ORGANIC MATTER AND NITROGEN 



323 











Organic matter has a wonderful effect in loosening heavy soils. 

 Improvement in this direction can best be accomplished by growing 

 grass and by pasr 

 turing. Combin- 

 ing red-top, timo- 

 thy and clover 

 makes an excellent 

 grass mixture for 

 any heavy soil. 

 The roots of 

 grasses loosen the 

 soil and in a large 

 measure prevent 

 puddling. 



The growing 

 of sweet clover on 

 clays for soil im- 

 provement is 

 highly recom- 

 mended. The 

 deep roots pene- 

 trating the ' ' tight' ' 

 subsoil improve 

 drainage, favor 

 aeration and add 

 much organic 

 matter (Fig. 214). 



The use of air- 

 slaked lime or 

 quicklime on clays 

 tends to develop 

 better tilth, espe- 

 cially when acid. 

 This effect, how- 

 ever, is percepti- 

 ble only when 

 lime is used con- 

 tinuously for 

 several years. Usually clays are not acid or only slightly so. 



Organic Matter and Nitrogen. — Clay soils are commonly 

 deficient in organic matter and nitrogen, especially those which 



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Fig. 214. — The upper portion of a sweet clover root, 

 roots will puncture tight and hard subsoils. 



Such 



