Soybean is a food security crop in Benin due to its high nutritional value but its yield in the farmers’ cropping system is very low. The present study aims to provide appropriate response to the yield variability among fields in two agro-ecological zones of Benin namely: Southern Borgou zone (AEZ 3 in the north) and cotton zone of central Benin (AEZ 5). Soil samples were collected from 0-20 cm depth in 120 fields (50 in the AEZ 3 and 70 in the AEZ 5). pH (water), soil organic carbon (Walkley and Black method), total nitrogen (Kjeldahl method), CEC (0.01 N ammonium acetate at pH 7 method) and available phosphorus (Bray 1) were determined in the laboratory of Soil Science Water and Environment (LSSEE) of the National Agricultural Research Institute of Benin (INRAB). Cropping system (crop rotations, soil fertility management practices) were also collected using an open ended questionnaire. Classification and regression trees (CARTs) models were used for data analyses. Soybean yield variability among the agro-ecological zones were registered and the highest yield recorded was less than 1 t.ha^-1. Considering soil characteristics, soil organic matter level was the most important variable determining yield variability. Furthermore, quantities of P applied and farmyard manure were cropping practices inducing yield variability (86.4% and 15% of the variability respectively). Our results also show that, yield differences noticed among the agro-ecological zones were induced by CEC and pH (water). The study suggested promotion of integrated soil fertility management practices to sustain soybean yield in the study area.

Purpose: Cassava is an important root crop in maintaining food security for the population in the Republic of Centrafrique (CAR). Despite this socio-economic importance, yields obtained remain low and demands are not yet met. The aim of this study was to identify socio economic and management factors that determine cassava yields in two agroclimatic zones of CAR.Research Method: Socio-demographic characteristics, soil fertility management practices in cassava cropping systems and constraints related to cassava production in the CAR forest and savanna zones were collected using semi-structured interviews. Descriptive statistics, Student’s t test and ordinal logistic regression were used to analyze data collected.Findings: Cassava is the main crop in two agroclimatic zones. It is an activity carried out mainly by men. The areas sown for cassava vary between 0.45 and 0.85 ha. The main varieties grown were TMS 92/0329 (locally named Togo) and C96/OO5 (locally named Bobeketi). Disease resistance, high yield and organoleptic quality are the main criteria used for selecting varieties to grow. Cassava yields obtained for all varieties combined are significantly different (p = 0.0001) in the two zones, with an average of 4.41 t.ha-1 of root. These low yields were related to climatic constraints (violent wind and irregular rainfall) and a decline in soil fertility.Originality/ Value: It is proposed to implement integrated soil fertility management strategies by combining mineral and organic fertilizers available in climatic zones that optimize plants’ nutrient use efficiency in a context of climatic changes for sustainable cassava production.

Maize is vital for food systems and rural livelihoods in the Democratic Republic of Congo (DRC). Continuous cultivation depletes soil nutrients, reducing maize production. Inorganic (or mineral) fertilizers provide nutrients rapidly, but their cost and sustainability concerns have prompted interest in alternatives. Biological amendments improve nutrient uptake and soil structure and boost crop resistance, potentially cutting mineral fertilizer use. The present study aims to investigate the direct and residual effects of biological amendments (BAs) on maize productivity in the Eastern DRC, both when applied alone or combined with inorganic fertilizer, with trials conducted in the Kabare, Kalehe, and Ruzizi Plain regions from October 2022 to June 2024. Two trials across four seasons gathered data using a randomized complete block design (RCBD) with nine treatments and three replicates: Control, without fertilizer application; farmer practice; inorganic fertilizer (NPK 17-17-17 and urea); BA_1: Lactobacillus; BA_2: fish serum; BA_3: black soldier fly (BSF) compost; BA_1 + inorganic fertilizer; BA_2 + inorganic fertilizer; and BA_3 + inorganic fertilizer. The results identified three categories: integrated organic and inorganic fertilizers, single applications, and inconsistent uses. The best outcomes emerged from treatments combining Lactobacillus, fish serum, and BSF compost with inorganic fertilizer, positively impacting maize yield parameters. The study confirms that combining biological amendments and mineral fertilizers significantly (p < 0.001) enhances maize productivity in the Eastern DRC. Performance differences across locations emphasize the influence of local soil characteristics and targeted nutrient strategies.

Climate variability represents one of the major risk factors affecting groundnut and soybean production in Benin. Taking climate variability into account in the fertilizer recommendation process is important. The study aims to validate the CROPGRO model and estimate the yield responses of groundnut and soybean to simulated doses of N, P, K, Mg, and Zn for the 1980–2018 and 2018–2079 climate scenarios (RCP 4.5 and RCP 8.5). Climate data from the Decision Support System for Agrotechnology Transfer (DSSAT) and the Coordinated Regional Climate Downscaling Experiment-Africa framework (CORDEX) were used to simulate crop-yield responses in the Centre and the North of Benin. Two years of field trials (2018 and 2019) and the recorded optimal doses of N, P, K, Mg, and Zn doses determined (16-20.18-6.7-5.6-2.47 and 13.1-25.07-20-11.47-1.82 for groundnut and soybean in the Centre and the North, respectively and 14-23.9-18.18-11.45-4.14 and 16.6-23.5-29-15.2-7.7 for soybean in the Centre and the North, respectively) were considered. The CROPGRO model demonstrated strong accuracy in simulating the yields of both crops, with R2 values ranging from 0.76 to 0.96 and NRMSE values between 10.31% and 22.8%. Projected climate scenarios indicated a decline in crop yields (9% to 19%, RCP 4.5) and a decrease of 22% to 31% by mid-century. This study suggests a readjustment of N, P, K, Mg, and Zn application rates by the end of the century to ensure substantial groundnut and soybean production in Benin.