LUTHER BURBANK 



chard sap the ground and take the nourishment 

 that the tree imperatively needs. But if the sur- 

 face soil is turned under this vegetable matter will 

 in itself constitute a fertilizer. Unless the soil is 

 unusually rich this should be supplemented with 

 artificial fertilizers, of which nitrates, phosphates 

 and complete mineral fertilizers often appear to 

 have the best effect in rejuvenating an old orchard. 



In case the soil is a sandy loam, subject to rapid 

 leaching, it may be desirable to sow a so-called 

 "cover crop" to prevent the too rapid washing 

 away of the plant foods in the rainy season. If a 

 leguminous crop is grown, such as clover, crimson 

 clover, cow peas, or vetch, these crops will in them- 

 selves add to the nitrogen of the soil, as their roots 

 have the power of taking this from the air. But 

 it is urged by some eastern -orchardists that care 

 should be taken to avoid too much nitrogen. The 

 roots of the tree reach down to rich subterranean 

 sources that are likely to be well supplied with 

 nitrogen, because the nitrates are very soluble and 

 are pretty rapidly leached or filtered into the sub- 

 soil. 



After preliminary treatment it has been found 

 in many states best to sow a crop of clover, often 

 with other perennial grasses, as a permanent crop, 

 which should be cut and all material left on the 

 ground for the protection and support of the or- 



[48] 



