater feeding value than Napier grass (Pennisetum purpureum) for lactating dairy cows. Forty lactating crossbred cows were stall-fed on Brachiariabrizantha cv. Piatá or Napier grass cv. French Cameroon supplemented (mixed on fresh matter basis) or unsupplemented with Desmodium distortum, a forage legume. All cows were fed on fresh matter basis under small-holder farming conditions. Results showed that B. brizantha cv. Piatá had higher contents of dry matter (DM), crude protein (CP) and organic matter (OM), but lower contents of neutral detergent fibre (NDF) and acid detergent fibre (ADF) than Napier grass (P

Animal feed resources remain a major constraint for livestock development in tropical Africa. In Rwanda, grazing lands are shrinking sharply because crop cultivation is progressively encroaching on grazing areas with increasing human pressure (Mutimura and Everson 2011). Therefore, over 60% of households cultivating less than 0.7 ha, and owning livestock, practize zerograzing, where farmers cut-and-carry forage and crop residues to feed animals that are kept exclusively under sheds (MINAGRI 2009). In general, the main feed for dairy cattle under a zero-grazing system is Napier grass (Pennisetum purpureum). For more than a decade, efforts to improve the feed resource base and feeding management have been based on the introduction, characterization and evaluation of exotic forage species, including grasses and legumes. The main aim of this study was to identify and document the status of improved forages as animal feed resources and for use in environmental protection in Rwanda.

beef production, and as a result improve livelihoods and Climate change is a global phenomenon with severe negative impacts on poor people in developing countries (Morton 2007). Across many parts of Africa, rural poor communities rely for their survival on agriculture and livestock, which are amongst the most climate-sensitive economic sectors. Climate-smart agriculture helps farm-ers to increase food production, become more resilient to climate change and reduce greenhouse gas (GHG) emis-sions. The main anthropogenic GHGs are carbon dioxide (CO

The purpose of this study was to assess women’s decision-making power in small-scale agriculture in six African countries in view of the feminization of agriculture and to discuss the meaning of decision-making in relation to women’s empowerment and sustainability. The data are drawn from a multisite and mixed-method agricultural research and development project in six sub-Saharan countries including two sites in each country. The five domains of empowerment outlined in the Women’s Empowerment in Agriculture Index are used to structure the analysis. The results indicate that in the selected sites in Malawi, Rwanda and South Africa, women farmers tend to dominate agricultural decision-making, while the result is more mixed in the Kenyan sites, and decision-making tends to be dominated by men in the sites in Tanzania and Ethiopia. Despite women participating in agricultural decision-making, the qualitative results show that women small-scale farmers were not perceived to be empowered in any of the country sites. It appears that the feminization of agriculture leads to women playing a more important role in decision-making but also to more responsibilities and heavier workloads without necessarily resulting in improvements in well-being outcomes that would enhance sustainability.