Thirty-fourth Annual Convention. ^^^ 



Early Wisconsin Glaciation — 



Black clay loam (prairie) 7.24 3.39 



Brown silt loam (prairie) 5.01 3.10 



Light-gray silt loam 



Tellow-gray silt loam . .• 



Yellow silt loam 



timber 2.11 -70 



Late Wisconsin Glaciation — 



Black clay loam (prairie) 10.05 7.00 



Brown silt loam (prairie) 7.17 3.53 



Light-gray silt loam 



Yellow-gray silt loam 



Yellow silt loam 



timber 2.63 1.08 



Average for timber soils 2.00 .76 



Average for prairie soils 5.30 3.23 



From the above table it will be seen that the average amount 

 of organic matter in the surface stratum of timber soils is 2.00 

 per cent, while prairie soils have 5.30 per cent. The effect of or- 

 ganic matter on a soil is to keep it' loose and in condition so it 

 will not compact readily and to bind the finer soil particles into 

 granules or crumbs, both of which tend to make the soil more 

 porous. This increase of porosity gives a greater power of ab- 

 sorption, and in this way diminishes the amount of surface run-off 

 and lessens the washing. Soils rich in organic matter do not 

 wash badly because the granular structure is developed in them, 

 and these compound particles will not be carried so readily by the 

 water as the individual particles. In soils deficient in organic 

 matter, a heavy rain will so compact them that but little absorp- 

 tion can take place. When the surface of such a soil dries it 

 becomes very hard and forms what is commonly called a ''crust." 

 With a fair supply of organic matter in the soil it is not difficult to 

 keep a mulch on the surface for conserving moisture. 



One of the most important things in the management o-f the 

 soils of rolling land is to increase the organic matter content, not 

 only because of the effect it has in preventing washing, but also 

 because of its value in producing good tilth, in increasing the 

 moisture capacity, in conserving mosture, in aiding ventilation 

 and in furnishing a supply of nitrogen for the plant. To increase 

 the organic matter in soils it is necessary to utilize all of the vege- 

 table matter produced. Farm manure should be turned back into 

 the soil as soon as possible. Too often it is left piled up against 

 the barn to rot the boards and leach away. Weeds, stubble, and 

 corn stalks should be plowed under instead of being burned, as is 



