MAINTAINING FERTILITY 255 



severe washing, this system is advisable. Here the grass 

 is cut three or four times a year, and left on the ground or 

 raked under the outer branches of the trees. It thus 

 serves as a mulch to prevent the loss of soil moisture. It 

 is frequently necessary, however, to apply additional 

 straw or coarse manure. Since the plant food on this 

 system is not liberated so rapidly in the soil, it generally 

 becomes necessary to fertilize more heavily than where the 

 soil-mulch system is practiced. In planting trees, the sod 

 should be turned under for a considerable distance around 

 the trees and a heavy coating of straw applied until they 

 have grown sufficiently to shade the ground beneath. 



Maintaining Fertility. Maintaining fertility is one of 

 the serious problems that confront the fruit grower. The 

 general farmer keeps stock enough on the farm to supply 

 fertilizer for his land, but the fruit grower without live 

 stock must find some other method of maintaining the 

 fertility of his fields. Unlike the annual crops of the 

 farmer, a fruit tree grows for years on the same site, draw- 

 ing the same kind of plant food from the soil. 



The purchase of plant food in the form of commercial 

 fertilizers is expensive. The cheapest source of fertilizer 

 for the fruit gardener is the soil itself, but often this plant 

 food is in an unavailable form. Tillage lets in the air and 

 promotes the activity of the soil. It is the cheapest way 

 of making plant food available. 



It is not always sufficient to improve the fertility of an 

 orchard by tillage alone, but it will help much in reducing 

 the amount of fertilizer that need be furnished. When 

 an orchard has been in sod for a number of years, its growth 

 may be stimulated by breaking up the sod and thus liberat- 

 ing plant food. 



