Composed of a variety of islands separated by inlets, the Saloum Delta Biosphere Reserve is located in west-central Senegal between the city of Joal-Fadiouth to the north, the Republic of Gambia to the south and the Atlantic Ocean to the west. Formed by the confluence of the Sine and Saloum rivers, it is a rich natural ecosystem with an area of 232,500 hectares, including 58,300 hectares of mangroves [8] and [9] . It includes (11) classified forests, four (04) marine protected areas (Joal-Fadiouth, Sangomar, Gandoul and Bamboung) and one (01) community nature reserve (Palmarin). Figure 1 shows a presentation of the Saloum Delta Biosphere Reserve.

The Saloum Delta is a ria that operates in an “inverse estuary”, meaning that it increases rather than decreases by going up from the sea upstream. This hydrodynamic phenomenon is due to the large predominance of evaporation on very small and limited freshwater supplies during the rainy season, which leads to a reverse flow, with seawater replacing the volumes lost by evaporation, allowing salt water to enter deeper and deeper into the land, due in part to slow flow of both rivers [10] .

Mangrove riparian communities are highly dependent on these ecosystems, both for their environment (protection from swells and the effects of climate change) and for their livelihoods (fishing, seafood harvesting, beekeeping, etc.) The Saloum Delta has been suffering for several years from the adverse effects of climate change and unsustainable practices. This has resulted in intense coastal erosion at some parts of the Delta’s coastline and an increase in water salinization, which reaches 120 at the end of the dry season in the extreme upstream part of the Saloum 2. Furthermore, poor practices such as the unruly occupation of the coastline, deforestation, excessive cutting of mangrove forests for smoking and baking activities, overfishing and poor waste management, especially plastic, they are responsible for the degradation of ecosystems.

As part of enhancing the livelihoods of local communities in the Saloum Delta, which are severely affected by the concerning phenomenon of land salinization, a campaign to recover abandoned rice valleys has been initiated across nine (9) villages in four communes. These include the large valley of Kabongoye-Mbissel in the commune of Fimela (23 ha), Ndiaye-Ndiaye (10 ha), Bangalaire (1 ha), Keur Fafa (3.5 ha), Ndorong Wolof (2.5 ha), and Bambougar (2.5 ha) in the commune of Diossong; Félir (3.5 ha) in the commune of Djirnda; Boli-Ndour-ndour (5 ha) in the commune of Djilor; and Bétenti (1 ha) in the commune of Toubacouta. The spatial distribution of these sites is detailed in the following Figure 2 .

The strategy used for the recovery of salty land is mainly based on the use of phosphogypsum, organic matter (manure and/or groundnut shells, poultry dung) and the rice variety Sahel 108. From a practice point of vies, the activity is structured around the following main tasks:

Plowing: Tillage is a method of turning the soil to bury plant debris and fertilizer, expose the deep part of the soil to the sun and facilitate gas exchanges between the soil and the atmosphere. It is often done with a tractor or trolley. As part of this scheme, we have carried out a tri-cross ploughing; first a cross plough before spreading the inputs at a depth of 15 cm then a third light ploughing to bury them. However, if there is not a large quantity of herbs, we were able to do a cross plough; Before and after application of inputs.

Phosphogypsum: Phosphogypsum is a by-product of synthesizing fluorapatite and sulfuric acid. Its composition varies significantly depending on the natural phosphates from which it is derived. It mainly serves as a source of calcium (CaO) and sulfur (S). It is particularly effective in reducing soil salinity due to its desalination properties. The application of phosphogypsum ( Figure 3 ) provides the soil with sufficient calcium sulfate to flocculate clay, improving its workability. Its addition to saline lands allows the calcium it contains to gradually replace sodium in the exchange complex, thereby reducing soil salinity in the presence of water. As a source of calcium and sulfur, phosphogypsum can logically be considered a product with some fertilizing value, improving soil structure and facilitating water infiltration.

Organic Matter: When used appropriately, manures help maintain fertility and enrich the soil by providing nitrogen, carbon, phosphorus, magnesium, and calcium, increasing the availability of nutrients, improving soil structure (aggregate formation), biological activity, and water retention capacity. Cow manure is a mixture of cow dung and bedding straw. As large herbivores, cattle contribute significant amounts of humus to the soil, which is essential for healthy plant growth. It strengthens light soils, improves soil fertility, enhances crop quality, and boosts yields. However, it is not advisable to use fresh cow manure, as it can harm human health and plant growth; the decomposition of fresh cow manure generates high-temperature fermentation (over 55˚C) that can burn roots and plants. For this reason, it is recommended to wait at least one year before applying cow manure as shown in Figure 4 . This type of organic matter is used in this experimental phase because of its availability in the area, to facilitate the appropriation of the technique by the communities.

Plant Material: The Sahel 108 variety selected is suitable for winter cultivation (early and late sowing, 110 days and 125 days, respectively); it has good grain quality (thin and long, mutique), a potential yield of 10 tons per hectare, and is favored for its taste and culinary qualities by homemakers. This variety was chosen for the trial because it is the most commonly used in the delta and is notably sensitive yet tolerant to salinity. Figure 5 below shows the rice application system.

The monitoring and evaluation of the experimental land recovery system focused on several soil and agronomic parameters.

Soil Parameters: Composite soil samples (from the surface and 20 cm depth) were collected at the study sites for analysis. A total of 89 sampling points were taken in the managed area and 10 in the unmanaged area to serve as controls. The selection of points was done randomly and stratified, ensuring they were at least 20 meters from the edge to minimize border effects. The collected soil samples ( Figure 6 ) allowed for the determination of nutrient content, soil structure, soil texture, and soil salinity and acidity, among other factors.

Agronomic Parameters: Regarding agronomic parameters, 10 yield plots of 1 m² each were established in the managed area. Within these plots, organic matter samples were collected ( Figure 7 ) to define a set of agronomic parameters, including production yield, number of grains per panicle, mass of 1000 grains, average height of ears, and average tillering of the rice. These biological parameters, compared to those of the variety grown under normal conditions, allowed for the assessment of the system’s effectiveness. To minimize border effects, the yield plots were also placed at a minimum distance of 20 meters from the edge.

Semi-Structured Interviews: In addition to the collected samples, producers’ opinions on the system were gathered through a mixed focus group of producers and five individual interviews. These exercises allowed beneficiaries to express their views on the system’s effectiveness. They also provided insights into current needs, which will serve as a foundation for developing a future valley management plan.

The application of phosphogypsum and manure must be tailored to the soil characteristics and cultivation objectives. Phosphogypsum can be spread uniformly over the soil surface or incorporated using cross or triple plowing. Manure can be applied on the surface or buried to facilitate its incorporation into the soil. Ideally, a cross plow should be done first to bury straw and weeds, whose decomposition also enhances soil fertility. Following this, inputs such as phosphogypsum, rice seeds, manure, and/or peanut shells should be applied before performing a final light plowing. Besides cow dung and peanut shells, other types of organic materials such as poultry litter and goat or sheep droppings can be used with similar effects. The application rate should be adjusted based on the specific soil characteristics and crops. In the Saloum Delta, site characterization for rice production has established a standard dosage that can be followed in the absence of physical-chemical soil analysis. This is set at 0.5 tons/ha for phosphogypsum and 2 tons/ha for organic matter, with the type and proportions depending on availability.

The support provided to producers is unanimously appreciated. In fact, 100% of producers surveyed in the perception study affirm that the system based on the application of phosphogypsum and organic matter, such as manure and/or peanut shells, is very profitable. It has given a second life to lands abandoned due to salinity, resulting in very satisfactory outcomes. These are primarily marked by a significant reduction in salinity, leading to highly favorable yields. The evolution of salinity before and after the intervention, evaluated through electrical conductivity, is represented in the following Figure 8 .

The analysis of the above figures indicates a significant decrease in electrical conductivity after the implementation of the land recovery system. The electrical conductivity of soils determines their level of salinity. Before the system was established, this variable had very high values typically ranging from 1000 to 7000 μS/cm. In fact, most of the rice-growing lands in the Saloum Delta fall between class III and class V, which does not support crop development in the area. Productivity of most rice crops begins to be negatively affected at levels starting from 1000 μS/cm. The following Table 1 provides information on the classification of soils and the behavior of rice crops based on variations in electrical conductivity.

As observed in Figure 3 and Figure 4 , the land recovery system implemented has successfully brought soils previously classified between Class III and Class V back to Class I, indicating non-saline soils. In addition to electrical conductivity, other soil parameters such as pH and soil fertility have shown very positive changes. Indeed, the soils were slightly acidic, with pH levels around 6 or lower across all sites, and the C/N ratio was very low due to minimal or absent mineralization of organic matter before the system was implemented. By the end of the agricultural season, acidity had significantly decreased, resulting in nearly neutral pH levels. There was also a substantial increase in soil fertility, reflected by a significant rise in the C/N ratio. These results are partly confirmed by those from the agronomic monitoring summarized in the following Table 2 .

This refers to the formation of tillers located at the same level of the stem, at the base of the plant, creating a tuft characteristic of grasses. The number of tillers per plant is closely related to the spacing observed during sowing. In the managed valleys, the average tillering is estimated at 3 tillers per plant, demonstrating adherence to proper spacing during sowing, which allows for good vegetative development of the crops.

Average height is an excellent indicator of the vegetative development of rice. The height of the tillers at the managed sites ranges from 72.32 to 114.48 cm, with an average of 93.4 cm, slightly above the average listed for the Sahel 108 variety used, estimated at 90 cm. This robust growth is linked to the ample water supply in certain valleys during a favorable period.

The number of grains per panicle is significant, varying between 101 and 201 grains/panicle, with an average of 151 grains/panicle. This relatively high value has contributed to satisfactory productivity. Figure 9 below shows some of the rice panicles produced.

This variable provides insights into the quality of the production and is heavily influenced by the quality of the grains obtained. In the managed valleys, 1000 grains of produced rice weigh on average 23 g, indicating very good quality, even though this value is slightly below the potential of the Sahel 108 variety, estimated at 24 g.

The yield plots established in the managed areas allowed for an estimation of the average yield at 6.17 t/ha. This value may seem low compared to the potential of Sahel 108, estimated at 10 t/ha. However, the yields for this variety vary between 6 and 7 t/ha in the Senegal River valley. It should be noted that producers reported a significant presence of weeds, which slightly impacted production, highlighting the need to improve the tillage system to reduce weed growth.

All these factors collectively indicate that the yields obtained are very satisfactory. Moreover, all producers surveyed during the last monitoring mission confirmed that with the addition of phosphogypsum and dried cow manure and/or peanut shells, the yields are very good. This has led to a strong demand for participation in the upcoming campaign, even from neighboring villages.

The extrapolation of the average yield obtained over the entire 58 ha managed area allowed for an estimation of total production at 357.58 tons of rice. This has significantly contributed to improving the livelihoods of local communities, while reducing the risk of food in security in the area. Figure 10 shows rice production.

To analyze the economic profitability of the salt land recovery system, an estimation of the production cost per hectare has been summarized in the following Table 3 .

The largest investment in the salt land recovery technique occurs in the first year, primarily due to the costs associated with mobilizing inputs such as phosphogypsum and organic matter. During this initial campaign, the investment cost can reach up to 437,000 CFA francs. In subsequent seasons, investments will significantly decrease as there is no longer a need for additional input; the decomposition of rice straw residues alone suffices to maintain soil fertility. Thus, a flat amount of 167,000 CFA francs could facilitate good production.

Considering the average yield of 6.17 t/ha or 6170 kg/ha, with a selling price of 7000 CFA francs per 40 kg sack of paddy, the total revenue is estimated at 1,079,750 CFA francs. This results in a profit of 247% in the first year and 646% in the following years.

Soil salinization is one of the most severe constraints in production systems across Sub-Saharan Africa [11] . In Senegal, many regions face the challenge of land salinization, particularly in the natural region of Sine Saloum, where the Saloum Delta biosphere reserve is located. Research conducted by the National Institute of Pedology (INP) in 2008 estimates that nearly 1,000,000 hectares of land are affected by salinity [12] and [13] . This phenomenon has led to the abandonment of vast areas of saline rice fields in favor of activities that are not necessarily beneficial to the environment because according to [14] , the salinization negatively impacts the physical, chemical, and biological properties of the soil.

Fortunately, there is hope through the salt land recovery technique based on the use of phosphogypsum and organic matter, such as manure and/or peanut shells. This method has yielded very positive results, improving both the physico-chemical and agronomic parameters.

[15] reported that the improvement of physico-chemical parameters, phosphogypsum reduces the electrical conductivity (EC) or salinity of the soil, thus enhancing plant nutrition and leading to good yields. A similar finding was made [16] and [17] , who points out that phosphogypsum combined with other organic amendments is effective in reducing the salinity of saline and sodic soils. These results also confirm those of [18] and [19] , who found that gypsum significantly improves paddy yields. For [20] the combined phosphogypsum and cow dung treatment had the highest yield compared to the other treatments. Their study showed that, the treatment with phosphogypsum alone, obtained an average yield compared to the phosphogypsum + cow dung combination. Some researchers, such as [21] and [22] recommend the use of organic and mineral fertilisers, which would give a good yield compared with the control; this is not the case here, given the potential risk of these elements to the environment.