SOME GENERAL PRINCIPLES 4I 



nish channels down which the surface water perco- 

 lates, if present in excess. Thus it is that clover 

 aids in draining lands under the conditions named. 

 The channels thus opened do not close immediately 

 with the decay of the clover roots, hence the down- 

 ward movement of water in the soil is facilitated for 

 some time subsequently. 



It has been stated that clovers have more power 

 than some other plants to gather plant food in the 

 soil. In some instances they literally fill the soil with 

 their roots. When other plants are sown after the 

 clover has been broken up they feed richly on the 

 decaying roots of the clover. Thus it is that clover 

 gathers food for other plants which they would not 

 be so well able to gather for themselves, and puts it 

 in a form in which it can be easily appropriated by 

 these. The nitrogen in clover is yielded up more 

 gradually and continuously as nitrates than it could 

 be obtained from any form of top dressings that 

 can be given to the land. In this fact is found one 

 important reason why cereal grains thrive so well 

 after clover. 



Since the roots of clovers act so beneficently on 

 soils, it is highly important that they be increased 

 to the greatest extent practicable. Owing to the rela- 

 tion between the growth of the roots of plants and 

 the parts produced above ground, development in 

 root growth is promoted much more when the clo- 

 ver is cut for hay than when it is fed off by graz- 

 ing. Experiments have also demonstrated that the 

 development of root growth is much enhanced in 

 medium red clover by taking a second cutting for 



