Thirty-fourth Annual Convention. 289 



for green manure or pasture in the spring. Cowpeas may be used 

 with fair success, especially in the southern part of the state, but 

 they do not have the binding power of rye and are killed by 

 frost. Clover, either red or alsike, may make sufficient growth 

 during favorable seasons to protect the soil during winter and 

 spring, but they are not so sure as rye unless the soil is treated or 

 especially adapted to them. Much of this rolling land in southern 

 Illinois is sour and must be sweetened with lime or ground lime- 

 stone before clover will do its best. These legumes are very 

 beneficial to the soil for another reason that has been mentioned 

 before. The clover may be left as a green manure and turned 

 under in time to plant another crop, as corn, or it may be har- 

 vested or pastured. It must always be borne in mind that a large 

 growth of clover removes a very large amount of moisture from 

 the soil, and when turned under as green manure in dry seasons 

 it may leave the soil so dry that the succeeding crop will suffer. 



In general, any crop may be grown that will furnish sufficient 

 material both of top and roots to hold the soil in place. Rye and 

 timothy seeded in the fall with red clover and alsike seeded in 

 the spring, followed by pasturing is one of the very best methods. 



2. Increasing the Organic Matter Content.- — The amount 

 of organic matter varies quite widely with the type of soil. The 

 upland timber soils of the state have in general much less 'organic 

 matter than the prairie types. The chief reason for this is the 

 fact that the roots of prairie grasses were protected from ulti- 

 mate decay by the moist soil while the leaves of the trees falling 

 upon the surface of the ground were exposed to the air and al- 

 most complete decomposition took place. Some samples of orig- 

 inal prairie soil have been collected and the amount of roots 

 determined to a depth of six inches. One and one-half per cent 

 of the weight of the soil was roots, both in black clay loam cov- 

 ered with tall slough grass and in brown silt loam growing the 

 common blue stem of the prairies. This means that there were 

 about twelve tons of roots per acre in the surface six inches of 

 soil. Such a growth of fibrous roots is never found in the upland 

 timber soils. The following table gives the per cent of organic 

 matter in the surface and sub-surface strata of the principal types 

 of timber and prairie soils of the state, calculated from the total 

 amount of organic carbon found in those soils by the Division of 

 Chemistry of the Experiment Station.* 



