Soil organic carbon storage in agricultural soil constitutes a crucial potential for sustainable agricultural productivity and climate change mitigation. This paper aimed at assessing soil organic carbon stock and its distribution in three particle size fractions across five cropping systems located in Kiti sub-watershed in Benin. Soil samples were collected using a grid sampling method on four soil depth layers: 0–10, 10–20, 20–30 and 30–40 cm in five cropping systems maize–cotton relay cropping (MCRC), yam–maize intercropping (YMI), teak plantation (TP), 5-year fallow (5YF) and above 10-year fallow (Ab10YF) from July to August 2017. Soil organic carbon stock (C stock) was estimated for the different soil layers and particle-size fractionation of soil organic matter was performed considering three fractions. The fractions coarse particulate organic matter (cPOM: 250–2000 µm), fine particulate organic matter (fPOM: 53–250 µm) and non-particulate organic matter (NOM: <53 µm) were separated from two soil depth layers: 0–10 and 10–20 cm. The results showed that fallow lands Ab10YF and 5YF exhibited the highest C stock, 22.20 and 17.74 Mg C·ha⁻¹, while cultivated land under tillage MCRC depicted the lowest, C stock 11.48 Mg C·ha⁻¹. The three organic carbon fractions showed a significant variation across the cropping systems with the NOM fraction holding the largest contribution to total soil organic carbon for all the cropping systems, ranging between 3.40 and 7.99 g/kg. The cPOM and fPOM were the most influenced by cropping systems with the highest concentration observed in Ab10YF and 5YF. The findings provide insights for upscaling farm management practices towards sustainable agricultural systems with substantial potential for carbon sequestration and climate change mitigation.

Soil erosion has become one of the most common environmental problems and threatens food security. This study assessed the short‐term effect of tillage and mulch on soil redistribution using the beryllium‐7 method, soil moisture distribution, and soil organic carbon loss through soil erosion in typical agroecological conditions of Benin. The experiment was conducted on acrisols (at Dan) and ferralsols (at Za‐zounmè) in central Benin. Three tillage practices slope ridging (SR), contour ridging (CR), and no‐tillage (NT), and three mulch doses 0 (0 M), 3 (3 M), and 7 t ha⁻¹ (7 M) on soil erosion under maize were investigated. The results showed a tillage and mulch interaction significantly (p < 0.05) influencing the soil redistribution, the loss of total carbon, the carbon of the particulate organic matter (C_POM), and the carbon content of the fine organic matter (C_MOM). High soil erosion was observed under SR0M (−10.19 t ha⁻¹) at Dan and under NT0M (−7.36 t ha⁻¹) at Za‐zounmè. NT7M (0.80 t ha⁻¹), SR7M (0.69 t ha⁻¹), CR3M (2.07 t ha⁻¹), and CR7M (4.05 t ha⁻¹) showed deposition at Dan, while SR7M (0.23 t ha⁻¹), NT7M (1.69 t ha⁻¹), and CR7M (3.93 t ha⁻¹) showed deposition at Za‐zounmè. C_MOM was lost on both sites. Mulch increases soil moisture for all three tillage treatments, and this effect is well pronounced especially if the amount of mulch is great. This study revealed useful information to be taken into consideration when developing soil and water conservation management strategies in Benin.

To restore soils degraded by unsuitable practices, which have led to declines in organic matter content and associated consequences, sustainable land management (SLM) practices have been implemented in central Benin. This study aimed to evaluate the effects of these practices on soil organic matter (SOM) levels in cultivated soils in Central Benin. Soil samples were collected from a depth of 0 to 20 cm on SLM plots in two agricultural areas: N’Tchon and Odjobilè. The SLM practices studied were maize intercropped with pigeon pea ( Cajanus cajan ), mucuna ( Mucuna pruriens ), soybean ( Glycine max ), cowpea ( Vigna unguiculata ), groundnut ( Arachis hypogea ), aeschynomene ( Aeschynomene histrix ), and cassava ( Manihot esculenta ). For each SLM practice, adjacent control plots were sampled. Soil pH, cation exchange capacity (CEC), soil organic carbon (SOC), carbon organic stock (COS), and particulate organic carbon (POC) were measured. Compared to the adjacent control plots, the soybean–maize and aeschynomene–maize rotations significantly increased soil CEC ( p < 0.05). SOC differed significantly ( p < 0.05) among SLM practices, ranging from 0.37 to 1.67 g/kg. COS was higher with pigeon pea–maize intercropping (37.21 Mg C ha ⁻¹ ) in Odjobilè and with cassava–maize intercropping (37.46 Mg C ha ⁻¹ ) in N’Tchon. The contribution of coarse particulate organic carbon (cPOM‐C) to total particulate organic carbon (tPOM‐C) was smaller than that of fine particulate organic carbon. The greatest cPOM‐C was observed with cowpea–maize and pigeon pea–maize intercropping. However, the greatest fPOM‐C was observed with cowpea–maize intercropping in Odjobilè and with pigeon pea–maize intercropping in N’Tchon. Therefore, SLM practices, such as intercropping with pigeon peas and maize, can serve as an alternative to crop residue burning. These practices can help restore the fertility of degraded soils.

This study was conducted to assess effect of tillage and mulch on soil erosion control in typical agroecological conditions of Benin. In addition, it involved also the assessment of soil moisture and runoff. The experiment was conducted on two sites in Central Benin during the short rain season of 2018. The effect of three tillage practices (contour ridging: CR; slope ridging: SR and no-tillage: NT) and three mulch doses (0 t.ha-1; 3 t.ha-1; and 7 t.ha-1) on soil erosion under maize was investigated at small experimental plots (21 m2). The 7Be method was used to assess the erosion rates, runoff was measured by total collection and soil moisture content was determined by thermo-gravimetric method. The results showed a significant decrease in runoff coefficient and soil loss while increase soil moisture under no-tillage and contour ridges compared to slope ridges. This effect was pronounced with greatest. 3 and 7 tha-1. Highest runoff coefficient and soil loss and the lowest soil moisture were observed under slope ridging without mulch (i.e. SR0M). The 7Be measurement showed high soil losses under SR0M (-10.19 t ha-1) at Dan and under NT0M (-7.36 t ha-1) at Za-zounmè. The treatments NT7M (0.80 t ha-1); SR7M (0.69 t ha-1); IR3M (2.07 t ha-1) and CR7M (4.05 t ha-1) showed deposition at Dan while SR7M (0.23 t ha-1) and CR7M (3.93 t ha-1) showed deposition at Za-zounmè. This study revealed useful information to be taken into consideration when developing soil and water conservation management strategies in Benin.

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.