The experiment was conducted from March to July 2023 in Fokoué Subdivision, Menoua Division, Western Region of Cameroon. This area lies within the Western Highlands agro-ecological zone, characterized by volcanic soils, relatively mild temperatures, and high rainfall. The geographical coordinates range between 5˚16'N-5˚25'N and 10˚15'E-10˚30'E, with an average elevation of 1500 meters above sea level. The region experiences a bimodal rainfall pattern, with peaks in April-June and August-October, and annual precipitation between 1800 and 2000 mm. The mean annual temperature ranges from 20˚C to 24˚C. The predominant soil types are Andosols and Ferralsols, which are well-drained and fertile but susceptible to erosion on slopes [8] [9] .

The experiment was conducted using a Randomized Complete Block Design (RCBD) comprising three treatments, each replicated three times, resulting in a total of nine plots. Each plot measured 12 meters by 5 meters (60 m²), with 1-meter alleys separating plots and blocks to minimize edge effects and facilitate farm operations.

The treatments were as follows:

Land was manually cleared using machetes and hoes. Ridges were constructed 75 cm apart. For the agroforestry system, Gliricidia sepium stakes of approximately 1.5 meters in length were planted along the ridges at 2 m inter-row and 1.5 m intra-row spacing two months prior to potato planting to ensure sufficient biomass production for initial pruning. These hedgerows ran perpendicular to the slope to reduce erosion.

Seed tubers of the improved variety “Cipira” were sourced from the Institute of Agricultural Research for Development (IRAD) in Dschang. Tubers were cut into 40 - 60 g pieces with at least one viable eye and treated with wood ash to prevent fungal infections. Tubers were planted manually at a spacing of 30 cm within rows, resulting in 120 plants per plot.

The management of Gliricidia hedgerows was standardized to ensure consistency across plots. Stakes were initially planted two months before potato planting. Pruning was carried out every two weeks during the potato growth cycle, maintaining hedgerow height at approximately 1.0 - 1.2 meters. This allowed sufficient light penetration and regular biomass supply for green manure application.

All treatments were manually weeded at 15, 35, and 55 DAP using hoes. No irrigation was applied; the crop depended entirely on rainfall.

Growth parameters were recorded at 34, 48, 62 and 76 DAP using 10 randomly selected and tagged plants per plot:

At maturity (90 - 110 DAP), the following were recorded:

Yields were converted to tons per hectare (t/ha) for comparison using the formula:

$\text{Yield}\left(\frac{\text{t}}{\text{ha}}\right)=\left(\frac{\text{Yield per plot}\left(\text{kg}\right)\times 10000}{\text{Plot area}\left({\text{m}}^{\text{2}}\right)}\right)÷1000$ (1)

Scouting for pests and diseases began at 30 DAP and was conducted weekly until harvest. Each plot was assessed using the International Potato Center (CIP) [10] Visual Rating Scale (0 - 5):

Visual inspection and hand lens identification were used to monitor for:

The severity scores (0 - 5) were converted into severity indices following the CIP Visual Rating Scale using the formula:

$\begin{array}{l}\text{Pest Severity Index}\\ =\frac{{\displaystyle \sum \left(\text{Rating}\times \text{Number of plants at that rating}\right)}}{\text{Total number of plants observed}\times \text{Maximum rating scale of 5}}\end{array}$ (2)

An economic evaluation was conducted to assess the profitability of each cropping system. Total production cost (CP) was calculated by summing all variable costs associated with the production process, including the costs of seeds, fertilizers (organic and chemical), phytosanitary products (insecticides and fungicides), labor (for land preparation, ridging, input application, harvesting, and packaging), and transportation of inputs and harvested produce.

Interest on investment (II) was calculated as 10% of the total production cost, reflecting the opportunity cost of capital and risk associated with production activities, using the formula:

$\text{II}=\text{CP}\times 10\%$ (3)

The 10% interest rate reflects local credit interest rates for smallholder farmers in Cameroon during the study period, incorporating both opportunity cost and production risk. The market price of 14,000 FCFA per 50 kg bag was based on the prevailing average farm-gate prices during the cropping season, gathered from local markets in Menoua Division.

The market price (MP) was computed as the sum of the total production cost and interest on investment:

$\text{MP}=\text{CP}+\text{II}$ (4)

Sales of yield (SOY) were determined by multiplying the total marketable yield, expressed in number of 50 kg bags, by the prevailing local market price per bag, which was 14,000 FCFA:

$\text{SOY}=\text{Number of 50 kg bags}\times 14000\text{FCFA}$ (5)

The profit for each system was calculated as the difference between the sales revenue and market price:

$\text{Profit}=\text{SOY}-\text{MP}$ (6)

Profitability was expressed as a percentage, calculated by dividing the profit by the market price and multiplying by 100:

$\text{Profitability}\left(\%\right)=\frac{\text{Profit}}{\text{MP}}\times 100$ (7)

The value-cost ratio (VCR), which measures the return on each unit of currency invested, was calculated as:

$\text{VCR}=\frac{\text{SOY}}{\text{CP}}$ (8)

This profitability assessment was applied to all three production systems: the Agroforestry System (AFS), Conventional System (CS), and Control Plot (CP). All monetary values were expressed in FCFA (Central African CFA franc).

Data were analyzed using R version 4.2.2. A Shapiro-Wilk test checked for normality, and Levene’s test assessed homogeneity of variance. Parametric variables were subjected to One-way ANOVA, and significant differences were further tested using Tukey’s HSD at α = 0.05. Non-parametric data (e.g. pest severity scores) were analyzed using the Kruskal-Wallis H test, with pairwise comparisons using the Dunn test. Data visualization was performed with the ggplot2 and dplyr packages.

Prior to the implementation of the experiment, the chemical properties of the soils in the agroforestry and conventional plots were analyzed to determine baseline fertility conditions ( Table 1 ).

The pH of the agroforestry soil was moderately acidic (pH_h2o = 5.8; pHₖCl = 4.7), while the conventional plot exhibited slightly less acidity (pH_h2o = 6.2; pHₖCl = 5.0). Organic matter content (MO) was higher in the agroforestry system at 5.19%, compared to 4.3% in the conventional plot. Similarly, the carbon content (CO) was 3.01% in the agroforestry plot and 2.5% in the conventional plot. However, total nitrogen (N) content was notably higher in the conventional soil (0.125%) than in the agroforestry system (0.063%), reflecting potentially greater nutrient reserves from past chemical inputs.

Source: Soil Analysis and Environmental Chemistry Research Unit, FASA UDS, 2024.

The carbon-to-nitrogen (C/N) ratio was considerably higher in the agroforestry soil (48) than in the conventional soil (20), suggesting a higher amount of organic residue that could mineralize more slowly, hence supporting long-term soil fertility. In terms of exchangeable bases, calcium (Ca²⁺) was slightly higher in the conventional soil (3.12 meq/100g) than in the agroforestry system (2.72 meq/100g). Magnesium (Mg²⁺), potassium (K⁺), and sodium (Na⁺) concentrations followed a similar pattern, with higher values in the conventional soil: Mg²⁺ = 1.2 vs. 1.04 meq/100g; K⁺ = 1.5 vs. 0.83 meq/100g; Na⁺ = 0.29 vs. 0.22 meq/100g for conventional and agroforestry soils, respectively.

The sum of base exchange (SBE) was 5.84 meq/100g for the conventional system and 4.61 meq/100g for the agroforestry system. Cation exchange capacity (CEC), which reflects the soil’s ability to hold nutrients, was slightly higher in the agroforestry system (14.25 meq/100g) compared to the conventional system (13.75 meq/100g), indicating better potential for nutrient retention despite lower base saturation. Base saturation percentage (V%) was considerably higher in the conventional soil (42.47%) than in the agroforestry soil (32.36%). Finally, the concentration of available phosphorus (P) was 17.66 mg/kg in the conventional soil and 12.22 mg/kg in the agroforestry soil, indicating a richer phosphorus status in the former.

Overall, the conventional soil exhibited higher immediate nutrient availability, particularly for nitrogen, potassium, calcium, and phosphorus, while the agroforestry system showed higher organic matter content and a more favorable CEC, suggesting better long-term fertility sustainability.

The chemical analysis of Gliricidia sepium leaf biomass revealed its potential as a valuable organic amendment ( Table 2 ). The results showed that the dry biomass contained: Nitrogen (N): 3.72%, Phosphorus (P): 0.62%, Potassium (K): 2.27% and Organic matter (OM): 7.745%. These nutrient concentrations translate to substantial quantities of plant-available elements when biomass is applied to soil at field scale. Based on an average application rate of approximately 10.55 tons of fresh biomass per hectare, the corresponding fertilizing element contributions were estimated as follows: Nitrogen (N): 82.27 kg/ha, Phosphorus (P): 13.71 kg/ha, Potassium (K): 50.20 kg/ha Organic matter: 1712.85 kg/ha (approximately 1.71 tons/ha of organic matter). These figures demonstrate that Gliricidia sepium can serve as a low-cost and sustainable source of macro-nutrients, especially nitrogen and potassium, which are vital for vegetative growth and tuber development in potato. Its high organic matter content also contributes to improved soil structure, moisture retention, and microbial activity. The biomass thus plays a dual role—providing nutrients and enhancing long-term soil fertility.

Prior to potato planting, Gliricidia sepium prunings were applied as green manure in the agroforestry plots. The average biomass production per tree was 5.38 kg of fresh biomass, which upon drying yielded 1.538 kg of dry biomass. When extrapolated to field scale, the fresh biomass contribution was estimated at 10,552.61 kg per hectare (10.55 t/ha), which corresponded to 3,165.62 kg per hectare (3.17 t/ha) of dry matter ( Table 3 ).

The crown diameter, representing stem thickness at the base of the plant, was used as a key indicator of vegetative vigor across different cropping systems. Measurements were taken at 34, 48, 62, and 76 days after planting (DAP), and the results revealed significant differences among the cropping strategies ( Table 4 ).

AFS: Corridor agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p <0.01; ***p <0.001; ns: Not significant.

At 34 DAP, no significant difference was observed between the corridor agroforestry system (AFS) and the conventional system (CS) (Difference value = −0.65 ± 0.34 mm; p = 0.065), indicating a similar early-stage growth response. However, the crown diameter in AFS was significantly greater than in the control plot (CP) by 1.20 ± 0.34 mm (p = 0.001), while CS significantly outperformed CP by 1.85 ± 0.34 mm (p < 0.001). Combined, both AFS and CS significantly outperformed CP at this stage (contrast = 3.05 ± 0.34 mm; p < 0.001).

By 48 DAP, clear distinctions were established among the systems. CS had a significantly greater crown diameter than AFS (−1.07 ± 0.36 mm; p = 0.004), and both systems again significantly outperformed CP (AFS vs CP = 1.00 ± 0.36 mm; CS vs CP = 2.07 ± 0.36 mm; p < 0.01 for both). The combined contrast of AFS and CS versus CP was 3.08 ± 0.62 mm (p < 0.001), reflecting substantial improvements in stem development under fertilized or organically enriched conditions.

At 62 DAP, crown diameter continued to favor CS over AFS (−0.94 ± 0.39 mm; p = 0.019). AFS significantly outperformed CP by 1.50 ± 0.39 mm (p < 0.001), and CS exceeded CP by 2.44 ± 0.39 mm (p < 0.001). The cumulative contrast of AFS and CS over CP was 3.94 ± 0.68 mm (p < 0.001), showing sustained superiority of managed systems in enhancing stem robustness.

By 76 DAP, CS still had a significantly higher crown diameter than AFS (−1.54 ± 0.41 mm; p < 0.001), while AFS significantly outperformed CP by 1.50 ± 0.33 mm (p < 0.001). The difference between CS and CP was even greater at 3.04 ± 0.45 mm (p < 0.001). Overall, AFS and CS together showed a 4.54 ± 0.65 mm advantage over CP (p < 0.001), highlighting the compounding benefits of nutrient input and integrated soil fertility management.

Plant height differed significantly across the three cropping systems—corridor agroforestry system (AFS), conventional system with fertilizer (CS), and the control plot (CP)—over the course of the growing season, measured at 34, 48, 62, and 76 days after sowing (DAS) ( Table 5 ).

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p <0.01; ***p <0.001; ns: Not significant.

At 34 DAS, plant height in the CS system was significantly greater than in both AFS and CP. The difference between CS and CP was 10.83 ± 2.10 cm (p < 0.001), while AFS also exceeded CP by 4.67 ± 2.10 cm (p = 0.030). However, CS significantly outperformed AFS by 6.17 ± 2.10 cm (p = 0.005), indicating that early vegetative growth was more pronounced in the fertilized conventional plots than in the agroforestry system, where nutrient release from biomass was likely slower.

By 48 DAS, the disparity among treatments became more evident. CS plants remained significantly taller than those in AFS, with a mean difference of 9.17 ± 2.19 cm (p < 0.001). AFS continued to maintain a significant lead over CP, registering a 10.92 ± 2.19 cm advantage (p < 0.001). The CS plants were 20.08 ± 2.19 cm taller than those in CP (p < 0.001), and the combined effect of AFS and CS compared to CP was highly significant, with a cumulative difference of 31.00 ± 3.80 cm (p < 0.001). This reflects the compounding influence of both organic and inorganic nutrient inputs on vegetative development during mid-growth.

Interestingly, at 62 DAS, plant heights in AFS and CS were statistically equivalent (p = 1.000), both systems producing an identical increase of 31.06 ± 2.89 cm over CP (p < 0.001). This suggests that the nutrient release from Gliricidia sepium biomass in the AFS system had fully taken effect by this stage, resulting in vegetative performance comparable to that observed under chemical fertilization. The combined effect of AFS and CS relative to CP reached 62.11 ± 5.02 cm (p < 0.001), marking a significant divergence in growth performance from the control.

At 76 DAS, CS once again demonstrated superior plant height, surpassing AFS by 12.42 ± 4.20 cm (p = 0.001), likely due to the sustained availability of nitrogen from mineral fertilizers. Despite this, AFS maintained a strong advantage over CP, with a difference of 40.92 ± 3.79 cm (p < 0.001), while CS was 28.50 ± 3.06 cm taller than CP (p < 0.001). The joint comparison of AFS and CS with CP revealed a highly significant combined difference of 69.42 ± 5.46 cm (p < 0.001), confirming the overall positive influence of nutrient input—regardless of source—on final plant height.

These results demonstrate that while chemical fertilizers in the CS treatment provided a quicker and more sustained boost to plant height, the agroforestry system (AFS) was able to match and even approach the same level of vegetative performance at mid-season due to the delayed but effective nutrient release from Gliricidia sepium biomass. The control system consistently underperformed across all stages, reflecting the negative impact of nutrient deficiency on potato growth.

The number of lateral branches per plant, an important morphological trait linked to canopy development and potential yield formation, showed variable responses to cropping systems across the different days after sowing (DAS) ( Table 6 ).

At 34 DAS, there were no statistically significant differences among the three systems. The difference between AFS and CS was −0.62 ± 0.74 (p = 0.470), between AFS and CP was 0.17 ± 0.74 (p = 0.794), and between CS and CP was 0.79 ± 0.74 (p = 0.285). Even the combined effect of AFS and CS compared to CP was not statistically significant (p = 0.371), indicating that early branching was not influenced by treatment at this stage.

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p <0.01; ***p <0.001; ns: Not significant.

However, by 48 DAS, a significant difference emerged between AFS and CS, with the conventional system recording a higher number of lateral branches than the agroforestry system, as shown by a difference of −3.62 ± 1.17 (p = 0.030). AFS and CP remained statistically similar (p = 0.179), while CS significantly outperformed CP by 2.33 ± 0.87 branches (p = 0.012). The combined contrast of AFS and CS versus CP was still not statistically significant (p = 0.468), suggesting that although CS clearly promoted branching, the overall combined treatment effect had not yet differentiated enough from the control.

A more distinct pattern developed at 62 DAS. The number of lateral branches in the CS system was significantly greater than in both AFS and CP. The difference between AFS and CS reached −9.75 ± 4.09 (p = 0.024), indicating a strong advantage of the fertilized conventional system over agroforestry in terms of lateral shoot production. AFS, however, significantly exceeded CP by 6.46 ± 1.30 branches (p < 0.001), and CS was 16.20 ± 3.94 branches ahead of CP (p < 0.001). These trends were reinforced by the combined contrast between AFS and CS versus CP, which showed a highly significant difference of 22.67 ± 4.21 (p < 0.001).

At 76 DAS, the trend continued, though with some leveling off between the two managed systems. The AFS and CS systems did not differ significantly in branch number (difference = −0.96 ± 1.83; p = 0.603). However, AFS maintained a significant lead over CP by 4.08 ± 1.21 branches (p = 0.002), and CS was marginally higher than CP with a difference of 3.12 ± 1.56 (p = 0.055), bordering statistical significance. The combined comparison of AFS and CS with CP was again highly significant, with a mean difference of 7.21 ± 2.11 (p = 0.001), suggesting that both cropping systems contributed meaningfully to enhanced branching at the end of the vegetative stage.

Leaf area expansion, a critical determinant of photosynthetic capacity and overall biomass accumulation, varied significantly among the three cropping systems—corridor agroforestry system (AFS), conventional system with fertilizer (CS), and the control plot (CP)—across the growth stages evaluated at 34, 48, 62, and 76 days after sowing (DAS) ( Table 7 ).

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p <0.01; ***p <0.001; ns: Not significant.

At 34 DAS, the CS system recorded significantly higher leaf area compared to CP, with a mean difference of 104.17 ± 29.47 cm² (p = 0.002). AFS also exhibited a modest increase over CP (29.17 ± 19.94 cm²), although the difference was not statistically significant (p = 0.145). However, when compared directly with CS, the AFS system showed significantly lower leaf area, with a reduction of 75.00 ± 33.85 cm² (p = 0.033). The combined comparison of AFS and CS with CP revealed a cumulative difference of 133.33 ± 37.25 cm² (p = 0.001), confirming the early influence of input-based systems on leaf surface development.

By 48 DAS, CS maintained its superiority, with significantly greater leaf area than AFS by 266.67 ± 46.36 cm² (p < 0.001). AFS, in turn, significantly exceeded CP by 79.17 ± 29.47 cm² (p = 0.011), while CS was 345.83 ± 39.92 cm² ahead of CP (p < 0.001). The cumulative contrast between AFS and CS versus CP was highly significant at 425.00 ± 52.67 cm² (p < 0.001), showing a compounding advantage in leaf development in the nutrient-enriched systems.

At 62 DAS, the difference between CS and AFS widened further. CS produced 295.83 ± 56.70 cm² more leaf area than AFS (p < 0.001). AFS still retained a significant advantage over CP, with a difference of 233.33 ± 35.18 cm² (p < 0.001), while CS produced a much larger increase over CP, with a mean difference of 529.17 ± 49.05 cm² (p < 0.001). The combination of AFS and CS systems produced 762.50 ± 63.81 cm² more leaf area than CP (p < 0.001), clearly demonstrating the positive impact of both organic and inorganic nutrient inputs on canopy expansion.

At 76 DAS, leaf area in AFS and CS systems remained significantly higher than in CP. Although the direct comparison between AFS and CS was not statistically significant at this stage (−33.33 ± 61.29 cm²; p = 0.589), AFS maintained a strong advantage over CP with a difference of 529.17 ± 43.40 cm² (p < 0.001), and CS also maintained superiority over CP by 495.93 ± 49.50 cm² (p < 0.001). The combined effect of AFS and CS versus CP reached a peak cumulative difference of 1025.00 ± 70.09 cm² (p < 0.001), indicating that leaf area benefits were maximized late in the growth cycle in nutrient-supported systems.

The average yield of potato tubers differed significantly among the three production systems: the agroforestry system (AFS), the conventional system with chemical inputs (CS), and the traditional control system without any inputs (CP). As illustrated in Figure 1 , the highest yield was recorded under the conventional system (CS), with an average of approximately 40 tons per hectare, followed by the agroforestry system (AFS) with about 25 tons per hectare, while the lowest yield was observed in the control system (CP), which produced only around 10 tons per hectare.

Statistical grouping based on post hoc comparisons (indicated by different letters above the bars) showed that the yield in CS was significantly higher than that of both AFS and CP (p < 0.05). The AFS system also yielded significantly more than the CP system, confirming the beneficial effect of organic nutrient input from Gliricidia sepium biomass.

The number of tubers per plant showed significant variation among the different production systems. The conventional system with chemical inputs (CS) produced the highest tuber number per plant, followed by the agroforestry system (AFS), while the control system (CP) recorded the lowest performance ( Figure 2 ).

Under the CS system, the average number of tubers per plant reached approximately 17, which was significantly higher than the averages recorded in both AFS (8) and CP (4). The agroforestry system (AFS) produced an intermediate number of tubers per plant, averaging approximately 8 tubers, while the control system (CP) recorded the lowest tuber number, averaging approximately 4 tubers per plant. The differences among treatments were statistically significant, as indicated by the different letters assigned to each treatment group (a, b, and c), reflecting the results of multiple comparison tests at p < 0.05.

The evolution of downy mildew (Phytophthora infestans) severity varied significantly among the three cropping systems over the entire crop cycle, as shown in Figure 3 . Measurements were taken at 34, 48, 62, and 76 days after sowing (DAS) ( Figure 3 ).

At 34 DAS, no significant difference was observed in mildew severity between

the three systems, with severity remaining close to zero in all treatments. This suggests that initial disease pressure was low across the field, likely due to environmental conditions not yet favouring infection or pathogen development.

By 48 DAS, disease severity remained minimal for both the conventional system (CS) and the agroforestry system (AFS), while the control system (CP) exhibited a slight increase, although differences were not yet statistically significant at this stage.

At 62 DAS, the first marked differences in disease severity were observed. The control system (CP) recorded the highest severity score of approximately 1.15, while both CS and AFS remained zero, indicating effective disease suppression under both managed systems.

At 76 DAS, disease pressure increased further, and significant differences emerged between the treatments. The agroforestry system (AFS) exhibited the highest mildew severity, reaching a score of 0.75. In contrast, the conventional system (CS) recorded a lower severity score of 0.12, while the control plot (CP) maintained the lowest severity level (0.02).

The incidence of downy mildew also varied among the three cropping systems throughout the crop cycle. At 34 and 48 days after sowing (DAS), no incidence of downy mildew was recorded in any of the systems, indicating that the disease only became established during the later stages of the crop development ( Figure 4 ).

At 62 DAS, the first incidences of downy mildew were observed. The control system (CP) recorded the highest incidence, reaching a value of 0.92, while both the agroforestry system (AFS) and the conventional system (CS) maintained complete absence of disease at this stage (0 incidence for both). This reflects the early protective role provided by both chemical control in CS and the microclimatic or ecological benefits of the agroforestry system.

By 76 DAS, incidence increased further in the control system, reaching a peak value of 1.0. In contrast, the incidence in the CS and AFS systems remained substantially lower, with CS recording 0.33 and AFS recording 0.17.

At 76 days after sowing (DAS), detailed pairwise statistical comparisons of downy mildew severity and incidence across the cropping systems further confirmed the differential performance of the production strategies in managing disease ( Table 8 ).

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. **p < 0.01; ***p < 0.001; ns: Not significant.

For severity of downy mildew, the comparison between AFS (corridor agroforestry system) and CS (conventional system with fertilizer) revealed no statistically significant difference (difference = 0.02 ± 0.06; p = 0.001), indicating that both systems performed similarly in suppressing disease severity at this stage. However, both AFS and CS exhibited significantly lower severity compared to the control system (CP). The severity difference between AFS and CP was −0.51 ± 0.08 (p < 0.001), while the difference between CS and CP was −0.53 ± 0.07 (p < 0.001). The combined effect of AFS and CS compared to CP produced a highly significant cumulative difference of −1.04 ± 0.14 (p < 0.001), confirming that both management strategies substantially reduced disease severity relative to the untreated control.

For incidence of downy mildew, similar trends were observed. There was no significant difference between AFS and CS (difference = −0.17 ± 0.12; p = 0.230), suggesting that both systems offered comparable levels of disease prevention in terms of infection occurrence. However, AFS significantly outperformed CP by −0.83 ± 0.08 (p = 0.010), and CS also significantly outperformed CP by −0.67 ± 0.08 (p = 0.015). The combined AFS and CS treatments differed from CP by −1.50 ± 0.12 (p < 0.001), confirming strong suppression of infection in both managed systems relative to the control.

The incidence of leaf-eating caterpillars exhibited considerable variation among the three production systems throughout the growing period, as shown in Figure 5 . Observations were recorded at 34, 48, 62, and 76 days after sowing (DAS) ( Figure 5 ).

At 34 DAS, leaf-eating caterpillars were only detected in the conventional system with chemical inputs (SC), which recorded an initial incidence of 0.33. In contrast, no incidence was recorded in either the agroforestry system (SAF) or the control system (CP) at this early stage.

By 48 DAS, pest incidence increased across all systems but remained most pronounced in the SC system, which recorded an incidence of 0.58. The control system (CP) exhibited a lower incidence of 0.41, while the SAF system continued to suppress caterpillar infestation effectively, maintaining an incidence of zero. This suggests that the organic mulch and microclimatic buffering in the agroforestry system may have provided early-season protection against pest colonization.

At 62 DAS, the incidence reached its peak in the SC system, recording the highest value of 0.83. The SAF system recorded an increase to 0.75, while CP remained lower at 0.41. The sharp increase in caterpillar presence in SAF at this stage may reflect seasonal pest pressure combined with maturing plant tissue that is more attractive to larval feeding.

By 76 DAS, pest incidence declined in both SAF and SC but increased slightly in CP. The SC system recorded the highest final incidence at 0.91, followed by SAF at 0.75, while CP reached 0.33. These results indicate that even under chemical control, SC did not fully suppress caterpillar infestation, while the agroforestry system continued to provide relatively better control compared to the untreated control.

The severity of damage caused by leaf-eating caterpillars varied across the three cropping systems throughout the growing cycle, as illustrated in Figure 6 . Measurements were taken at 34, 48, 62, and 76 days after sowing (DAS).

At 34 DAS, caterpillar severity was minimal across all systems. The conventional system (CS) recorded a low severity score of 0.083, while both the agroforestry system (AFS) and the control system (CP) recorded zero severity, indicating no noticeable damage at this early stage.

By 48 DAS, pest severity began to rise in the CS system, reaching 0.12, while both AFS and CP continued to record zero severity. This suggests that early in the crop cycle, Gliricidia sepium hedgerows may have helped suppress initial pest establishment in the agroforestry system, while the control system still remained unaffected.

At 62 DAS, both AFS and CP started to experience caterpillar damage. CS recorded the highest severity of 0.29, followed by AFS at 0.20, and CP at 0.14. This shift reflects the mid-season escalation of pest pressure across systems as leaf canopy expansion provided increased feeding surface.

By 76 DAS, pest severity reached its maximum levels in all systems. CS recorded the highest severity of 0.38, closely followed by CP at 0.35. In contrast, AFS recorded the lowest severity of 0.14, highlighting the sustained capacity of the agroforestry system to suppress pest severity even under increased seasonal pest pressure.

At 76 days after sowing (DAS), the incidence and severity of leaf-eating caterpillars were statistically compared across the three cropping systems: corridor agroforestry system (AFS), conventional system with fertilizer (CS), and the control system (CP) ( Table 9 ).

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p < 0.01; ns: Not significant.

For incidence of leaf-eating caterpillars, the incidence in AFS was significantly lower than in CS, with a difference of −0.58 ± 0.15 (p = 0.009). Similarly, AFS recorded significantly lower incidence compared to CP, with a difference of −0.42 ± 0.15 (p = 0.034). However, there was no significant difference between CS and CP for incidence (difference = −0.17 ± 0.15; p = 0.315), indicating that chemical fertilization did not significantly reduce pest incidence relative to the untreated control system. The combined comparison between AFS and CS versus CP was not significant either (difference = −0.25 ± 0.26; p = 0.379), suggesting variability in pest incidence across the systems when considered together.

For severity of leaf-eating caterpillars, a similar trend was observed. AFS demonstrated significantly lower severity compared to CS (difference = −0.24 ± 0.09; p = 0.016), and significantly lower severity compared to CP (difference = −0.21 ± 0.09; p = 0.033). The difference between CS and CP was not significant (difference = −0.03 ± 0.09; p = 0.757), confirming that chemical treatment did not confer an advantage over the control in reducing caterpillar damage severity. The combined AFS and CS vs CP comparison also remained non-significant (difference = −0.18 ± 0.12; p = 0.277).

The incidence of whitefly populations varied among the production systems over the entire crop cycle. Observations were taken at 34, 48, 62, and 76 days after sowing (DAS), with considerable fluctuations in pest pressure observed between the different systems and growth stages ( Figure 7 ).

At 34 DAS, whitefly incidence was relatively low in all systems. The agroforestry system (AFS) recorded the lowest incidence at 3.87 individuals per plant, while the conventional system with chemical inputs (CS) recorded 5.58, and the control system (CP) recorded 4.75. This suggests that early-season whitefly pressure was minimal but already slightly elevated in the CS system.

By 48 DAS, the incidence increased sharply, particularly in the CS system, which peaked at 8 individuals per plant. The control system (CP) followed with 5.87, while the AFS system recorded 5.58, indicating some moderate buildup of whitefly populations but with more effective suppression under agroforestry.

At 62 DAS, the whitefly population peaked in the CP system, reaching its maximum incidence of 8.08 individuals per plant. Meanwhile, both the CS and AFS systems recorded relatively lower incidences of 5.83 and 5.54, respectively. These results suggest that the absence of any control strategy in the CP system allowed for continuous buildup of whitefly populations, while both management systems were able to moderate population growth during this stage.

At 76 DAS, incidence in the CP system declined slightly to 7 individuals per plant, while CS recorded 6.87 and AFS recorded the lowest incidence at 5.04. By the end of the growing period, the agroforestry system consistently maintained lower whitefly populations compared to both the chemically managed and control systems.

The incidence of whitefly populations differed significantly between cropping systems at multiple stages of the crop cycle. The data presented in Table 10 provide a detailed pairwise comparison of these differences at 34, 48, 62, and 76 days after sowing (DAS).

At 34 DAS, a significant difference was observed between the agroforestry system (AFS) and the conventional system (CS), with AFS recording a lower incidence

AFS: Agroforestry system; CS: Conventional system; CP: Control plot. *p < 0.05; **p < 0.01; ***p < 0.001; ns: Not significant.

by −1.71 ± 0.50 (p = 0.003). However, no significant differences were found between AFS and the control system (CP) (p = 0.115), or between CS and CP (p = 0.052), suggesting that at this early stage, only the agroforestry system offered statistically lower whitefly incidence compared to chemical control, while the control and conventional systems exhibited similar incidence levels.

At 48 DAS, the differences between AFS and CS remained statistically significant, with AFS showing lower incidence by −2.00 ± 0.70 (p = 0.006). AFS vs CP remained non-significant (p = 0.681), while CS exhibited significantly higher whitefly incidence compared to CP by 1.71 ± 0.70 (p = 0.018). These results indicate that at mid-season, whitefly populations escalated more rapidly in the conventional system than in both agroforestry and control plots.

At 62 DAS, the pattern shifted. There was no significant difference between AFS and CS (p = 0.648), but AFS maintained significantly lower incidence compared to CP by −2.25 ± 0.64 (p < 0.001). The CS system also showed significantly higher incidence than CP by −2.54 ± 0.64 (p < 0.001), confirming that by 62 DAS, both managed systems (AFS and CS) controlled whitefly better than the control, but incidence levels between CS and AFS converged.

At 76 DAS, the difference between AFS and CS re-emerged as significant, with AFS recording a lower incidence by −2.00 ± 0.63 (p = 0.002). AFS also maintained a significantly lower incidence compared to CP by −1.83 ± 0.63 (p = 0.005), while the difference between CS and CP was non-significant (p = 0.793). The combined effect of AFS and CS compared to CP remained non-significant at this stage (p = 0.132).

The economic analysis revealed substantial differences in production costs, revenues, profits, and profitability indicators across the three cropping systems: Agroforestry System (AFS), Conventional System with chemical inputs (CS), and Control Plot (CP) ( Table 11 ).

The marketable yield was highest under the conventional system (CS) at 38.97

CP: Cost of production; MP: Market price; SOY: Sales of yield; II: Interest on investment; VCR: Value to cost ratio.

t/ha, followed by AFS with 25.42 t/ha, and the lowest yield recorded in CP at 10.53 t/ha. This yield performance directly translated into variations in both revenues and profitability across the systems.

The total production cost (CP) was highest in CS, amounting to 2,113,600 FCFA/ha due to the substantial cost of chemical fertilizers (280,000 FCFA/ha), phytosanitary products (insecticides and fungicides totaling 116,500 FCFA/ha), and additional labor costs for chemical application and input transportation. The production cost in AFS was lower at 1,624,750 FCFA/ha, while CP, which involved minimal input, recorded the lowest production cost of 534,000 FCFA/ha.

The total sales revenue (SOY) was highest under CS, reaching 10,911,600 FCFA/ha due to its superior yield. AFS achieved a sales revenue of 7,588,000 FCFA/ha, while CP produced the lowest revenue of 728,000 FCFA/ha.

When calculating profit, CS remained the most profitable, yielding 8,586,640 FCFA/ha. However, AFS also generated a strong profit of 5,501,575 FCFA/ha, while CP returned a minimal profit of 140,000 FCFA/ha, reflecting its limited productivity.

In terms of profitability ratios, the agroforestry system (AFS) achieved a profitability of 324.61% and a value-cost ratio (VCR) of 4.24. The conventional system (CS) recorded a slightly higher profitability of 369.32% and a VCR of 4.69. In contrast, the control system (CP) recorded a substantially lower profitability of only 23.83% and a VCR of 1.26.

Although the conventional system generated the highest absolute profit due to its superior yields, it also incurred the highest production costs. The agroforestry system, while yielding moderately lower production and revenues, exhibited a very competitive profitability ratio when considering its reduced input dependency and lower production costs. The control system, lacking both nutrient and pest management interventions, produced minimal financial returns and demonstrated poor profitability.

These findings suggest that the agroforestry system offers a highly promising economic alternative, delivering strong profitability while significantly reducing dependence on costly external inputs, making it a more sustainable and resilient option for resource-limited farmers.