Rwanda Journal of Agricultural Sciences

Variations of soil properties along slope positions in Nyabihu, Rubavu, Ngororero and Rutsiro Districts of Western Rwanda: A baseline soil study for regenerative agriculture

Fri, 20 Sep 2024 00:00:00 +0000

This study aimed at characterizing soil properties and their variations along slope positions in Western Rwanda. It served as a baseline on regenerative agriculture practices introduced by Netherlands Development Organization (SNV) in the Districts of Nyabihu, Ngororero, Rubavu and Rutsiro. Soil samples were collected in a zig-zag pattern at 20 cm depth in triplicates at the top, middle and bottom of slope. Soil texture and chemical properties (pH, Soil Organic Carbon (SOC), total nitrogen, available phosphorus, exchangeable K⁺, Ca²⁺ and Mg²⁺) were analyzed. Results demonstrated that soils of Western Rwanda are mostly fairly acidic (pH5.3 - 6.0) except those in the bottom slopes of Ngororero and Rutsiro which are very acidic (pH4.7 and pH5.2 respectively). The SOC is high in Nyabihu (12.5 – 13.7%), moderate in Rubavu (4.1 – 5.2%) and Rutsiro (4.9 – 5.6%) and low in Ngororero (2.3 – 2.6%) with non-significant differences between effects of slope positions. Total N (0.02 – 0.11%), available P (4.33 – 22.47 ppm) and exchangeable K+ (0.07 – 0.59 cmol (+) kg^-1) levels are weak while exchangeable Ca²⁺ (5.00 – 12.33 cmol (+) kg^-1) and Mg²⁺ (7.50 – 21.11 cmol (+) kg^-1) are moderate to high. There are non-significant effects of slope positions observed. The soil texture is Sandy Loam and Sandy Clay Loam (52.67 – 70.67% sand, 10.67– 29.33% silt and 6.00 – 23.33% clay) which implies a good soil drainage leading to good soil health. The slope positions do not significantly influence soil properties in the study area. Many of the properties are weak and require improvement through regenerative agriculture practices.

Influence of Bioslurry and Nitrogen Fertilizer on Soil Properties and Maize (Zea mays L.) Performance in Terraced Lixisols of medium and Acrisols of high altitudes in Rwanda

A. Fashaho, J. Uwihirwe, S. M. Mwonga, J. J. Lelei2, G. M. Ndegwa — Fri, 20 Sep 2024 00:00:00 +0000

Land terracing is promoted as a management practice for effective soil conservation in hilly areas. However, terraced lands are likely to have low crop productivity where management practices, especially fertilizer application, do not consider changes in soil properties following terracing. This study aimed to determine effects of integrated application of bioslurry and mineral nitrogen (N) rates on soil biochemical properties and maize growth, N uptake and yields in terraced medium and high altitudes areas of Rwanda. A factorial experiment in Randomized Complete Block Design with three replications was set up in two sites. Bioslurry rates of 0, 6, 12 and 18 t ha^-1 at medium altitude and 0, 5, 10 and 15 t ha^-1 at high altitude sites were combined with 0, 30, 60 and 90 kg N ha^-1. Results showed that bioslurry rates of 12 - 18 t ha^-1 in medium altitude and 10 - 15 t ha^-1 in high altitude sites combined with 60 - 90 kg mineral N ha^-1 resulted in significantly (P<0.05) higher plant heights, N uptake and grain yields of 7.8 - 8.0 t ha^-1 and 6.9 - 7.3 t ha^-1 in medium and high altitudes sites, respectively. Their residual main effects resulted in higher bacteria and fungi populations. Bioslurry and N fertilizer applications should be adjusted from current recommendations for increased maize yields in terraced Lixisols and Acrisols of medium and high altitudes areas.

Effects of plant doctors training in strengthening plant health services in Rwanda

P. Murekeyimana, B. Uzayisenga, J.D. Nsabimana, M. Mutimura — Fri, 20 Sep 2024 00:00:00 +0000

Pests and diseases cause devastating losses to global crops each year, severely impacting food security. Effective management of plant health issues is crucial to ensure an abundant supply of safe food. Agricultural extensionists were trained as “Plant Doctors” to advice farmers on managing plant pests and diseases. A study aimed to assess the effectiveness of this training offered to plant doctors and identify areas for improvement. A sample of 30 agronomists trained as Plant Doctors and 30 untrained agronomists were purposively selected from 30 districts in 2022. Data, both qualitative and quantitative were collected using a structured questionnaire and the Plantwise Online Management System. Data analysis was conducted using Statistical Packages for Social Sciences (SPSS). Findings showed that all Plant Doctors were confident in providing plant health recommendations, with 80% of respondents confirming that they could detect and address pests and diseases in a timely manner. Furthermore, 88.3% of respondents indicated that Plant Doctors promoted the proper use of pesticides, while 93.3% agreed that the training contributed to increase agricultural production, both in terms of quantity and quality. Respondents suggested that Plant Doctors should be equipped with plant clinic tools for better service. Additionally, 85% of untrained agronomists expressed a strong desire for training in the diagnosis and management of pests and diseases. We recommend the capacity-building initiatives for all agricultural agents, as this could contribute to the reduction of biotic and abiotic crop challenges.

Factors affecting the success rate of artificial insemination in smallholder dairy production in selected regions of Rwanda

Fri, 20 Sep 2024 00:00:00 +0000

Accessibility of improved dairy genetics in Rwanda is still limited, mostly, by poor success rate of artificial insemination (AI) and dairy management practices. The present study was conducted to assess factors affecting the effectiveness of AI in smallholder dairy production systems in Gicumbi, Nyanza, and Rwamagana districts. A total of 257 cows and heifers from 234 farmers were assessed and recruited for artificial insemination. Information on health and production statuses of the animals was recorded and a trans-rectal ultrasonography was used to test conception rate (CR) from 60 to 80 days after artificial insemination. Collected data were analyzed using Statistical Package for Social Sciences Version 26. Factors with Chi-square, and p-value ≤ 0.05 were included in multiple logistic regression to identify factors with higher association with CR. Results showed that average AI success rate in the study area stands at 45.1%. Age between three to six years (p-value 0.002) and natural estrus (p-value 0.000) showed higher conception rate in this study. Similarly, the presence of three estrus signs and time for artificial insemination showed a positive association with conception rate. The findings of this study showed that natural heat detection, age of the cow, proper time for insemination, heat signs management, and breeds would be taken into consideration in breeding programs to increase AI success rate.

Impact of Senna spectabilis on soil properties: Evidence from the Mayaga and Eastern Savannah in the Eastern Province of Rwanda

Fri, 20 Sep 2024 00:00:00 +0000

This research assesses the impact of Senna spectabilis on soil properties. Laboratory analysis of soil samples was carried out. Samples were collected from 16 sites of Mayaga and Eastern Savannah Agro-ecological zones in the Eastern Province of Rwanda. From each site, a composite soil sample under the tree canopy (treatment) as well as a control composite sample was taken away from trees. Each sample was taken at a depth of 0-30 cm. Results show that Senna spectabilis has various effects on soil. It increases soil nutrients such as Nitrogen, Phosphorus, Potassium, Calcium and Magnesium. It has improved the soil organic carbon (50%), soil aggregate stability (9.1%), soil pH (7.0%), and soil moisture content (23.9%). Moreover, it reduces the exchangeable acidity (20%). Our findings validate the hypotheses that Senna spectabilis has a positive effect on soil chemical, and physical properties. Although the results suggest planting more Senna spectabilis in agroforestry systems due to its capacity to improve soil properties, further research could focus on assessing factors that affect its adoption by farmers and studying nutrient dynamics beneath its canopy as well as its nutrient uptake patterns.

Phenotypic characterization of the Rwandan stinging nettle (Urtica massaica Mildbr.) with emphasis on leaf morphological differences

Fri, 20 Sep 2024 00:00:00 +0000

Patterns of intraspecific variation based on environmental conditions in which populations live may reflect adaptive responses to their habitats. The Rwandan stinging nettle (Urtica massaica Mildbr.) plant grows in most parts of Rwanda both in the wild and domestication forms. While the plant can easily be identified through its leaves and life form, it has been observed that the leaf morphology slightly varies from one region to another. This study aimed to investigate morphological variations, particularly in leaf morphology of the Rwandan stinging nettle (Urtica massaica Mildbr.) growing in the highland, midland, and lowland. Specimens of the stinging nettle were taken from different sites located in the three altitudinal zones. The stinging nettle plant heights and leaf lengths varied from one site to another with 1m, 3.3m, and 1m as mean plant height for highland, midland, and lowland respectively; and 5.14cm, 16.17cm, and 19cm as mean leaf length for highland, midland and lowland respectively. The statistical analysis revealed that the average plant heights, as well as leaf lengths of mature stinging nettle samples from highland, midland, and lowland, were significantly different (p<0.05). The results also showed that there were morphological differences, particularly in leaves among the three altitudinal zones. The most prominent difference was in the main vein length of the stinging nettle with 12.37cm, 19.43cm, and 16.25cm as the mean overall main vein length for highland, midland, and lowland respectively. Changes in leaf morphology can be linked to differences in environment conditions and nutrient availability between the three habitats which could have enabled the species to evolve differently. However, there is a need for further research to examine the heritability of the observed phenotypic changes for future populations of Urtica massaica plant in Rwanda.

Farmer-managed French bean biochar trials in Rwanda: Effects on yield and soil nutrients

S. Uwingabire, J. Nduwamungu, G. Nyberg, S.A.O. Chamshama — Fri, 20 Sep 2024 00:00:00 +0000

In pursuing sustainable and environmentally friendly agricultural practices, using biochar derived from Top-Lit Up-Draft (TLUD) stoves in agriculture has gained significant interest. Biochar (B) from TLUD was applied in furrows in 60 kitchen gardens of French beans (Phaseolus vulgaris) using randomized paired design at a rate of 3 tons/ha in Rwanda’s Huye and Bugesera districts. Data on yield and the soil properties were collected and analyzed using One-way analysis of variance (ANOVA) within a generalized model in R, followed by Tukey’s test (P<0.05). The results showed a consistently positive response in French bean yield following a onetime biochar application in both sites. In Bugesera, yields were 21.6 t/ha in season 1, 24.1, and 28.8 t/ha in season 3. In Huye, yields were slightly lower with 21.6t/ha, 24.3t/ha and 27.3 t/ha for season 1,2 and 3 respectively. The soil's chemical properties in treated and control plots ranged as follows: pH 4.9–7.4, available phosphorus 1.3–8.3 ppm, total nitrogen 0.1–0.4%, calcium 3.3–7.6 cmol+/kg, magnesium 0.04–1.7 cmol+/kg, potassium 0.02–0.7 cmol+/kg, and cation exchange capacity 7.3–13.3 cmol+/kg. Biochar application significantly increased soil porosity by 15.2% and plant-available water by 24.1%, while reducing soil bulk density by 15.3% compared to the control. It is evident from the results that biochar improves soil fertility, boosts french bean yield, and support sustainable farming and energy practices. This technology promotes the use of biochar in soil management and suggests that adopting TLUD stoves can enhance energy sustainability by reducing fuel consumption.

Effect of fermentation on nutrients and phytonutrients content of potatoes (Solanum tuberosum L.)

Fri, 20 Sep 2024 00:00:00 +0000

The aim of this study was to investigate the effect of fermentation on potato nutrients and phytonutrients. Potatoes were washed, sliced and 140g were submerged in jars of 500ml containing 300ml of 2% brine solution. The jars were closed with lids and allowed to ferment spontaneously for 7 days. There was no interaction effect for moisture, starch and protein, while a significant effect was observed for phytonutrients and minerals at P<0.05. Moisture content ranged from 75.89 to 80.44%, starch from14.45 to 18.87% and protein ranged from 1.87% to 2.09%. Total phenols ranged from 11.98mg/100g for fermented Kinigi to 14.90mg/100g for non-fermented Kirundo, total anthocyanins ranged from 0.05mg/100g for fermented Mabondo to 0.92mg/100g for non-fermented Sangema. Vitamin C ranged from 1.29mg/100g for fermented Sangema to 12.14mg/100g for non-fermented Kinigi. There was a change in minerals during fermentation, calcium from 8.11mg/100g to 2.15mg/g, zinc from to 0.32 to 0.10 mg/100g, magnesium from 20.48 to 7.40mg/100g, iron from 0.86 to 0.17mg/100gram, potassium from 542.88 to 299.19mg/100gram, phosphorus from 69.77 mg/100g to 28.22 mg/100g. Fermentation reduced nutrients and phytonutrients in potatoes, potentially due to leaching into fermenting solution or utilization as substrates of fermenting microbes. However, fermentation may also generate bioactive compounds along with flavor that impart health benefits and enhance palatability for consumers.

Morphological Traits as Predictors of Litter Decomposition in Agroforestry Tree Species of Rwanda

Fri, 20 Sep 2024 00:00:00 +0000

This study examines the influence of key morphological traits and how the leaf traits are essential for understanding the strategies of biomass decomposition at the leaf trait level. Leaf thickness, leaf area, specific leaf area, and leaf dry matter content were morphological traits, and lignin and tannin were quality traits affecting litter decomposition, measured across six agroforestry tree species. We applied linear mixed models to quantify the effects of these traits on decomposition, treating species as random effects to account for interspecies variability. Principal Component Analysis revealed that the first principal component, which explains 45.6% of the total variance, is strongly associated with leaf thickness and dry matter content. These traits emerged as the primary drivers of variance in litter decomposition rates. The second principal component, accounting for 26.4% of the variance, is primarily influenced by Leaf Area and Lignin content, indicating their significant roles in the secondary variation observed among species. The total linear mixed model, incorporating all morphological traits, provided a significantly better fit than the reduced model, as indicated by a Chi-square test (p < 0.05). This suggests that combining morphological traits is crucial for understanding litter decomposition dynamics. Moreover, the results highlight species-specific differences in trait effects, emphasizing the need for tailored management strategies in agroforestry systems to optimize nutrient cycling. These findings contribute to a deeper understanding of the factors influencing litter decomposition, offering practical insights for selecting tree species that enhance soil fertility through improved decomposition rates. The study underscores the importance of considering both trait variability and species identity to optimize agroforestry practices for sustainable land management.

Understanding the factors influencing smallholder farmers's willingness to adopt agroforestry in Gomba Village, Rwanda

X. Urayeneza, L. Klapwijk, C. Bucagu, E.N. Bapfakurera — Fri, 20 Sep 2024 00:00:00 +0000

Agroforestry practices are crucial in promoting sustainable agriculture, increasing biodiversity, and enhancing farmers' livelihoods. However, despite extensive research and extension efforts, smallholder farmers' adoption of agroforestry practices in Rwanda remains low. This study examined farmers' agroforestry preferences and factors influencing their adoption in Gomba Village. The data was collected through a survey and focus group discussion with households in Gomba Village, using stratified sampling and classifying them into three wealth groups (better-off, medium, and poor). The results indicated that socioeconomic factors play a significant role in agroforestry adoption, whereby wealthier households (better-off) had high number of trees, wirh mean total of 80 trees per households, followed by medium farmers with 54 trees poor farmers with 40 trees. Fruit trees, present in 85% of households, were the most popular tree species among farmers. The most popular fruit tree species were Persea americana (74% of households), Carica papaya (65%), and Mangifera indica (56%). Multipurpose trees, such as Grevillea robusta and Vernonia amygdalina, were also widely used because they provide essential products like stakes and fodder. The number of tree species increased with farm size, with better-off farmers having an average of 11 tree species versus 9 and 8 for medium and poor farm types. However, several factors limited the adoption of agroforestry. The main challenges were a lack of tree seedlings, labor shortages, and small farm sizes, with poor farmers facing the most constraints. The high cost of seedlings, particularly for grafted fruit trees, posed a significant barrier to adoption. Strategies for widespread adoption of these sustainable land management practices should prioritize improved input access, strengthened extension services, and agroforestry adoption incentives.

Assessment of soil and water physical and chemical properties for crop production in the Nyarubogo irrigation scheme, Rwanda

J.B. Tuyisabe, F.R. Silungwe, H.F. Mahoo — Fri, 20 Sep 2024 00:00:00 +0000

Agricultural production is significantly influenced by the soil and water quality, especially in irrigation systems, where poor management may result in degraded soil and lower crop yields. This study is noteworthy because it tackles the problems of nutrient imbalances, salinity, and acidity in the Nyarubogo irrigation system. This study aimed to assess the irrigation scheme's soil and water quality to spot any hazards to crop productivity and suggest suitable mitigation measures. A wide range of characteristics, such as pH, nutrient content, total dissolved solids (TDS), magnesium adsorption ratio (MAR), soluble sodium percentage (SSP), adsorption ratio (SAR), and electrical conductivity (EC), were determined on a comprehensive set of soil and water samples. The results showed that, with pH values ranging from 5.1 to 6.9, most of the soils in the study area are acidic, which may hinder crop development and nutrient availability. Furthermore, the soil demonstrated a moderate cation exchange capacity (CEC), suggesting a respectable ability to retain nutrients. The SAR of the water samples in this study ranged from 0.22 to 0.28 meq/l, indicating that water was suitable for irrigation and that no adverse effects were anticipated. It is evident from the high MAR values found in irrigation water that cautious management is required to avoid long- term soil deterioration. To lessen the negative consequences of acidity, salinity, and nutrient imbalances, this research emphasizes the need to routinely monitor the soil and water and use specific soil management techniques. The findings establish a basis for enhancing soil health and maintaining agricultural output, giving farmers and agricultural managers involved in the Nyarubogo irrigation project crucial information

Performance of conservation agriculture practices on the physical growth and yield of broccoli (Brassica oleracea L. var. italica) in Nyabihu District

Fri, 20 Sep 2024 00:00:00 +0000

This study aims to investigate the effect of various tillage methods on physical growth and yield of broccoli (Brassica oleracea L. var. italica). The experiment was conducted in farmers’field during seasons 2022B (March-June) and 2023A (September-February). Experiment was laid out in a Randomized Complete Block Design (RCBD) in Nyabihu District in four replications and five treatments which were T1(Conventional tillage), T2(zero tillage), T3(minimum tillage), T4(medium tillage) and T5(maximum tillage). Data were collected on physical growth at 15 days after planting (DAP) with interval of 15 days up to 45 DAP, while yield data were collected after harvesting. The Analysis of variance (ANOVA) was done following OPSTAT, statistical analysis tool, at P<0.05 and Least Significant Difference (LSD) was used for mean separation. There was a significant difference in physical growth and yield of broccoli. Minimum tillage outperformed other treatments both in growth and yield while zero tillage was the least. Yield was the highest with 31.32t/ha for minimum tillage and the lowest for maximum tillage with 10.18t/ha both in 2023A.Yield increment was highest for minimum tillage and lowest for zero and maximum tillage. Minimum tillage is advised to increase yield of broccoli and environmental conservation.