ROTATION OF CROPS. 91 



The usual meadow and pasture grasses also do 

 good, if well managed. Where live-stock is pastured 

 on a grass field comparatively little valuable matter is 

 carried off. If the animals are well fed with grain, 

 their droppings may make the soil more fertile. The 

 quantity of both nitrogen and ash ingredients in the 

 surface soil will be considerably increased. That an 

 old pasture ground, when broken up, will usually give 

 a fine corn crop is well known. Permanent pastures 

 are not so common in this country as in Great Britain, 

 the pasture lands here being usually included in the 

 rotation. As a whole, this tends to keep up the fertility 

 of the whole farm. Hay-making and selling is more 

 exhaustive than pasturage, and a continuance of this 

 practice without manuring the meadows is not advisa- 

 ble, but the accumulation of humus and readily availa- 

 ble mineral plant food in the roots and stems of the 

 grass is such that when an old meadow is plowed it 

 frequently gives a good yield of grain, notwithstand- 

 ing the loss of plant food by the sale of the hay. 



Indian corn is now generally thought a less ex- 

 haustive crop than it was formerly believed to be. 

 The longer period of growth, as compared with the 

 small grains ; the fact that it can make use of nitrogen 

 supplies made available during the summer and early 

 autumn; the fact that it has abundant, wide -spreading 

 and deep running roots, and the fact, that, in many parts 

 of the country, only the grain is removed, the stalks, 

 leaves and husks being left on the ground, help ex- 

 plain why it does not decrease fertility so rapidly as 

 its large yield might suggest. 



Oats are popularly supposed to be exhaustive, but 

 the oat crop is the one crop the application of ma- 



