Fertilizers and Shade-crops 199 



practice is new. The system of cover-crops as advocated 

 in the East will not apply to the arid regions, for various 

 reasons. We cannot plant in the fall and expect to get 

 much growth to plow under in the spring because of the 

 short seasons. Then it might not be advisable to irrigate 

 at the particular time the seed should be sown, as would 

 probably need to be done to insure germination. We 

 have also found that fall-plowing is better suited to our 

 conditions than spring-plowing, particularly if a crop or 

 manure is to be turned under. If a mass of vegetable 

 matter is plowed under in the spring, the ground is likely 

 to remain so porous that difficulty is experienced in irri- 

 gating. The ground at the upper end of the row soon be- 

 comes saturated, but still a large head of water must be 

 used to force it through to the lower end. Naturally 

 the trees at the upper end are injured. Finally, we think 

 that both land and trees will be benefited by keeping the 

 surface of the soil shaded in the heat of the summer. 



In the light of our present knowledge it will probably 

 be the best plan to prepare the land fairly early in the 

 spring and sow the seed at that time. Or, if experience 

 shows that we need a certain amount of spring tillage in 

 order to aerate the soil and to promote soil activities, the 

 planting may be delayed until June. 



Whether, in the case of perennial shade-crops, it will 

 be best to let them occupy the land for two seasons, plow- 

 ing them under the second fall or not, must be deter- 

 mined by experience and individual conditions. It now 

 seems best to plow the land at least every second season. 

 All of the land may be occupied by the crop in old orchards, 

 but with younger trees space must be left for irrigation as 



