CLOVER AND PEAS. 139 



acid, and the amount of this in a soil gives it its im- 

 mediate productive power. 



While the leguminous plants, such as clovers and 

 peas, also have the power to take nitrogen from the 

 free and uncombined stock in the atmosphere — are 

 nitrogen gatherers — rye and buckwheat have no 

 such power, consequently the former should always 

 be selected in preference to the latter. 



The use of clover offers the most advantages. The 

 clover roots go down into the subsoil, often to the 

 depth of many feet, and here forage for mineral 

 food supplies unavailable for other crops, or out of 

 their reach, and arrest the nitrogen that in the 

 form of nitrate may be ready to escape into the 

 drains, or into the depth of lower strata. All these 

 foods are brought up nearer to the surface, and 

 held there in readiness for use by other crops after 

 the clover has decayed. 



Mechanically, also, clover has advantages not 

 possessed by the other plants named. The lower 

 parts of the roots which are not reached by the 

 plow, and are therefore left to decay 

 cfotir and7.«. ^^ere tliey grow, will leave a multi- 

 tude of little tubes or channels, per- 

 forating the lower stratum like a honey-comb, and 

 allowing the air to pass down freely into the depth 

 of the soil, thereby subjecting it to more rapid 

 changes, hurrying up the decomposition of vege- 

 table matter, and thus adding warmth and promoting 

 healthy growth. 



The only objection to the use of clover as manure 

 crop is the comparatively long period needed for its 

 growth. In peas we have a crop that can be pro- 

 duced in short order, and that will make humus 

 and gather nitrogen from the air, but their roots are 



