370 



SOIL PHYSICS AND MANAGEMENT 



obliterated in other ways. Otherwise, each rain will increase their 

 size and they will become a permanent source of trouble. In a 

 few years considerable areas will be ruined. Gullying in different 

 degrees is seen in figures 182, 183, and 184. 



Methods of Prevention and Filling. 1. Straw-brush. 



Fia. 182. 



Fio. 183. 



Fia. 182. Erosion in pasture near crest of slope. 

 Fio. 183. Old field erosion in Mississippi. 



Gullies should be filled with a durable material sufficiently open 

 to allow the water to pass through it and yet reduce the velocity of 

 the current so as to cause deposition. The material best suited 

 depends on conditions. If the slope ^is gentle and the quantity of 

 water small, straw, weeds, or anything of that nature holds the soil, 

 that would otherwise be lost, partially filling the gully. Where the 

 t 



