2.  The world’s population is increasing at an alarming rate.  All of these people need to eat.  However, less than 25% of the Earth’s land can be used to grow crops.

3.  Soil fertility – the ability of soil to grow plants.  Certain types of soil are best suited for certain crops.  Many things currently threaten soil fertility.

4.  Soil depletion occurs when the soil gradually becomes so lacking in nutrients that it can no longer be used to grow a usable crop.  Farmers can do some things to prevent this. › Example: Allowing the soil to rest by rotating crops.

5.  Irrigation is often used to make soils fertile.  Irrigation water often brings in dissolved minerals.  These dissolved minerals are often salts.  Over time, the buildup of salt in the soil is called salinization. › Often renders the soil completely useless.

6.  Windbreaks › Also known as shelter belts. › Lines of trees planted along the edges of fields.  Contour farming › Farmers plant crops parallel to land contours to prevent water from running rapidly down a slope.

7.  Terraces › Flattens a slope into separate terraces to slow the speed of runoff.  Strip cropping › Alternate rows of crops to minimize soil erosion.  No-till › Method of farming where everything is done at once (plowing, planting, fertilizing, weed control) and the soil is left completely alone until harvest time.