The speed of soil destruction, with its erosion after plowing, is particularly noticeable with the great American crops, cotton, corn and tobacco, which require clean cultivation. Many orchards are also cultivated for the double purpose of keeping down rival plants and preserving moisture, but we pay high in soil loss for the moisture that we get by that means on hilly lands. The plow is one of the greatest enemies of the future. As a matter of fact we have already destroyed enough land in the United States to support many millions of people; and therefore the tree is the more important because it permits an agriculture that will keep the soil indefinitely, and in permanent production, without plowing.
I have aecidently discovered a better way of conserving moisture than by plowing, and I have found it going on in widely scattered places and in widely different climates.
Primitive peoples in many parts of the world have long since obtained the advantage of cultivation, mainly, increasing the available moisture for the tree or plant, without cultivation of the soil and the loss which follows the washing of cultivated soils. As an example I cite the Indians of Arizona, who have grown corn crops for centuries in a country with but from six to fifteen inches of rain. They do this by planting in little patches at the mouth of a gully where at the time of rain the flood water is led away into furrows and depressions so that it thoroughly soaks the ground in which the corn is planted.
My attention was first called to this practice by observing a good patch of barley in the edge of the Sahara in Southern Tunis, where the gulley flow resulting from a winter rain had spread itself out fan-*like and soaked the triangular alluvial area of sand, which bore a fine crop of barley in the midst of the desert.
For centuries the olive growers of parts of Tunis have led gulley water to the olive trees where it was retained, in areas that resembled a tennis court, with a 12 inch bank of dirt around it and two or three olive trees within this area thus watered by impounding.
A practice somewhat similar to this is shown in F. H. King's classic book on Chinese agriculture, "Farmers of Forty Centuries;" but the most extreme case that has come to my attention is furnished by the Berber tribe of the Matmatas, of Tunis. These people live on the edge of a hilly, limestone plateau, where the rainfall is less than 10 inches and in some years as low as five.
An important part of the food supply of these people is furnished by date and olive trees which they grow in the gulches of their limestone plateau. They built a dry rock dam behind which earth-wash lodges. In this the trees are planted and every rain sends more earth and soaks that which has collected. The plan can certainly not be called an experiment for the people have lived there for centuries. They have olive trees that are several centuries old and I have never seen such fine olive trees, not in California, or the plains of Spain, Portugal, France, Italy, or in Algeria or Tunis, and I have seen a good many olive trees in those countries. The olive tree is usually open, light and feathery. These in the Matmatas gulches are thick and black and rank.
For automatic cultivation and fertilization the plan of these primitive agriculturists is hard to beat. You put up your stone dam, and every time the gulley runs with water your crop is irrigated and fertilized. Can you beat it?
Three Americans of my acquaintance have independently experimented and discovered along similar lines.
The late Freeman Thorpe of Hubert, Minnesota, did it with much enthusiasm. So did the late Dr. Meyer, a friend of J. F. Jones, near Lancaster. He discovered it accidentally. He put a brush dam across a gully. Water stood behind it for days after every rain. The apple tree near it grew much more than the others. That started the Doctor. He began to dig small field reservoirs and collect water near trees and he found that it paid even with the very expensive process of hoe and shovel.