7 wonders of the soil
In arid regions drought, overgrazing, intensive farming, mining and de-forestation can turn once-fertile land into desert. One way to restore the soil is to plant trees, particularly those that ‘fix’ nitrogen by drawing it from the atmosphere and making it available to other plants. These trees are typically deep-rooted, helping to retain moisture in the soil, and also improve soil structure by providing leaf litter. Acacias are popular because they grow quickly and can thrive in harsh conditions. In Hawaii, Acacia koa establishes vegetation on overgrazed lands; in India, Acacia nilotica rehabilitates degraded saline soils; in Australia, Acacia saligna is re-greening sand-mining sites. The FAO’s 2004 Acacia Project has already benefited 44 communities in six African nations by planting acacias in vulnerable farmland. The trees help restore soil fertility, provide fuelwood and fodder, shelter crops and are a source of gum Arabic, which is collected and sold to the food industry.