ALFALFA 187 



it has been recommended to top-dress alfalfa fields 

 with farmyard manure every autumn. This, no 

 doubt, would prove very effective, but it would also 

 be very expensive, unless in the neighborhood of 

 large cities. It would be impracticable without neg- 

 lecting the needs of the other crops of the farm. 

 In the mountain areas of the West, it has been 

 found that the cost of fertilizing with farmyard 

 manure is in the meantime greater than the in- 

 creased production in the alfalfa is worth, but it may 

 not be always thus, even on these rich lands. Some 

 Eastern growers also apply more or less gypsum. 

 This is generally sown over the fields after the 

 crop has begun to grow in the spring. 



Renovating alfalfa fields is much more easily and 

 effectively done, as would naturally be expected, in 

 areas where conditions are highly favorable to its 

 growth than where these are only moderately favor- 

 able. In some of the mountain valleys instances 

 have occurred in which alfalfa fields have been 

 plowed and sown with oats, with a result, first that a 

 good crop of oats was reaped, and second, that 

 fairly good crops of alfalfa were harvested the fol- 

 lowing season without resowing the field. 



Sources of Injury to Alfalfa. — Chief among the 

 sources of injury to alfalfa, after the plants have 

 become established, are frost in saturated ground, 

 ice, floods, grasshoppers, gophers, dodder, and pas- 

 turing by live stock in the late autumn or winter. 

 When it happens that two or three of these act in 

 conjunction, the injury following is just so much 

 more rapid and complete. As has been intimated, 



