MAINTAINING THE ORGANIC MATTER OF SOILS 161 



clovers are biennials and can be seeded one year with a nurse crop 

 and allowed to produce a growth the ne.xt spring before turning 

 under. Hairy or winter vetch may be seeded with rye or winter 

 oats for early spring pasture and plowed under for corn, cotton or 

 other crops. It is a common practice in the corn belt to sow clover 

 with wheat, oats or rye and turn it under in the fall or the fol- 

 lowing spring for corn. Sweet clover is excellent for this purpose 

 in many localities. One to two tons of dry material have been 

 turned under in time for the corn crop without apparent injury. 

 There is danger, however, from plowing under a large amount of 

 green material to be followed by a crop of corn, cotton, or potatoes. 

 During the last few years some complete failures have resulted from 

 this practice. The green crop takes out much of the available 

 plant food and moisture and may leave the soil so deficient in these 

 that the crop which follows may be seriously injured. Besides, the 

 fermentation of the green material may develop heat that will drive 

 off some moisture and leave the soil still drier, although the large 

 amount of water turned under with the green crop would tend to 

 compensate for any lost in this way. 



5. Catch and Cover Crops. Many times it is advantageous 

 to use crops for some 'special purpose in which no attempt is made 

 to grow them to maturity. Legumes, rye, oats or other crops are 

 sometimes sown on laiid that is to lie idle for a time in order to use 

 the available nitrates and prevent their loss by leaching. This 

 plan rs especially advisable on sandy soils, but it may be applied 

 to other soils to good advantage. Wheat on sandy land could be 

 immediately followed by cowpeas, which not only conserve the 

 nitrates but add nitrogen to the soil. Wheat and oats on heavier 

 soils, such as silt and clay loams, are usually followed soon after 

 harvest by a crop of weeds and grass which act as very efficient 

 catch crops. Wherever possible legumes should be grown after 

 oats, wheat, or barlev for this purpose because of their double value. 

 Cow-peas, soybeans or clover are sometimes seeded in corn at the 

 last cultivation to be used as a soil-improving catch crop. They 

 may also be seeded in the hill of corn without serious detriment 

 to the corn. Kape. cowhorn turnips, or rye may be used as catch 

 crops. These may be pastured and thus acquire an additional 

 value. 



The same crops may he n-spd as cover crops in orchards to 

 hasten the maturity of wood or on hillsides to prevent washing. 



6. Barnyard Manures. Manure is one of the most valuable 

 11 



