The topsoil is the richest in organic matter. Soil erosion causes silting of waterways B. Solutions 1. Less plowing a. Use green manure crops 2. Use of contour strip intercropping , a new method used where wind erosion is a problem, along with crop rotation 4.
Water is necessary for plant growth.
Irrigation is needed to farm areas that do not have sufficient rainfall to water crops. Many areas of the US could not otherwise be used for the crops that consumers will buy. B. Solutions 1. Deserts are increasing alarmingly due to both natural processes and human activities 3. Worst problem in sub-Saharan Africa 5.