Search

Objective: In the highlands of South-Kivu province of DR Congo, cassava is grown on marginal land not suitable for other crops. Walungu territory for instance is dominated by acidic soils and has the highest nutrient depletion rate in the country. On such types of soil, nutrient depletion is accompanied by a decrease in the availability of phosphorus and many other nutrients. The use of Arbuscular mycorrhizal fungi (AMF) would therefore be an alternative to improve the phosphate nutrition of cassava under different soil conditions. Methodology and results: The experiment reported in the current study was conducted in pots under semi-controlled conditions. Ferrallitic soil from Walungu was used. Soil was sterilized or not and then inoculated with the AMF Rhizophagus irregularis (RI) strain. Results showed that inoculation with an exotic AMF strain (Rhizophagus iregularis) has significantly increased root abundance (number of roots) in both sterilized and unsterilized soil and root dry weight in sterilized soil only. However, in unsterilized soil, root dry weight decreased with AMF inoculation. In Walungu acidic soils, P supply could significantly influence the effect of mycorrhizal inoculation on root development and root abundance. AMF inoculation has significantly increased the shoot P concentration when P was supplied. In sterilized soil, mycorrhizal inoculation had a depressant effect on soil phosphorus concentration, especially when P was not supplied. Conclusion and application of results: Our results suggest that the introduced Rhizophagus iregularis strain increases P uptake in the rhizospheric soil, especially when phosphorus is not applied to the sterilized or unsterilized soil. The use of the Rhizophagus irregularis strain as a biofertilizer could improve phosphorus nutrition and root development in cassava. Keywords: Arbuscular mycorrhizae, Rhizophagus irregularis, P uptake, Cassava, Ferrallitic soil

Soil erosion is a major concern for the agricultural production as it leads to topsoil losses and decreased soil fertility, especially in highland regions. Walungu’s Chisheke watershed supports the staple food and industrial tea production, which are the basis for the food and income security in the region. The Chisheke watershed’s soil loss estimate is, therefore, vital for its sustainable management to maximize benefit to farmers and the region economy which is heavily dependent on tea products and sub-products’ export. To facilitate the implementation of an erosion management plan, this study estimated soil losses in the Chisheke watershed using the Revised Soil Loss Equation (RUSLE). Besides, it assessed the land-use and land cover change impacts on the soil erosion as well as the farmer's perception on the currently experienced watershed soil erosion. Results showed that soil losses varied from 0 to 400 t ha−1 yr−1, with an average of 24 t ha−1 yr−1. The soil loss rates depended on the land-use and land cover changes. The highest soil losses were those from settlements (60 t ha−1 yr−1) and bare soils (45 t ha−1 yr−1) while agriculture and tea plantation (8.5 t ha−1 yr−1) and forest (6.5 t ha−1 yr−1) recorded lower soil losses. However, extreme soil erosive risks were observed in steep slope agricultural lands. Farmers acknowledged the soil erosion as a major concern in their area and used the soil and water conservation practices to mitigate its negative effects. The predominant soil and water conservation practices included the manure (72%), compost (57%) and green manure (45%) applications as well as the promotion of mashes and wetlands for vegetable crop production. The soil erosion maps provided in this study are valuable resources to effectively implement sustainable soil erosion management strategies in the Chisheke watershed and other areas with similar agro-ecological conditions.

In South-Kivu province, cattle farming is an integral component of farmers’ livelihoods and one of the few income-generating opportunities for smallholders. However, very few studies have been conducted to characterize smallholders’ cattle production systems. This study documents cattle production systems to better understand their current situation, constraints they face and opportunities they offer. For that purpose, an investigation was conducted based on a structured survey questionnaire and participatory interviews with 863 farmers in South-Kivu province. Collected data were analysed using factorial analysis of mixed data and clustering techniques. The results revealed three types of smallholder cattle farms differing mainly in their herds’ sizes and landholding. The first category is the most common and includes farmers raising small herds (6.3 ± 6.7 cattle) of local breeds in herding system (in this work, “herding system” refers to a rearing system for which the farmer drives and stays with his animals on pastures and fallow land during the day) and grazing fodder in community pastures, fallow lands and roadside grasses, while land constitutes a scarce resource. In the second category, some farmers have small tracts of land ( 5 ha), but all have medium-size herds (45.1 ± 19.4 cattle) made up of local breeds, which they rear in herding system. They also exploit community pastures, fallow land and roadside fodder for animal feeding. The third and last category includes farmers with large cattle herds (78.1 ± 28.1 cattle) of local, crossbred and exotic breeds raised free range in the fenced paddocks on vast areas of land (> 5 ha) found in high-altitude regions. However, while being different according to the above-considered characteristics, the three categories of cattle farming remain extensive pastoral farms dominated by male farmers. Agriculture and/or animal husbandry are their main source of income while their livestock are also composed of goats and poultry, beside cattle. Still, the three farming groups require more inputs and improvement strategies for increased productivity in the challenging environment characterized by low land accessibility and high demand for milk and meat. Fodder cultivation and crop-livestock integration through agro-ecological systems as well as access to credit and extension services are the proposed strategies for the improvement of this economic sector.

Le maraîchage est actuellement un secteur où certaines pratiques d’agriculture moderne comme la culture pure et l’utilisation des produits de synthèse se développent, mais sont de plus en plus questionnées. L’évaluation de la durabilité de ces pratiques n’a pas encore fait l’objet d’études dans les régions montagneuses du Sud-Kivu, à l’Est de la République démocratique du Congo. Pour y remédier, la durabilité de 368 unités de production maraîchère choisies de manière aléatoire et stratifiée a été évaluée grâce à l’outil « Indicateur de la durabilité de la production maraîchère » (IPDM). Les résultats obtenus font ressortir trois types d’exploitations dont 44 % sont de grande taille, 52 % de taille moyenne et 5 % de petite taille. Il a été constaté que, sur un maximum de 100 points possibles, les exploitations de petite taille obtiennent des scores de durabilité de 60 %, 53 % et 57 % sur les trois dimensions respectives de la durabilité : agroécologique, socio-territoriale et économique. Sur toutes ces dimensions, les grandes exploitations n’atteignent pas 50 %. Ces résultats montrent que les grandes exploitations, plus modernes, sont cependant moins durables. Afin de pérenniser le maraîchage au Sud-Kivu, il apparaît donc nécessaire de promouvoir l’intensification écologique, la diversification intégrée et la promotion des intrants locaux auprès des différents types d’exploitation, et en particulier des plus grandes, engagées dans des techniques intensives mais peu durables.

Vegetables play a very important role in rural and urban communities as both food and a business opportunity. They are fast-growing species, with high nutritional values and able to generate income in a relatively short period compared to other crops. A characterization of market gardening systems was carried out with 368 producers from major market gardening sites in South-Kivu, in Easten of the RD Congo.The aim pursued was to assess existing systems and perspectives to enable steady transition to integrated, sustainable and resilient crop systems. The results showed that very few producers in the region practice plant integration. The typology carried out made it possible to identify three classes of market gardening farms based on adopted agronomic practices, production factors and possible outcomes derived from different systems. Most of the surveyed farms practice crop rotation and are market-oriented. However, they majorly differ in terms of farm size, practices of intercropping, permanent agriculture, mulching, production constraints and producer’s perception on the level of production. For instance, producers who are much more into intercropping also cultivate small areas (less than 0.25 ha). Results also showed that variables such as type of labour, cropping system, type of fertilizer used, mulching practice, adoption of permanent agriculture, producer’s perception of the level of soil fertility, and the water source used affect producer’s appreciation of the level of production obtained (p < 0.05). These variables can be mobilized for improvement of the market gardening system towards more sustainable, diversified and resilient systems.