Peas as a Field Crop
by J.L. Stone, circa 1911
Some people find them inconvenient, but I do enjoy throwing field peas into the seed mix with nurse crops as they add nitrogen to the soil and goodies to the hay. LRM
The pea is grown as a field crop for the production of grain for stock-feeding and for the manufacture of “split peas” for culinary use, for canning in the factories, for forage and green-manuring and to supply the seed trade.
The pea is the most important member of the genus Pisum. It is native to Europe, but has been cultivated from before the Christian era for the rich seeds. It is an annual, glabrous and glaucous, tendril-climbing; the stipules are large and leafy; the leaflets are oval or ovate, two to three pairs, the leaf ending in tendrils; the flowers are few, on an axillary peduncle. The field- or stock-pea differs from the garden pea usually in its violet or purple rather than white flowers, its smaller and more uniformly smooth seeds, but chiefly in the less tenderness and sweetness and lower quality of the green seeds.
The pea is generally supposed to be a native of southern climates and was well known both to the Greeks and to the Romans, frequent mention being made of it in the works of old writers on rural subjects. A form of gray pea still growing wild in Greece is supposed by some to be the original form of all the highly domesticated varieties belonging to the species. The pea has been known and cultivated in England for centuries. Most of the early English writers on agricultural topics mention it either as a garden vegetable or as a farm crop. Lydgate, a writer in the time of Henry VI, speaks of peas as being hawked about the streets of London. It seems to have been more extensively used as a garden vegetable in England before the introduction of the potato than during recent years.
In the United States the practice of canning green peas, thus rendering them available throughout the year, has led to their being extensively used by the well-to-do classes. The area now devoted to canning peas very largely exceeds that planted to stock-peas.
Peas thrive best in localities having somewhat cool summer temperatures and a rather abundant supply of moisture. For grain and seed production the southern parts of Canada and the northern belt of the United States seem to be best suited. Farther south fruiting is less certain owing to liability to hot weather, though the crop may have value for forage and green-manuring purposes.
Peas may be grown successfully for green-manure or forage purposes in many regions where climatic conditions are not favorable for a good yield of seed, and they may be raised successfully for canning or marketing in the green state where, because of insect infestation, the matured seed is of little value.
The varieties of peas are numerous and are of two general classes: the field-peas, grown for stock food and for the production of “split peas” of the markets, and the sweet, wrinkled or vegetable peas grown largely for canning and for consumption in the green state. The field varieties in the United States are usually classed together as “Canada field peas.”
Of the vegetable peas there are many varieties. They differ from the field sorts principally in containing more sugar, which increases palatability, and many of the varieties have wrinkled seeds while the field sorts are smooth. The wrinkled varieties usually produce white flowers, while the smooth sorts have colored (mostly purple) blooms. They vary greatly in habit of growth, being dwarf or large; early, medium or late; and in quality, from moderately to very sweet. Many of the dwarf, early varieties are smooth and only moderately sweet, while the late, large varieties are wrinkled and much sweeter.
Soils. – For whatever special purpose the pea crop may be grown, the general soil and cultural requirements are much the same. The crop succeeds on a variety of soils. Clay loams, especially if well supplied with lime, are best adapted, but excellent crops are grown on stiff clays. Light, sandy and gravelly soils are not so suitable, as they are liable to dry out and become hot. Mucky soils produce a large growth of vine but the yield of grain is likely to be small. While peas require an abundance of moisture for their best development, over-wet soils are wholly unsuited to the crop.
Preparation of the land. – Fall-plowing is to be recommended for peas. This favors early sowing the following spring, which is desirable, and exposes the stiff soils, on which peas are usually grown, to the ameliorating influences of the winter’s freezing and thawing. It is desirable that the land be well pulverized, but, since the pea is a hardy and vigorous grower this is not so necessary as for the small grain crops.
Fertilizing. – When grown on poor soils, peas respond well to manure or fertilizers, but on soils of good fertility the manures are usually applied to other crops in the rotation and fertilizers are rarely used. Some growers maintain that if manure is applied it should be plowed under deeply, so that the tap roots will reach it during the seed-forming period.
Place in the rotation. – Peas may be assigned any place in the rotation. When properly inoculated they are capable of gathering nitrogen from the atmosphere and consequently are not so dependent as some other crops on nitrogen supplied by decaying grass and clover roots. Still, an inverted sod is found in experience to produce the best of yields, and the pea crop is most excellent to break down the sod and prepare the land for exacting grain crops, such as wheat. The usual practice, however, is to have peas follow a tilled crop, as beans or corn, and then be followed by wheat. A farmer can almost afford to grow a crop of peas for the purpose of fitting the land for wheat.
Seeding. – Peas are usually sown with a grain drill or broadcasted by hand. If the land is very foul with weeds they are sometimes planted in drills twenty-eight to thirty inches apart so as to permit of horse cultivation during the early stages of growth. The grain drill is usually preferred to hand-broadcasting, as it covers the seed more evenly than the latter method. On spring-plowed land the peas are sometimes sown by hand immediately after the plow. The seed falls into the depressions between the furrows and is usually well covered by the harrowing which follows. Some persons have recommended sowing the seed ahead of the plow and turning it under the furrows, but this usually buries it too deeply, especially if the land is rather heavy. The depth of seeding varies from two to four inches, being deeper on the lighter soils.
The quantity of seed required per acre will vary with circumstances from two to four bushels. Rich soils which tend to produce a vigorous growth of vine require less seed than poorer soils. Large-seeded varieties or those producing small vines require more seed per acre than those having small seeds or producing large vines. Usually the canning varieties require heavier seeding than those grown for stock-feeding.
Harvesting and threshing. – Peas are usually cut with a mowing machine. The tendency of the vines to fall on the ground often makes the cutting a difficult task. Sometimes extra long guards of special shape are provided which lift up the vines so that the knives may cut them satisfactorily (called pea-lifters). Following the mower, men with forks pitch the cut peas to one side in bunches so that they are not trampled on at the next bout.
A pea harvester constructed on the plan of the twine binder has recently been invented. It does not bind the peas, but delivers them at the side out of the way, and thus saves the extra labor of moving them by hand.
If the crop has been matured for seed or grain purposes it is allowed to cure in these bunches, which are turned once or twice to facilitate drying. When dry, peas may be stored in a barn or stack like other grain. As the pea-straw will not shed rain well, stacks should be topped with some finer material to protect the crop from damage.
If the crop is grown for canning purposes it is drawn to the factory immediately after being cut. Formerly it was customary to pick the pods containing the peas by hand-labor in the fields and deliver these only at the factory, but more recently the difficulty of securing sufficient laborers to do this work and the introduction of pea threshers that successfully shell and separate green peas from the vines has led to delivering the whole crop to the factory.
Peas are usually threshed by machinery, though when only a small quantity is grown annually they may well be threshed by using a flail. This avoids breaking the seed. In handling larger quantities, machine threshing becomes advisable. A “bar concave” with most of the spikes removed is best, and the cylinder should be run at a low rate of speed to avoid splitting the peas as much as possible. If the grain is intended for stock-feeding the amount split is unimportant, but when intended for seed or the market the breaking of the grain lessens its value. The regular bean thresher does more satisfactory work on peas than the ordinary grain thresher.
The general method of pea-culture outlined above is applicable whatever may be the intended use of the grain. The varieties to be planted will vary with the purposes for which they are grown.
Stock-feed. – The uses of the pea crop are numerous. In Canada it is much more largely grown as a general farm crop than in the United States. The grain has a high feeding value owing to its relatively high content of protein. As part of the grain ration of horses, fattening cattle, milch cows, sheep and swine, peas are unexcelled. When fed to sheep or brook sows in winter, peas do not require to be ground. For all other stock it is advantageous to grind them, though sometimes they are soaked in water for feeding to swine. When intended for stock-feeding, peas are frequently grown with oats. The combined crop will usually have a greater total value than would be produced by either alone. When so grown, about one and one-half bushels of oats should be sown with one bushel of peas per acre.
Pea-straw, if well cured, is more relished by horses, cattle and sheep than the straw of other grain crops. Indeed, if not allowed to become too mature before cutting, nor weather-beaten in the curing, it more nearly approaches clover hay in nutritive quality and palatability than ordinary straw.
Peas sown with oats or barley afford excellent pasturage for sheep and swine, but unfortunately produce best growth at the season when the grass pastures are at their best. For large stock such pasturage is not so satisfactory, as the peas are easily injured by the tramping of larger animals. Sown in this way and cut just before the peas are full-grown, they produce an excellent soiling crop, and are much used to bridge over the interval between the shortening up of grass pasture and when corn is ready for use. By sowing at intervals of ten days, a supply of green forage may be provided for several weeks. Any surplus not needed for green forage may be cut and cured for hay.
In common with other leguminous plants the pea is especially rich in protein, and much of its agricultural value is due to this fact. The following table gives approximately the digestible nutrients in the products named:
Soil enricher. – Since peas, like other legumes, have the power of obtaining nitrogen from the atmosphere and placing it within reach of other plants, they are much used in some places as a green-manure crop. Some persons assert that land from which a crop of peas has been harvested is richer in nitrogen than it was before the crop was grown. Peas are frequently used for sowing in apple orchards, the common Canada field-peas being suitable for this purpose. The orchard is plowed shallow very early in the season and, when the peas are beginning to ripen, pigs are turned into the orchard to harvest the crop, and the larger the pea crop and the smaller the drove of hogs, the longer will the peas last. The principal growth of the peas is made in spring when there is plenty of moisture. The pea crop is made by the middle of July and does not draw on the moisture supply in the orchard after that date, when the moisture is needed by the apple trees.