**2. Study Area**

Senegal is located in the West African continent, with a land area of 196,722 km2. It is located between the latitudes 12◦20 and 16◦20 N and the longitudes 11◦20 and 17◦30 W [41]. Ecologically and agriculturally, the country is subdivided into six geographical eco-zones [42]. Our research concerned the Groundnut Basin. It covers the administrative regions of Diourbel, Thiès, Kaolack, Fatick, Kaffrine, part of the Tambacounda region (departments of Koumpentoum and part of the department of Tambacounda) and the department of Kébémer [43]. Therefore, our study focuses only on the five administrative regions (Figure 1). They are considered most important in this area because they occupy almost all the arable land in the Groundnut Basin, and constitute an area of very high agricultural production in Senegal [44]. It has a population of 6,436,912 people according to the population censuses in 2013 [45], and covers a total area of 34,964.36 km2, with a density of 184.10 people per km2. The distribution of arable land by agro-ecological zone shows that the Groundnut Basin represents 70% of arable land [46]. Throughout the Groundnut Basin, the cropping systems are mainly cereal-leguminous rotations [47], and it is dominated by subsistence production of millet, maize, groundnuts, cowpeas, and bissap (hibiscus) [48]. Groundnut Basin is characterized by degraded and patchy open forests dominated by *Bombax costatum*, *Lannea acida*, *Pterocmpuserinaceus*, *Sterculia setigera*, *Khaya senegalensis*, *Daniellia oliveri*, *Detarium senegalensis* [49].

With a poverty rate of 47% in 2011 [50], agriculture in Senegal has always been seen as the foundation of the country's socio-economic development [51]. In terms of economic activities, this sector is dominated by agriculture and occupies 74% of the population in the area [52]. Its average in terms of gross domestic product (GDP) ranged from 21.24% (1960–1989) to 15.26% (1990–2011) [53], and further to 16.1% in 2017 [54]. According to data from the National Agency for Statistics and Demography (NASD) site, in 2020, the areas planted (in hectares) in peanuts represent, respectively, 55.16% (2017) and 63.15% (2018) of the national areas (in hectares) planted. In 2013, the population censuses showed that 70% of farms were small family farms with an area of fewer than five hectares [45]. In the study area, the median value of annual rain-fed crop sales per household in 2018 is around \$246.61. According to the NASD site, the percentage of farm household members with agricultural education vary from 5.34% in 2017 to 0.67% in 2018.

**Figure 1.** Geographic information: (**A**) represents the blue color represents the localization of the study area within Senegal; (**B**) represents the Groundnut Basin with five regions.

In fact, in Africa, particularly in the Sahel, after the rainy periods of the 1960s, many researchers noted anomalies of rain in the early 1970s [55]. The consequences of this rainfall deterioration are reflected in Senegal by the degradation of the natural environment, with drought leading to the degradation of the plant cover, the soils being subjected to erosion and runoff, and the accentuation acidification and salinization [56]. In addition, the factors of low annual rainfall, frequent dry spells, and the rainy season shortening affect the vegetative cycle of crops [57]. Severe droughts, especially in northern regions, appear as the biggest risk in estimated aggregate losses to crop and livestock [58]. In Senegal, agriculture is mainly rain-fed and depends heavily on seasonal rainfall amounts, and distribution [59]. Therefore, the combined effect of rainfall, land surface temperature, and solar radiation explain approximately 40% of the variation in cropland productivity over West Africa at the 95% significance level [60]. This situation underlines the fact that the evolution of agricultural land, and climate are closely linked. Drought is a recurring phenomenon in the coastal zone of Senegal and its hazards affect the economies of the predominantly agricultural population [61].

The main factors affecting land-use in Senegal are manifold. Firstly, lots of land areas were changed by the urban setting and associated rapid growth and transformation of human societies in Senegal [42]. In 2015, Senegal's population was estimated at 14,356,575 people with an average annual growth rate of 2.7% [45]. The growth of the rural population has brought greater pressure on land and natural resources and contributed to land fragmentation, particularly in densely populated and high-potential areas with easy access to markets [62]. As a result, in Sangalkam, around Dakar (capital of Senegal), some 7.64 km<sup>2</sup> of agricultural land use was officially developed in the area between 2003 and 2009 [63]. The law n◦ 64–46 of 17 June 1964, governs land management in Senegal, which stipulates, land does not belong to the State, territorial communities, or users, but the "Nation" [63]. Local governments are responsible for the allocation/dedication of land in the national domain for rural activities [64]. Secondly, the chronological summary of agricultural policy in Senegal has gone through several phases. The literature shows the Agricultural Program (1960–1980), the New Agricultural Policy (1985–1994) and the Agricultural Development Policy Programs, letters and Declaration (1995–2003). Since the 2000s, we have seen a reconfiguration of the situation regarding agriculture. For example, we have the Law of

Agro-Sylvo-Pastoral (LOASP) in 2004. Since 2013, Senegal has defined a new agricultural policy called the Program to Accelerate the Cadency of Senegalese Agriculture (PRACAS). Despite all these agricultural policies, Senegalese agriculture still faces difficulties [65]. Third, soils in Africa affected by water erosion ranging from medium to high effect cover an area of more than 12 million hectares, or 18.5% of the total national territory [66]. The Groundnut Basin is today confronted with chemical and physical-biological degradation which has become more intense. Thus, the soils are impoverished, restructured, chemically exhausted by wind and water erosion, recurrent droughts [67].
