Elements Of Fertility

Three elements are necessary for the growth of

apple trees, nitrogen, phosphoric acid, and potash. To these lime may

be added, although its benefit is indirect rather than direct as a

plant food. How badly any of these elements may be needed depends on

the soil, its previous treatment, and on the system of management. By

learning what are the effects of these elements on the tree and fruit

we may determine under what conditions, if any, their use is

advisable.



Nitrogen promotes the growth of new wood and leaves, giving the latter

a dark green color. In fact the color of the leaves and the amount of

the wood growth are usually good indicators of the need of nitrogen.

Nitrogen in excess develops over vigorous growth and prevents the

maturity of wood and buds. It always has a tendency to delay the

maturity of the fruit by keeping it growing late. On many varieties it

tends to produce poorly colored fruits.



When trees are making a normal amount of growth in a year--say a foot

to three feet or more--and when the leaves are of good size and a

dark green in color, there is little need of nitrogen. But when trees

are not growing satisfactorily and the leaves have a sickly yellow

color, then the need of nitrogen is evident. On early soils and in

long growing seasons nitrogen may be more freely and safely used than

under other conditions.



The effect of phosphoric acid and potash on the tree and fruit is much

more uncertain. They are supposed to influence the quality and the

flavor of the fruit, giving better color and flavor, and this they

undoubtedly do to some extent. Potash probably gives the leaves a

darker green color. The precise effect of these two elements is at

present a subject of much discussion, one set of investigators

maintaining after a long and careful investigation that these effects

are too small to be worth while, and the other claiming that they have

a marked effect in the ways above indicated. The only safe guide is

the actual local result. If the fruit is satisfactory in every way it

will be of little use to try fertilizers. On the other hand, if it is

not, then it will pay to experiment with them. The needs of and the

results on different soils are so variable that it is always wise to

experiment on a small scale before using fertilizers extensively.