Figure 9.12

Agriculture on slopes. (A) Contour plowing in Montgomery County, Iowa. This farming method creates furrows that follow a line of equal elevation on a slope. It prevents water from collecting in small channels that run downslope and erode the soil. The green strips of vegetation catch sediments and further reduce soil loss. (B) Banaue Rice Terraces, Philippines. Terracing is a farming method used on very steep slopes. For over 2,000 years, rice has been sustainably grown in the Philippines using this method. (C) Most of Haiti’s hills are severely eroded due to farming on steep slopes without protective contouring or terracing. The hills shown here were once forested. The native vegetation was cleared for farming or cut for fuel. Erosion then washed away the soil, leaving the hills permanently damaged and largely without cover.

(A. Photo by Tim McCabe, USDA Natural Resources Conservation Service; B. © Travel Ink/Gallo Images/Getty Images; C. © James P. Blair/National Geographic/Getty Images)