HORTICULTURE 43 



The conditions most favorable for the unlocking of this food and ren- 

 dering it available are the presence of air, carrying as it does free 

 oxygen, and carrying also carbonic acid gas, which is indirectly a 

 very powerful solvent. Thus the systematic aeration of the soil favors 

 its breaking down and increases the ratio of available plant food 

 This aeration may be accomplished in two important ways: One, 

 by systematic tillage, another by keeping up the supply of vegetable 

 matter. Humus or vegetable matter keeps the soil open and porous, 

 so that the air may circulate freely, and in addition, through the de- 

 caying of organic matter, liberates a large quantity of carbonic acid 

 gas, which it is just learned is effective in unlocking plant food. 

 Humus also assists in maintaining a more uniform water content in 

 the soil, preventing it from becoming water-logged for long periods 

 after a rain and preventing it from drying out to that point where 

 very little or no chemical changes occur. 



In soils deficient in humus this dry condition occurs as a rule in 

 midsummer, when the temperature and other conditions are naturally 

 most favorable to the breaking down of the soil, and at the same time 

 when the trees are carrying the maximum of fruit and when they 

 stand in greatest need of a copious supply of moisture and plant 

 food. And eVe~n if the trees are not carrying fruit, they need food 

 at this time of the year to mature the growth they have started in the 

 spring and to fill out and perfect the fruit buds they have formed, in 

 order that both wood and buds may be in good condition for the suc- 

 ceeding winter. (Mo. E. S. Cir. 22.) 



Manuring the Orchard. In manuring the orchard one object 

 is to get a maximum crop. The crop that is up to or possibly just 

 below the average is seldom a profitable one. It is generally inferior 

 in quality as well as lacking in quantity. Its defective character 

 lowers it to such extent that it is brought in competition with the 

 crops of all the poorest cultivators and must be sold often in a glutted 

 market and usually to those who have small means with which to 

 buy. (U. S. E. S. B. 178.) 



In the case of such disastrous drouths as in 1901, it is always the 

 neglected and underfed orchard that suffers most. It is likewise true 

 that underfed trees fall a victim to the attacks of borers, aphis, root 

 rot, etc., much more readily than those that are well nourished. As 

 in the animal kingdom, it is the starved animal that carries all the 

 parasites known to the kingdom, whereas, sleek, fat, well fed animals 

 escape their ravages. When an unfavorable season finds an orchard 

 well set with fruit the fact as to whether it has been well cultivated 

 and is well nourished or not, in other words, as to whether there is 

 present a reasonable supply of available plant food in the soil, exerts 

 a profound influence upon the effect of this unfavorable season upon 

 the crop and upon the life and vitality of the trees. (Mo. E. S. 

 Cir. 22.) 



The elements that enter into the composition of fruit crops are 

 the same as those of farm crops. Although they differ somewhat in 

 their relative proportions one need not be particular, in fertilizing an 

 orchard, to compound the manures exactly according to these pro- 



