Legumes

In general, legumes are more valuable as cover and green

manure crops than non-leguminous plants, because as a rule they are

more rank growers and more deeply rooted, as well as because they add

nitrogen to the soil. But it is rather more difficult to secure a good

stand of most legumes than it is of the crops previously mentioned for

several reasons. As a rule the seeds are smaller and a large seed

usually has greater germinating power than a small one. This often

means much at the time of the year when the cover crop is sown. Then

legumes are more difficult to grow, requiring better soil conditions.

Still these should be present in good orchard soils. Drainage must be

good, the soil must be at least average in fertility and physical

condition, it must not be sour--hence it is often necessary to use

lime--and soils frequently require inoculation before they will grow

legumes satisfactorily.



Where the clovers grow well they make excellent cover crops as well as

green manure crops. The chief difficulty with them is that of

obtaining a good stand in a dry midsummer. The mammoth red and the

medium red clovers are probably the best of their genus on the heavier

soils, while crimson clover is best on sandy soils and where it will

grow, on the lighter gravel loams. The latter is especially well

adapted to building up run down sandy soils. Although it is somewhat

easier to secure a stand of this clover, alsike does not grow rank

enough to make a good cover or green manure crop. Most clovers are

deep rooted plants and therefore great soil improvers physically as

well as being great nitrogen gatherers. The amounts of seed required

per acre for the different kinds are about as follows: mammoth fifteen

to twenty pounds; red (medium) twelve to fifteen pounds; crimson

twelve to fifteen pounds; and alsike ten to twelve pounds.



Where it can be readily and successfully grown alfalfa is really a

better cover and green manure crop than the clovers. It is deeper

rooted, makes a better top growth, and therefore adds more nitrogen

and more humus to the soil than the clovers. It cannot be recommended

for common use, however, as it is so difficult to grow except under

favorable conditions. It requires a more fertile soil than clover, a

soil with little or no acidity, good drainage, and usually the soil

must be inoculated. Only where these conditions prevail can alfalfa be

generally recommended.



Vetch is an excellent cover and green manure crop, forming a thick,

close mat of herbage which makes a good cover for the soil. It is very

quick to start growing and a rapid grower in the spring. It also adds

larger quantities of nitrogen. The hairy or winter vetch lives through

the hard freezing winters. Summer vetch, although an equally good

grower, is killed by freezing. One bushel of seed is required per acre

and the seed is expensive, which is the greatest objection to the use

of this excellent crop.



Two other less well known and used leguminous crops are well worth

trial as cover crops--soy beans in the North and cow peas in the

South. Both are great nitrogen gatherers and as they are rank and

rapid growers add large quantities of humus to the soil. Under

favorable conditions they will cover the ground with a perfect mat of

vegetation in a very short time. Being larger seeded, it is

considerably easier to obtain a stand on dry soils and in dry seasons

than it is of the smaller seeded clovers. It is usually best to sow in

drills the ordinary width, seven inches, apart.



Cow peas are universally used as a cover and green manure crop in the

South, but they do not thrive so well in the North. One and one half

to two bushels of seed are required per acre. In the North the earlier

maturing varieties of soy beans are almost equally good. One to one

and one half bushels of seed are sown per acre.



Leguminous cover crops are also the best and the cheapest source of

nitrogen for the apple orchard, after they are well established. Their

use may be overdone, however. Too much nitrogen results in a growth of

wood at the expense of fruit buds. To avoid this it is often advisable

to use non-leguminous and leguminous crops alternately, when the

orchard is making a satisfactory growth. Sometimes also these two

kinds of crops, as buckwheat and clover for example, may be combined

with good results. When this is done one half the usual amount of seed

of each should be used.