322 MANAGEMENT OF CLAYS AND DEPLETED SILT LOAMS 



Importance of Drainage. Drainage is usually the first step 

 in the improvement of clays, since they are so retentive of moisture 

 and do not permit water to percolate easily through them. Thus 

 it is that clay soils are usually wet and cold and lack proper aera- 

 tion. Attention should be given both surface drainage and tiling 

 (Chapter IX) . Through proper surface and under-drainage these 

 soils warm up better, become better aerated, and are much 

 improved in their productiveness. 



Fid. 213. When heavy soils are plowed too wet they become puddled.' Hard lumps result. 



Tilth. The greatest problem in the cultivation of clays con- 

 cerns tilth (see index). When plowed or worked too wet the soil 

 particles are forced together, and the result is a hard, lumpy soil 

 when it becomes dry (Fig. 213). When exposed to a hot, drying 

 sun a moist or wet clay easily bakes. The preparation of a good 

 seed bed, therefore, is difficult and requires much extra labor 

 (see "Clod Crushers")- 



Thorough drainage is an important factor in the development 

 of good tilth. A second consideration is careful plowing. Clays 

 should never be plowed or worked when they are wet. Often the 

 bad effects of plowing heavy soils when too wet extends through 

 several years. When such lands have become hard and lumpy 

 because of careless plowing, freezing and thawing is about the only 

 process that will restore a crummy or granular structure. This is 

 best accomplished through fall plowing. 





