49 



liand, Avlierc but little stock is kept, and esjiocially wlici-c the 

 production of apples, peaches or other tree fruits is an im- 

 portant part of the farm business, the clovers are among the 

 most valuable crops which can be used for cover, to supply 

 humus, and to enrich the soils in nitrogen. It is now gencr- 

 allv undcM'slood that under right conditions clovers are capa- 

 ble of taking the nitrogen which they need from the air. In 

 this respect the clovers and the other plants of the clover fam- 

 ily are superior to any other crops which can be used for 

 similar 2)ui'poses. It is, then, this single fact, that the clovers 

 can take the nitrogen they need from the air, while crops of 

 other families cannot do this, which renders them so much 

 more valuable than most other crops for cover and green 

 manuring. It is the purpose of this article to consider es- 

 pecially clovers as forage crops. A brief statement of the 

 principal reasons for their great value as such may be useful. 

 1. The cost of manures and fertilizers needed to produce 

 them is low. As has just been stated, the clovers under the 

 right conditions take their nitrogen from the air. They draw 

 upon the soil simply for the mineral constituents of plant 

 food, such as lime, phosphoric acid, potash and magnesia. 

 These mineral elements of plant food are relatively abundant, 

 and can be purchased at comparatively low prices. Nitro- 

 gen, on the other hand, if purchased in the form of either 

 manure or fertilizers, will usually cost from IG to 18 cents 

 per pound. Phosphoric acid and potash cost only 3 to 5 

 cents per pound, the price varying according to the material 

 selected. Lime and magnesia cost still less. The latter, in- 

 deed, need seldom be purchased, for it, as well as the other 

 mineral constituents found in plants, is almost invariably 

 sufficiently abundant in all soils. Striking evidence that the 

 manurial cost of producing clovers is low is afforded by the 

 results in one of the fields of the Hatch Experiment Station. 

 A plot in this field was manured annually for fifteen years 

 at the following rates per acre: dissolved bone-black, 820 

 pounds; and muriate of potash, 160 pounds. The crops 

 raised on this field, in the order of their production, were as 

 follows: corn, corn, oats, hay, hay, corn, rye, soy beans, white 

 mustard, corn, corn, hay, hay and corn. The hay croj^s have 



