Page:Tree Crops; A Permanent Agriculture (1929).pdf/363

 harvest a series of crops with, perhaps, cotton in the series as a cash crop. You plant out most of your farm with pecan trees in rows two hundred feet apart, fifty or one hundred feet apart in the row. This is not much of an interference with plowing, harrowing, planting, or tillage. Save for the cotton and probably some corn you have no harvesting operations; the pigs do that and little trees do not interfere with them. Little trees do not interfere with harvesting cotton or corn.

After you have planted your pecans, walnut, hickory, honey locust, grafted oak, or other large-growing productive trees as just described, you go on with the hogging-down crop rotation. Gradually the trees grow to gigantic size and maximum productivity, meanwhile the hog farming goes on beneath the trees to the benefit of the trees, but the crops from the trees more than make up for the reduction in the forage and cotton crop series.

Concerning this two-story agriculture it is a little-used fact that some plants do not require full sunshine for maximum growth. Mr. H. L. Shantz of the United States Department of Agriculture states that experiments with artificial shading showed that when the light was so decreased as to range from one-half to one-seventh of normal illumination a general increase in growth resulted in potato, cotton, lettuce, and radish. Corn made its best growth in full light.

When we know more about this subject, we may be able to work out a crop rotation that will actually do better when taken from full sunshine to the partial shade made by some kinds of crop-yielding trees, especially in our southeastern area of abundant rain—Cotton Belt and Corn Belt.