This research was conducted within the two principal irrigated rice-growing perimeters of Cameroon’s Sudano-Sahelian zone: the Yagoua zone, managed by the Société d’Expansion et de Modernisation de la Riziculture de Yagoua (SEMRY) in the Far North Region, and the Lagdo zone, developed under the Projet Hydro-Agricole de Lagdo (PHAL) in the North Region (Figure 1Figure 1). These sites were strategically selected for this investigation due to their paramount importance in the national rice production landscape, collectively representing the most extensive and historically significant areas of irrigated rice cultivation in the country [4][11].

Figure 1.Location map (Maralossou).

The Yagoua rice perimeter is situated in the Mayo-Danay Division, with its geographical coordinates spanning between 10˚0'0" and 11˚0'0" North latitude and 14˚40'0" and 15˚20'0" East longitude. This area is strategically positioned within a transboundary context, bordered to the north by the Logone and Chari Division, to the west by Mayo-Kani, to the east by the Republic of Chad, and to the south by the communes of Gobo, Guéré, and Wina [12]. Its location places it at the heart of a complex hydrological and agricultural system.

Conversely, the Lagdo rice perimeter is located in the Bénoué Division, extending between 8˚40'0" and 9˚20'0" North latitude and 13˚0'0" and 14˚60'0" East longitude. This irrigated scheme is enclosed by a constellation of municipalities, sharing its northern and western boundaries with Ngong and Bibémi, its southern limits with Tcholliré and Poli, and its eastern frontier with Rey Bouba and Bibémi [13]. The presence of the Lagdo dam on the Bénoué River is a critical feature of this site, providing the essential water resources that underpin its hydro-agricultural operations.

2.2.1. Determining the Optimal Sample size

To establish a statistically representative sample for this study, the sample size was calculated a priori using the standard formula for estimating a population proportion with a specified confidence level and margin of error [14][15]. This calculation is essential for ensuring the precision of the survey findings and the validity of generalizations drawn from the sample. The formula is applied as follows:

The variables are defined as: n: The minimum sample size required; t: The z-value for the desired confidence level (1.96 for a 95% confidence level); p: The estimated prevalence of the characteristic of interest within the population. A proportion (p) of 0.5 was selected, as this maximizes the sample size and provides the most conservative estimate in the absence of previous studies; e: The desired margin of error (precision), set at ±5% (0.05).

The application of Schwartz’s formula (1995) with a 95% confidence level (t = 1.96) and a 5% margin of error (e = 0.05) yielded specific sample sizes for each study site. The calculation incorporated the known proportion (p) of rice farmers relative to the total agricultural workforce in each area, which was 0.1894 for Lagdo and 0.3582 for Yagoua. This resulted in minimum sample sizes of 236 and 353 farmers for Lagdo and Yagoua, respectively, leading to a total sample of N = 589.

To ensure the data’s relevance and quality, a purposive sampling strategy was employed. This "reasoned choice" technique involved deliberately selecting participants who were active rice farmers with substantial practical experience, thereby ensuring that the respondents possessed the direct knowledge necessary to inform the study’s objectives [16].

2.2.2. Choice of Study Villages

The survey respondents were strategically selected from six villages that serve as major hubs for irrigated rice production within the Lagdo and Yagoua perimeters. As presented in Table 1, the sample distribution reflected the relative scale of rice cultivation in each locality. In total, 40.07% of respondents (n = 236) were surveyed across three villages in the Lagdo zone: Gounougou (13.24%), Ouro Doukoudje (14.09%), and Bessoum (12.73%). The remaining 59.93% (n = 353) were surveyed in the Yagoua zone, specifically in the villages of Vele (20.20%), Kartoua (21.05%), and Gabaraye Widi (18.68%).

Table 1. Survey methodology.

To ensure the data reflected a multi-tiered understanding of the rice production system, a diverse cohort of stakeholders was purposively selected for interviews. The participant pool comprised not only active rice farmers but also key institutional actors. This included agricultural production managers, presidents of Water User Associations (AUE), management staff from SEMRY and PHAL, and technical representatives from pertinent government ministries (MINADER, MINEE, MINEPDED, MINFOF, MINSANTE). This methodological approach, which integrates grassroots and institutional perspectives, is well-supported in the literature [17][18].

A mixed-methods approach centered on field surveys was employed to assess the environmental impact of rice farming in the Sudano-Sahelian zone. Primary data were collected through a combination of semi-structured and structured interviews, facilitated by a comprehensive questionnaire specifically designed for this study. The instrument incorporated a blend of closed-ended (yes/no), open-ended, and multiple-choice (guided) questions to capture both quantitative data and nuanced qualitative perspectives [19].

The questionnaire was organized into four thematic sections: rice farming practices, levels of rice field degradation, importance and expansion of rice cultivation, and adverse environmental effects.

Rice farming practices

Documenting production methods (suitable soil types, plot cleaning, plowing techniques, rice varieties, sowing types) and maintenance practices (fertilization, weed, pest, and disease control, and harvesting methods).

Levels of rice field degradation

Investigating causes of soil degradation and water pollution, tracking changes in soil fertility, input usage on 0.5-hectare plots, and yields over the past decade, and documenting the consequences of productivity decline.

Importance and expansion of rice cultivation

Examining the socio-economic role of rice and historical changes in land use since the development of the irrigation perimeters.

Adverse environmental effects

Identifying the perceived negative impacts of rice cultivation on the local ecosystem.

To triangulate and validate the self-reported data, post-interview field visits and direct observations were conducted in the rice fields of both Lagdo (PHAL) and Yagoua (SEMRY).

All collected data were systematically entered into a Microsoft Excel 2016 spreadsheet for initial management, descriptive analysis, and the creation of preliminary graphs and tables. To identify statistically significant differences, the data were subjected to Analysis of Variance (ANOVA) followed by Duncan’s test for post-hoc comparisons, using Statigraphics Centurion 5.0 software. This analysis facilitated comparisons across the two study locations (Lagdo and Yagoua) and among the various agricultural practices and perceptions.

The results are presented through a combination of summary tables and figures. Frequency tables were constructed to display the modalities of key categorical variables, including rice production techniques, field maintenance practices, causes of soil degradation, and the perceived environmental effects. Conversely, graphical representations were employed to illustrate trends in rice-growing areas, the socio-economic importance of rice cultivation, and farmers’ awareness of its environmental impacts.

Rice cultivation is carried out on suitable soil and through practices such as preparing plots, tilling the soil, choosing varieties and maintaining rice paddies.

3.1.1. Soil Appropriate for Rice Cultivation

An analysis of rice production methods in the study area identified several key variables, detailed in Table 2. Farmer responses indicated a strong preference for clay-sandy soil, which was reported as the most suitable type for cultivation by 79.28% ± 2.50 of respondents.

Table 2. Rice production process.

3.1.2. Land Preparation and Tillage

The initial preparation of plots is dominated by the practice of clearing and burning rice residues and weeds (48.74% ± 9.33). This is followed by clearing alone (23.55% ± 0.60), clearing and depositing residues on dykes (19.22% ± 8.74), and burning alone (8.27% ± 0.22). Subsequent tillage is primarily achieved through mechanical ploughing (54.99% ± 29.14), while hand hoeing (33.56% ± 25.34) and animal-drawn ploughing (11.45% ± 3.80) are also employed (Table 2).

3.1.3. Crop varieties and Establishment

Rice farmers cultivate several varieties, with IR46 (53.47% ± 0.08) and Nerica (36.99% ± 0.73) being the most widespread. The Tox variety accounts for a smaller portion of cultivated area (9.55% ± 0.65). For crop establishment, indirect sowing is the overwhelmingly dominant method (94.84% ± 2.04), while direct sowing is practiced minimally (5.16% ± 2.04) (Table 2).

3.1.4. Cleaning of Rice Fields and the Contribution of Bunds

Rice field management is characterized by manual practices, including the clearing of weeds and the construction of water-retaining embankments, often reinforced with the cleared biomass itself (Figure 2Figure 2). While this approach reduces the need for chemical herbicides—promoting aquatic biodiversity and reducing pollution—it also entails considerable occupational hazards. Farmers are directly exposed to humid, hot conditions and are at heightened risk of contracting waterborne diseases and other pathogen-related illnesses.

Figure 2. Cleaning rice fields.

3.1.5. Rice Field Maintenance

Rice field maintenance relies heavily on manual labor and chemical inputs, according to the data. The vast majority of farmers (96.82%) harvest their crops by hand. For fertilization, chemical fertilizers are dominant (83.59%), with organic options used by a minority (16.41%). Pest and disease control is primarily achieved through chemical means (76.10%), while manual weeding is the most common method for weed control (60.04%). Although chemical weeding is practiced, it is most often used in combination with manual methods (27.65%) rather than alone (Table 3).

Table 3. Field maintenance practices (%).

3.2.1. Causes of Soil Degradation and Water Pollution

Data analysis from Lagdo and Yagoua reveals a high level of community awareness regarding environmental issues in rice cultivation, with several significant causes of soil degradation and water pollution identified. Statistical analysis indicates a non-significant difference between the two localities (p = 0.64) but a very significant difference among the perceived causes (p = 0.0089), reflecting variation in their prevalence and impact (Table 4).

Table 4. Causes of soil degradation and water pollution (%).

The primary cause, identified by 96.40% of respondents, was the excessive and often uncontrolled use of pesticides, leading to the contamination of soils, groundwater, and surface waters, thereby threatening aquatic ecosystems and human health. This was closely followed by poor water management (91.23%) and deforestation (91.09%). Poor water management, through inefficient irrigation and the return of agrichemical-laden water, promotes salinization and biological degradation. Deforestation, driven by agricultural expansion, exacerbates soil erosion and diminishes water retention capacity.

Other major factors include flooding (88.05%), attributed to unsuitable cultivation practices which leach nutrients and disperse pollutants; overexploitation of rice fields (87.84%), resulting from a lack of fallow or crop rotation that depletes soil fertility; and the use of chemical fertilizers (85.50%), a key driver of water eutrophication and soil biological disruption. While cited less frequently (81.04%), soil erosion remains a serious consequential problem.

3.2.2. Level of Degradation of Rice Fields

The assessment of rice field degradation over time reveals a cyclical and self-reinforcing problem (Table 5). Data indicate a perceived decline in soil fertility (71.15%), which directly correlates with lower rice productivity (72.57%). This degradation is attributed to practices such as monoculture and the excessive use of chemical inputs. Paradoxically, in an effort to counteract diminishing yields, a majority of farmers (86.36%) report further increasing their application of chemical fertilizers and pesticides. This strategy appears to be counterproductive, as yields continue to decline despite the intensified chemical use, suggesting a state of advanced soil degradation where additional inputs are no longer effective.

Table 5. Level of degradation of rice fields (%).

3.2.3. Consequences of the Decline in Rice Productivity

The decline in rice productivity in Cameroon’s Sudano-Sahelian zone triggers a cascade of severe socio-economic and environmental consequences (Table 6). Survey results reveal a hierarchy of significant impacts (P = 0.01), led by near-universal food insecurity (98.16%) and rising local market prices (97.81%). This economic shock manifests in substantial income loss for farmers and traders (93.35%), which in turn drives profound social disruptions, including increased rural exodus (92.86%) and the under-enrolment of children in school (91.44%). At a macro level, the productivity shortfall has led to increased reliance on rice imports (84.16%) and exerted pressure on other ecosystems (84.09%). No significant difference was observed between localities (p = 0.49), indicating these challenges are consistent across the study region.

Table 6. Consequences of the decline in rice productivity (%)

3.3.1. Importance of Rice Farming

Rice cultivation in the region serves a predominantly dual-purpose function, with the vast majority of farmers (74.19%) producing for both self-consumption and market sale (Figure 3Figure 3). A smaller segment focuses exclusively on subsistence (23.76%), while a minimal proportion (2.05%) are purely market-oriented. This pattern is statistically significant (p = 1.44E−05), confirming that the mixed subsistence-commercial model is the dominant mode of production. Beyond grain production, the crop is integral to the local livelihood system; rice straw is used as a construction material, and rice husks are repurposed as livestock feed, particularly for pigs and ducks.

Figure 3. Importance of rice cultivation.

3.3.2. Changes in Rice-Growing Areas

Survey data demonstrate a predominant increase in the area used for rice cultivation, reported by 89.74% (±2.21) of farmers. A small minority reported stable (6.72% ± 2.06) or decreasing (3.54% ± 0.15) areas (Figure 4Figure 4). The difference between these trends is statistically very significant (p = 8.3386E−05). Respondents identified the expansion strategies of rice companies, motivated by goals of enhancing food security and reducing imports, as a key driver. A major documented consequence of this expansion is deforestation, which raises concerns about associated biodiversity loss and soil degradation in rice-growing areas.

Figure 4. Increase in rice-growing areas over the last decade.

3.4.1. Rice Farmers’ Knowledge of the Effects of Rice Cultivation

Survey results reveal a high level of local awareness (93.28%) regarding the negative environmental consequences of expanding rice farming (Figure 5Figure 5). This perception is substantiated by local ecological knowledge; farmers consistently report the disappearance of numerous animal and plant species following the establishment of large-scale agricultural developments, namely SEMRY and the Lagdo Hydro-Agricultural Project. The primary cause identified for this biodiversity decline is the widespread clearance of natural vegetation.

Figure 5. Rice farmers’ knowledge of the effects of rice cultivation.

3.4.2. Analysis of the Adverse Effects of Rice Cultivation

The perceived environmental and socio-economic impacts of rice cultivation, as reported by farmers, are presented in Table 7. The data reveal a strong consensus on several severe negative effects. Over 90% of respondents identified soil degradation (95.26% ± 0.77), deforestation (94.41% ± 0.77), loss of biodiversity (94.13% ± 0.36), and the conversion of traditional sorghum, millet, and grazing lands (92.86% ± 0.91) as the most significant consequences. This indicates intense pressure on natural resources and a fundamental transformation of traditional agro-ecosystems.

Furthermore, a high prevalence of respondents linked rice farming to public health and climate concerns, including an increased incidence of diseases like malaria and bilharzia (91.16% ± 0.79), perceived climate variation (91.09% ± 0.41), and the proliferation of mosquitoes and mollusks (90.03% ± 1.47). A suite of other significant, though moderately perceived, impacts were also reported, including flooding (84.73% ± 0.83), water and air pollution (82.39% ± 0.61), and the eutrophication of aquatic ecosystems (80.55% ± 0.38). Indicators such as the loss of agricultural land (77.23% ± 0.11) and the proliferation of weeds (77.08% ± 1.73) further illustrate the degradation of agricultural systems.

Statistical analysis confirms that these perceptions are consistent across the two study localities (p = 0.90), indicating a region-wide concern. However, the highly significant difference between the perceived intensities of the various effects (p = 2.4E−7) underscores that rice cultivation generates a suite of multiple, distinct harmful effects, rather than a single uniform impact. The effect with the greatest regional variability was excessive water use (64.56% ± 5.35), suggesting location-specific water management challenges.

Table 7. Adverse effects of rice cultivation (%).

3.4.3. Anthropogenic Flooding and Its Socio-Environmental Consequences

Field observations document significant flooding in the residential Waidoua neighbourhood of Gabaraye-widi village, impacting the public school, a community borehole, and multiple residences (Figure 6Figure 6). This partial submersion, characterized by prolonged water stagnation, is indicative of mismanaged water from adjacent rice cultivation. The functionality of the school is critically compromised; local reports indicate that the academic year now consistently starts late—postponed until late October or early November—due to the inundation of the school grounds.

The flooding is attributed to excess water escaping from nearby rice fields, a consequence of poorly maintained or obstructed irrigation canals. This has led to the inundation of areas not designated for flooding, resulting in material damage to infrastructure and creating a significant public health hazard. The stagnant water serves as a breeding ground for disease vectors, increasing the risk of waterborne illnesses and mosquito-borne diseases like malaria.

Beyond the immediate socio-economic impacts, this situation exacerbates environmental degradation, contributing to soil erosion, contamination of water resources, and a loss of local biodiversity. This case underscores the critical spillover effects of inadequate water management in agricultural zones, directly impacting community health, education, and local ecosystems.

Figure 6.Flooding of a residential area in the Waidoua neighbourhood (Vele).

3.4.4. Direct Socio-Environmental Impacts on a Residential Community

As illustrated in Figure 7Figure 7, the consequences of poor water management extend directly into the daily lives of residents in Gabaraye-Widi. The visual evidence captures the heightened vulnerability of the community, showing women and children collecting water from a borehole amidst flooded surroundings. This flooding, originating from overflowing rice paddies, has inundated homes and compromised sanitation facilities, including those at the Waidoua public school.

This constant exposure to stagnant water creates a significant public health crisis, placing families at a high risk of contracting waterborne diseases such as diarrhoea, cholera, and typhoid, as well as vector-borne illnesses including malaria and bilharzia. Consequently, the population is forced to navigate and reside in persistently unsanitary and hazardous conditions.

This case exemplifies the tangible conflict arising from the coexistence of intensive agriculture and residential areas. The competition for land and water, coupled with the externalities of flooding and unsanitary conditions, creates socio-economic tension and leads to the seasonal loss of habitable land, underscoring the urgent need for integrated land-use planning and improved water governance.

Figure 7. Exposure of residents to health risks.

3.4.5. Infrastructure Neglect and Its Consequences

Figure 8Figure 8 illustrates the primary irrigation and drainage canals, which are critical infrastructure for regulating water flow within the rice cultivation scheme. Their intended functions are to deliver water to the paddies and efficiently remove excess water to prevent waterlogging, plant rot, and flooding. However, field observations reveal that these canals are heavily colonized by aquatic vegetation, including species such as Nymphaea lotus, Nymphaea micrantha, Pistia stratiote, Ipomoea carnea, and Oryza latifolia. This proliferation, combined with an apparent lack of regular dredging, significantly impedes the hydraulic capacity of the channels. The consequent restriction of normal water flow leads to canal overflows, which are a direct cause of the flooding observed in adjacent areas. This malfunction not only damages crop through submergence and nutrient leaching but also triggers secondary environmental impacts, including erosion and the further spread of invasive species.

(a) (b)

Figure 8. Main channels: drainage channel (a) and irrigation channel (b) of SEMRY.