CLOVERS.
Grasses include the cereals, the bread plants of the world. Because they furnish rich food in both forage and grain, these plants are great soil rob bers. They give back little or nothing. The farmer must constantly fertilize his fields, or the yield of grain falls off deplorably. Nitrogen is the most needed element. It can be bought in chemi cal form and spread on the land, plowed or allowed to wash in, and the crop will reward the farmer by increased yield. But this form of nitro gen is expensive. It averages Is cents a pound — a high price to pay.
By planting some nitrogen-gathering plant in rotation with his grain crops, the farmer puts nitrogen back into the soil at a merely nominal cost. Clover is one of the best soil restorers. It is a nutritious pasture, or hay crop. Its roots go deep and pulverize the soil. They gather nitrogen and store it in nodules along their fibrous branches. When growth ceases, the hay is cut and put into the barn; those nitrogen-laden roots are left to decay and enrich the soil for future crops. The surface crop is worth much, for its nitrogenous content is high, and when animals fatten on it, much of its value is twice saved by careful spread ing of the stable manure on the fields.
Four fifths of the air is nitrogen. Clover plants have power to gather this element and store it in the nodules on their roots.
Long before farmers had ever seen the tubercles on the roots of legumes (pod-bearing plants) they knew that clover was the best means of renewing worn-out land and enriching any soil. Fortu nately, experience was their guide, though, until very recently, they followed blindly. One of nature's best gifts to agriculture is this group of plants that constantly renews the soil's fer tility.
Two hundred species of the clover are known to botanists. The hairy, red clover we know as a hay and seed crop, that may be cut early for hay and late for seed the same season. In pasture it "runs out" in two or three years. The mammoth red is an improved kind.
This is not a bee pasture, as the white clover is, because the tubes of the little flowers are too deep for the honey-bee's tongue to reach the sweets.
The bumble-bee has a longer tongue, and by this insect the pollen is carried that insures a heavy yield of seed.
The bumble-bees are very scarce in June, when the red clover comes into bloom. In late summer the clover fields swarm with these insects. Hence, the farmer makes hay in his clover field in June, cutting the succulent stems when they are in the right condition to make the best hay, which is too early for any seed to be ripe. In late summer he sacrifices the quality of the forage to get his clover seed at the time that is ripe. He owes this heavy crop to the bees, though he may not know this, any more than they do.
Alsike, or Swedish clover, grows well on land too wet for the red clovers, and makes superfine hay, pasture, and honey. Its small heads are white, with a tinge of rose. Its stalks are slender and branched. The honey-bees have no trouble in getting the nectar.
White clover creeps into pastures of grass, and lifts its small, white heads on long, unbranched stems. It is wild all over this northern half of the United States, and nobody pays much attention to it, as a rule.
The most beautiful species is the crimson clover, with long, crimson heads on slender, tall plants. It is used as a cover crop in orchards, and as forage, but is not a heavy crop. So it is less frequently sown than other kinds. It grows wild in parts of southern Europe, and is a staple forage crop in parts of Italy.
Berseem, the yellow-flowered clover of Egypt, is one of the plants recently introduced that promises well as a forage crop for dry regions and unprom ising alkali soils.
Clovers will not thrive on sour soils. Such must be sweetened with applications of lime. There must be phosphorus and potash added. Then the roots pasture greedily, plow the soil, unlock the mineral foods the earthy particles hold, and make the soil swarm with nitrogen-gathering bacteria, so that it is literally alive: