CHAPTER III. 



MAINTAINING SOU FERTILITY. 



As the fertilizer ingredients nitrogen, phosphoric acid and 

 potash are the plant food elements that have to be supplied, let 

 us find out some of the ways they are taken away from the soil 

 and methods of preventing and restoring their loss. 



Erosion is the loss of soil by the action of water or wind. 



Any one who has ever lived in the South is familiar with the 

 tremendous losses of fertility incurred by erosion. The most 

 serious losses occur on hilly clay soils. Cotton and corn are 

 grown on many of the southern soils year after year and the 

 soil is left bare during the winter. These soils are not plowed 

 very deep and when a heavy rain comes only a small amount of 

 the water can soak into the soil. If the land is hilly the rain 

 forms little rills at first which finally become gullies and much 

 of the good fertile soil is washed to the valleys or bottom lands. 

 It a few seasons a great deal of such hill land becomes unpro- 

 ductive. 



There are other sections in America besides the South where 

 erosion is damaging farms. In some of the far western states 

 and other sections where the land is hilly, erosion is a source of 

 loss of fertility. 



Erosion by water besides carrying away the most fertile part 

 of the soil puts the land in such a condition that it is difficult 

 to operate. Gullies are objectionable in growing crops. 



On light sandy soils the blowing away of the surface soil by 

 wind often results in serious losses of fertility. Mounds or 

 ridges are often formed which interfere with cultivating the soil. 



Ways to Check Erosion. — Plowing up and down hill is very 

 bad practice as the furrows become regular waterways during a 

 rain storm. In the South the lands that are subject to erosion 

 are usually the clay soils which will not absorb water readily. 

 Shallow plowing is practiced and deep plowing will cause more 

 water to be absorbed and retained. Most of these soils are lack- 

 ing in organic matter. By growing green crops in the winter 



