The use of cover-crops in orcharding marks a specific advance brought about by changed soil conditions. The term is less than 10 years old, having been first applied in this connection by Bailey, in Bulletin 61, Cornell (N. Y.) Experiment Station, p. 333, December, 1893, though cover-crops were used previous to that date.
In the early days of orcharding in this country, the soil, rich in humus and undepleted of its natural resources, gave satisfactory crops of fruit with trees growing in sod. As time went on, the waning vigor of the trees was stimulated by breaking up the sod, adding barnyard manure to the soil and giving thorough cultivation throughout the season.
This system gave unsatisfactory results in many instances, particularly in the north, as it appeared to prevent the trees from ripening their wood sufficiently to enablethem to endure the winters without frost-injury to the tips; root-killing was also noted as being occasionally severe on soils uncovered with vegetation during the winter. About this time the value of the members of the pea and bean tribe, as enrichers of the soil, became recognized more fully than formerly through the discovery of the nitrogen-collecting agents housed in the nodules borne by the roots of legumes.
The best orchard practice of the present day, whether in the peach growing areas of the south or the apple districts of the north, consists in giving the most thorough cultivation possible during the wood-producing period of the year,—that is. till about the time the fruit trees’ terminal buds are formed,—then seeding this thoroughly pulverized surface with a suitable cover-crop, which is lowed under early the following spring.
Cover-cropping is the raising of a crop in the orchard after cultivation should cease (about midsummer), that will protect the roots of the trees by preventing alternate freezing and thawing and deep freezing of the ground; that will add something to the fertility of the soil when turned under in spring; that will improve the physical condition of the soil; that will occupy the ground to the exclusion of weeds. In the south, the considerations are practically identical, except that the contingency of root injury from frost is not weighed.
There are two classes of cover-crops: the nitrogenous and the non-nitrogenous. Of the former, rye, buckwheat, oats, millet, corn (maize), rape and turnips are principally used. These plants should be sown much later in the season than the clovers, cowpeas or most nitrogenous covers. They are valuable where the soil is hard and tough in texture, as advance agents of the legumes which may be used when an improved physical condition is so cured.
Buckwheat is particularly useful in ameliorating hard soils. It should not be sown early enough to allow seed to form before frost. These add comparatively little nitrogen to the soil. Among nitrogenous cover-crops, crimson clover, red clover, cowpeas, soybeans, field pea, and vetch are the most prominent. In the south, crimson clover and cowpea (of which there are many varieties) are much in vogue. Cowpeas are unsatisfactory, however, north of the peach belt, owing to their sensitiveness to light autumn frosts.
In apple growing sections where the soil is mellow, red clover does well. A mixture of crimson clover and oats is used in peach sections in Michigan with success; 12 quarts of the former to 3 pecks of the latter per acre are sown about the middle of August. The Geneva Experiment Station recommends a mixture of 56 bushels of buckwheat to 1 bushel of field peas per acre for clay soils.
The question of what cover-crops to use is best determined by an examination of the character of the soil, and the condition of the orchard trees. If the trees are growing slowly on mellow and friable soil, it will probably be advisable to use a nitrogenous cover-crop. If, on the other hand, the trees are making a luxuriant growth, and the soil is of the heavy order, a member 0! the non-nitrogenous group should be tried.
Kinds of Cover-crops.
l. Non-nitrogenous ll. Rye, two bushels per acre. b. Buckwheat, ‘/,1 bushel per acre. c. Outs, 2% bushels per acre.
1!. Corn, broadcast 1 bushel per acre. 0. Rape or turnips, 3 pounds per acre.
2. Nitr0genous— a. Crimson clover, 16 pounds per acre.
11. Red clover, 14 bushels per acre. 1:. Sand vetch, 1% bushels per acre. d. Soybeans, 2 bushels per acre. e. Cowpeas, 2 bushels per acre. I. Field peas, 1% bushels per acre.
3. Mixtures of Nos. 1 and 2
a. Buckwheat, 1% bushels per acre. Field Peas, 1 bushel per acre. II. Crimson clover, 12 pounds per acre. Oats, three peeks per acre. c. Oats, 1 bushel per acre. Votch, 1 bushel per acre.