Read the passage below carefully:
Across the semi-arid Sahelian belt of West Africa, climate variability and intensive land usage have accelerated soil degradation, threatening agricultural yields and local food security. Historically, topsoil erosion stripped vast farmlands of essential organic matter, rendering traditional cereal cultivation increasingly unsustainable. In response to this ecological crisis, indigenous farmers resurrected and adapted 'zaï' pit techniques—a traditional soil-restoration practice involving the manual excavation of small, shallow basins across crusted fields. During the dry season, farmers dig these pits and fill them with organic matter such as manure and crop residues. This practice attracts termites, whose subterranean channels loosen hardpacked soil and enhance water infiltration when seasonal rains arrive. Consequently, zaï pits effectively capture sparse rainfall and concentrate vital nutrients directly around seeds, turning barren crusts into productive plots for sorghum and millet. Beyond immediate yield improvements, the widespread adoption of zaï farming has fostered community-led reforestation, as tree seeds embedded in compost germinate alongside crops. By combining ancestral ecological wisdom with localized labor, West African agricultural communities have established a resilient framework for reversing desertification and securing rural livelihoods without relying on capital-intensive technology.
Based on the passage, in what sequence does the author present the central key points of the summary?
- 1Severe land degradation and topsoil erosion jeopardized traditional cereal farming in the Sahel.
- 2Farmers resurrected traditional zaï pit techniques to manually capture water and organic matter.
- 3Organic enrichment in the basins enhanced termite activity, soil permeability, and crop productivity.
- 4The practice evolved into a broader framework for community reforestation and resilient rural livelihoods.