Biochar (B) has low nutrient content and is recalcitrant to biodegradation. Supplementing B with a fast-releasing nutrient source may improve soil fertility and physical conditions and increase crop productivity. A three-season field study was conducted on sandy loam and sandy clay loam textured soils to investigate the effect of B mixed with livestock manure (LM) on soil properties (pH, organic carbon (OC), cation exchange capacity (CEC), total Nitrogen (TN), available Phosphorus (Avail P)), and French bean yield (Phaseolus vulgaris L.) in Rwanda. The study used a factorial randomized block design with four replications. Treatments comprised three levels of B (0, 1, and 3 t/ha) and three levels of LM (0, 1, and 3 t/ha). Biochar was used from S. sesban, G. sepium, A. angustissima, Eucalyptus, and Grevillea sp., prepared using a drum kiln, while LM was prepared using the pit method. The Analysis of Variance (ANOVA), Tukey (HSD) function at p < 0.05, and linear mixed-effects model were performed in R software version 4.3.3 (R Core Team, 2024). The analysis showed that the treated plots significantly increased French bean yield compared to the control plots, with the highest value found in plots treated with 3 t/ha. The combined plots showed an increased yield compared to sole Biochar or manure. The seasonal increase has been observed, with percentage increases recorded as follows: 16%, 33.56%, 173.06% in sole B plots; 40.28%, 14.43%, and 11.76% in sole LM plots and 125%, 156%, and 209.8% in B + LM plots for season 1, 2, and 3, respectively. Furthermore, the results indicated that the application of B alone or combined with LM significantly enhanced soil pH, OC, TN, avail P, and CEC with the pH ranging from 6.77 to 5.43 for B alone, 6.7–5.35 for LM alone, 8.53–6.06 for B-LM plots, and 4.34–3.78 for control plots. Applying Biochar, either alone or in combination with LM, at a low rate demonstrated positive effects on French bean yield and soil nutrients in smallholder farmers. This study encourages using natural materials such as B and LM to improve soil fertility and increase vegetable production while reducing chemical fertilizers that can cause pollution and damage the environment.

Globally, multiple ecosystem services are increasingly becoming an important agenda in sustainable forest management. However, it is still unclear which forest management practices would lead to an optimal bundle of ecosystem services promoting sustainability. This study aimed to determine whether implementing thinning schedule and 30 years rotation age has implications on the provision of ecosystem services and economic benefits of Teak stands in Tanzania. Carbon quantification and cost-benefit analysis methods were used to study the climatic and economic benefits of wood production and carbon sequestration under five scenarios where three thinning schedules and 30 years rotation age were the baseline. Data were collected from 168 purposively selected circular plots of radius 9.78 m distributed systematically in 9 thinned stands. Thinned stands were implemented with intensities of 50%, 50%, and 25% in first, second, and third thinning respectively. Results showed that decreasing 33.4% rotation age from baseline while maintaining three thinning schedules maximized climatic and economic benefits of combined wood production and carbon storage goal by 181.5%. Preferred thinning schedules and rotation age had wood production and carbon sequestration of 821 m3/ha and 41.3 t/ha respectively. Managing Teak Forest plantation for the combined goal of wood production and carbon sequestration is recommended.

Entandrophragma bussei Harms ex Engl. (wooden banana) is an important indigenous multipurpose tree species endemic to Tanzania. The species has a long history of human use but recent increased utilization pressure, deforestation and high mortality rate of seedlings threaten the survival of natural populations in the wilderness. Therefore, to facilitate domestication, two experimental studies were conducted to evaluate variations in seed germination and seedling growth of three wild populations at the Directorate of Tree Seed Production Laboratories in Morogoro, Tanzania. Germination percentage, mean germination rate, final germination rate and germination index varied significantly among the populations. In terms of seedling growth there was a significant difference in number of leaves among the populations at 3 months of age. The number of course roots and seedling shoot fresh weight varied significantly among the studied populations at 10 months of age. Ruaha population had the highest survival (56%) followed by Kigwe (41%) and Tarangire being the last (36%). The two experiments have clearly demonstrated the existence of considerable variation in germination and seedling growth traits in E. bussei. These traits may prove to be important tools for selection of suitable seed sources for domestication and tree improvement programmes.

Biochar (B) in combination with organic manure could improve the biochar efficacity in improving soil functions related to hydrophysical properties. Short-term field experiments were conducted with three levels of B and livestock manure (LM) (0, 1, and 3 tons/hectare (t/ha)) to assess its effect on physical properties of soils such as bulk density (BD), soil porosity (SP) and aggregate stability (AS), along with soil hydro properties, including field capacity, permanent wilting point (PWP), Plant available water (PAW), and hydraulic conductivity (Ksat). Each treatment was replicated four times in a factorial randomised block design (RBD) using French beans as a test crop in sandy soils and sandy clay loam-textured soils in Rwanda. The data were analysed using analysis of variance (ANOVA) together with the Duncan test at P < 0.05 using R Studio. The findings demonstrated that the co-application of B and LM at varying application rates significantly (P < 0.05) reduced soil bulk density (BD), with the lowest BD observed at the highest application rate (3t/ha). Additionally, the results indicated that the combined application of B and LM at lower rates significantly affected soil water retention characteristics, including permanent wilting point (PWP), field capacity (FC), and saturated hydraulic conductivity (Ksat). The improvements in these properties became more pronounced with increasing B rates when mixed with LM. These results contribute to a better understanding of soil water dynamics following B and LM applications and suggest a promising approach to mitigating water loss, especially in sandy soils.