Sod and tillage have somewhat different effects on the tree and on the fruit. Let us see what these effects are. It is common knowledge that fruit is more highly colored when grown in sod than when grown under a tillage system. This is probably largely due to the fact that tillage keeps the fruit growing so late that it does not mature so well or so early. Fruit is usually two or three weeks later in tilled than in sod orchards. It has been shown that fruit grown under tillage keeps from two to four weeks longer than that grown in sod. It is claimed also—but this is a disputed point—that tilled fruit has a better quality and flavor. Certain it is that fruit grown in sod is drier and less crisp and juicy.
The effect of tillage on the trees is more marked and better known. Tilled trees have a darker, richer green foliage, indicating a better and more vigorous health. The leaves are also larger and more numerous. They come out three or four days earlier in the spring and stay on the trees two weeks later in the fall than the leaves on trees kept in sod. Tilled trees make nearly twice the growth in a season that those in sod do, in fact there is danger of their making wood growth at the expense of fruit buds. Tillage also gives a deeper, better distributed root system.
Despite the advantages and the disadvantages of each system, there are times, places, and circumstances under which one is more advisable than the other. On lands rich in humus and in plant food and level so as to be easily tillable, cultivation is without doubt the best system. But it should be practiced in connection with cover crops, and the orchard should be given occasional periods of rest in sod—say one year in from three to five.
The sod mulch system of orchard culture is probably better adapted to rather wet good grass land and where mulching material is cheap and readily available. It is undoubtedly at its best on lands too steep or rough to till, or otherwise unsuitable to cultivation. Tillage is the more intensive method and where labor is scarce and high sod culture might be more advisable for this reason, other conditions being not too unfavorable.
In order to illustrate a method of management under the tillage system we may suggest the following as a good one for level to gently rolling land:
1912. Early plowing in spring, cultivation to July first to fifteenth. Then sow red clover as a cover crop.
1913. Repeat previous year's treatment, varying the time of sowing cover crop according to conditions.
1914. Let the clover grow, mowing and leaving on the ground as a mulch, June fifteenth to twentieth, and again in August.
1915. Plow early in spring, cultivate to midsummer, and then sow rye or buckwheat as a cover crop July fifteenth to August fifteenth.
1916. Repeat 1915 treatment and if trees are not growing too fast, sow clover or hairy vetch as a cover crop.