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.

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