ALFALFA IN CROP ROTATION I9I 



for the growth above. These first smaller roots decay 

 and others start out from the taproot lower down. 

 These decay and still others start. The decaying roots 

 add humus to the soil, and the openings left by them form 

 a wonderful system of channels for the penetration of 

 air and water into the soil. The erstwhile compact earth 

 is honeycombed and air and water penetrate the graves 

 of the dead roots until, when the alfalfa field is ready to 

 be used for a different crop, the soil has been wonderfully 

 changed not only in its chemical elements but in its physi- 

 cal character. 



5. The regular deposit of alfalfa leaves, from the 

 cuttings, under the best care, has been estimated at one- 

 half ton or more per acre every year. As these leaves 

 contain a great percentage of protein, it can readily be 

 seen that they make a heavy contribution to the soil's 

 fertility. 



VALUE OF STUBBLE AND ROOTS 



When in his system of rotation the farmer is ready to 

 plow up his alfalfa, he has another inestimable contribu- 

 tion to the land's fertility in the stubble and roots. It is 

 not recommended to plow under any considerable growth 

 as a green manure, as the hay crop is too valuable. Its 

 market value would buy more fertilizers than the same 

 growth is worth for humus. After a field has stood for 

 five or six years, the roots have added largely to the 

 humus content. Prof. W. P. Headden of Colorado, esti- 

 mated that the fertilizing value of the stubble and 6^ 

 inches of roots plowed under is about $20 per acre, while 

 the value of the stubble and entire root system is not less 

 than $35 per acre. 



