Fig. 234. Cowpeas
If this crop is grown for hay, the method of seeding and cultivating will differ somewhat from the method used when a seed crop is desired. When cowpeas are planted for hay the seeds should be drilled or broadcasted. If the seeds are small and the land somewhat rich, about four pecks should be sowed on each acre. If the seeds are comparatively large and the soil not so fertile, about six pecks should be sowed to the acre. It is safer to disk in the seeds when they are sowed broadcast than it is to rely on a harrow to cover them. In sowing merely for a hay crop, it is a good practice to mix sorghum, corn, soy beans, or millet with the cowpeas. The mixed hay is more easily harvested and more easily cured than unmixed cowpea hay. Shortly after seeding, it pays to run over the land lightly with a harrow or a weeder in order to break any crust that may form.
Mowing should begin as soon as the stalks and the pods have finished growing and some of the lower leaves have begun to turn yellow. An ordinary mower is perhaps the best machine for cutting the vines. If possible, select only a bright day for mowing and do not start the machine until the dew on the vines is dried. Allow the vines to remain as they fell from the mower till they are wilted; then rake them into windrows. The vines should generally stay in the windrows for two or three days and be turned on the last day. They should then be put in small, airy piles or piled around a stake that has crosspieces nailed to it. The drying vines should never be packed; air must circulate freely if good hay is to be made. As piling the vines around stakes is somewhat laborious, some growers watch the curing carefully and succeed in getting the vines dry enough to haul directly from the windrows to the barns. Never allow the vines to stay exposed to too much sunshine when they are first cut. If the sun strikes them too strongly, the leaves will become brittle and shatter when they are moved.
When cowpeas are grown for their pods to ripen, the seeds should be planted in rows about a yard apart. From two to three pecks of seeds to an acre should be sufficient. The growing plants should be cultivated two or three times with a good cultivator. Cowpeas were formerly gathered by hand, but such a method is of course slow and expensive. Pickers are now commonly used.
Some farmers use the cowpea crop only as a soil-enricher. Hence they neither gather the seeds nor cut the hay, but plow the whole crop into the soil. There is an average of about forty-seven pounds of nitrogen in each ton of cowpea vines. Most of this valuable nitrogen is drawn by the plants from the air. This amount of nitrogen is equal to that contained in 9500 pounds of stable manure. In addition each ton of cowpea vines contains ten pounds of phosphoric acid and twenty-nine pounds of potash.
There is danger in plowing into the soil at one time any bountiful green crop like cowpeas. As already explained on page 10,[**ref] a process called capillarity enables moisture to rise in the soil as plants need it. Now if a heavy cowpea crop or any other similar crop be at one plowing turned into the soil, the soil particles will be so separated as to destroy capillarity. Too much vegetation turned under at once may also, if the weather be warm, cause fermentation to set in and "sour the land." Both of these troubles may be avoided by cutting up the vines with a disk harrow or other implement before covering them.
The custom of planting cowpeas between the rows at the last working of corn is a good one, and wherever the climate permits this custom should be followed.
Vetches. The vetches have been rapidly growing in favor for some years. Stock eat vetch hay greedily, and this hay increases the flow of milk in dairy animals and helps to keep animals fat and sleek. Only two species of vetch are widely grown. These are the tare, or spring vetch, and the winter, or hairy, vetch. Spring vetch is grown in comparatively few sections of our country. It is, however, grown widely in England and northern continental Europe. What we say here will be confined to hairy vetch.
After a soil has been supplied with the germs needed by this plant, the hairy vetch is productive on many different kinds of soil. The plant is most vigorous on fertile loams. By good tillage and proper fertilization it may be forced to grow rather bountifully on poor sandy and clay loams. Acid or wet soils are not suited to vetch. Lands that are too poor to produce clovers will frequently yield fair crops of vetch. If this is borne in mind, many poor soils may be wonderfully improved by growing on them this valuable legume.