Tombstone epitaph., 1917-04-29


 ment of Agricultural
 From the earliest days of agricul- ture farmers have observed that the clOvers, alfalfa. beans and peas en- riched the soil so that wheat. corn. cotton and similar crops gave better yields following them than when plant ed after the grains or grasses. The reason for this benefit to the soil, how ever, is of recent discovery and the broader practical application of the knowledge is just beginning to be ef- fective.
 leguminous plants are readily dis tinguished. in most instances. by the characteristic form of their flowers. of which the garden pea is typical. and by the seed-bearing pods which split upon ripening, at both edges or su- lures. The most important difference. however, between leguminous and non leSuminOus crop plants as they affect the fertility of soil is the formation of nodules or tubercles. normally at taChed to the roots of thriving plants of the legume family. These nOdules vary greatly in size and shape. On the roots of red clover they are about the size of a pinhead and ovoid in form: on alfalfa they are somewhat larger and irreguler in shape, ire quently forming in egg-shaped masses, the aggregate of which may be the size of very small marble. while on soy beans the nodules resemble the seeds of the common pea both !n size and shape. For many years and until com paratively recent times these nodules were thought to be a form of root-gall disease. In 1886 the scientists He'll riegel and Wilfarth discovered their real function in relation to the plants and to the soil.
 Function of Root Nodules and Noduie
 Bacteria.
 + a nodule on living plant be cut open and some of the juicy substance In 1t be spread thinly upon n glass slide. examination under high power microscope will reveal an i'm mense number of living sinGle-celled organisms of the kind called bacteria These nOdule-forming bacteria. when
  hairs of leguminOus plants during their early growth and establish them selves In the outer layer of cells of the true roots, where they multiply rapidly and form the enlargements called nOdules.
 The nOdule bacteria and the host plant are mutually helpful. The plant furnishes home for the bacteria and the bacteria in turn manufacture food for the plant.
 Plants. like animals, require food materials for growth. Among the most important plant foods are com pounds of the element nitrogen, which as an invisible gas comprises about four-fifths of the atmosphere. Nitro gen cannot be taken in directly by the leaves Of plants as Is carbon diOxid, but must first be combined with other clements to form soluble compounds of nitrogen which can he readily ab- sorbed by the roots. The nodule bac- teria of leguminOus plants use nitro gen directly from the air as. 1t circu- lates in the soil and convert 1t into nitrOgenous compounds which are utl- iized in the growth of the plants.
 NonIeguminous Crops.
 Nonleguminous crops, including corn and other grains. cotton, and the grasses, secure all of the nitrogen for their growth from the soil. All legu- minous crops, under normal conditions, obtain a large part of their nitrogen through bacterial action directly from the air, and in general they contain a larger percentage of nitrogen and con