HORTICULTURE 



45 



water. It is probably fair to assume that the weight of the new growth 

 of wood of a thrifty apple tree at fifteen years of age is 50 pounds per 

 year, from which the amount of plant food used for the wood each 

 year can be readily computed. It is also safe to assume that the 

 amount of plant food yearly set free in the soil is sufficient to take 

 care of this growth of wood. The leaves are returned to the soil and 

 hence the manurial material in them does not have to be supplied to 

 the soil. If therefore enough plant food is supplied to replace the 

 manurial ingredients that were taken away from the land in the crop 

 harvested, the land will be maintained in good condition. There is 

 nothing very exact about the amount of manurial material removed 

 each year as it will vary with the soil, the variety of crop, and other 

 conditions. 



The following table shows approximately the amount of plant 

 food materials removed in one year from the soil of an acre of land 

 fully stocked with thrifty fruit trees of the kinds named. This in- 

 cludes the amount contained in the new wood, foliage, and fruit : 



The following table shows the amount of nitrogen, phosphoric 

 acid, and potash found in a good crop of fruit grown on 1 acre : 



This nutrition may be supplied in many forms. Maynard gives 

 the following formulae : (a) For fruit trees over ten years of age (40 

 trees) varying in quantity according to the condition of the soil and 

 crop, 250 to 500 pounds of fine-ground bone ; 100 to 300 pounds of 

 sulphate of potash; 50 to 150 pounds of nitrate of soda. (6) Hard- 

 wood ashes at the rate of 2 tons per acre and the same amount of fine 

 ground bone, (c) South Carolina rock, 400 to 600 pounds, ground 



