Southeastern Uplands

R. W. Pearson and L. E. Ensminger.

The Southeastern Uplands is one of the oldest major agricultural sections of the country. It produces nearly all of our flue-cured tobacco, about one-third of our cotton, and more than half of our peanuts.

The region has a long growing season and mild winters. The number of frost-free days ranges from 200 in the northern part to 260 in the extreme south. The average winter temperature is about 45 F. throughout the area. The average annual rainfall is 50 to 60 inches in all of the area, except in parts of Oklahoma and Texas, where it is about 35 inches a year.

The distribution of rainfall and the low water-holding capacity of the soils are factors in the crop production potential. Between 5o and 70 percent of the total annual rainfall comes during the cool season, October to March. The frequent shortage of rainfall in the growing season and the restricted water-holding capacity of all but a few soils mean that moisture is deficient for crop growth during some periods in almost every year.

The soils are of the Red-Yellow Podzolic group. They were derived from a variety of parent materials. They developed generally under forest vegetation and in a climate that favored a high degree of weathering and leaching of bases from the profile and prevented the accumulation of sizable amounts of organic matter. Thus the soils are predominantly acid in reaction and low in organic matter and plant nutrients. The conservation of soil and water is a major problem in a large part of the region. Much of the land is hilly. Many of the soils are naturally erosive. Rains of high intensity occur often in spring and summer.

The problem of loss of soil and water is intensified in the Piedmont, Brown Loam, and the Clay Hill sections of the Coastal Plain. In years gone by, when the agriculture of the Southeast was based strictly on row crops, farmers there often were forced to abandon fields because of severe gullying. The situation has changed. Pulpwood has become a major source of income on rough and eroded areas that would have been useless a generation ago. The expanding livestock production has created a need for more pasture and forage, which have restored many an eroded cultivated field to useful production.

A larger acreage of abandoned land in the Southeast is being restored to useful production each year than is being lost from production because of erosion. The hazard of erosion still exists, however. The continued application of sound principles of land use and soil management will be necessary if the maximum use is to be made of potentially productive soils.

Acreage controls, labor shortages, and other economic factors have built up a tremendous pressure for raising acre yields, especially of cash crops. That and several dry years have focused attention on supplemental irrigation as a way to intensify production of cash crops, provide insurance against crop failures, and even out seasonal irregularities in forage crops and pastures.

Irrigation has a place in intensive crop and livestock production in the Southeast. In dairy farming, for example, great possibilities exist for marked increases in production of temporary grazing crops and for shifting the growing period right into the critically dry fall season.

Crops such as millet and Sudangrass are responsive to nitrogen and moisture. They grow fast and yield well. The use of supplemental irrigation to establish seedings early in the fall and to insure rapid growth can raise yields tremendously in autumn. At Thorsby, Ala., in 1955, for example, Starr millet and alfalfa drilled in alternate rows in late August, irrigated, and heavily fertilized, produced more than 4 tons of high-quality forage in September and October and went into the winter with a vigorous stand of alfalfa.

Supplemental irrigation will undoubtedly be an important factor in the production of such cash crops as cotton, vegetables, fruit, tobacco, and flower bulbs in some localities. It probably will not affect the average level of production of the major crops in the region as a whole in the immediate future, however, because such problems as water supply, cost of installation of irrigation systems, and the high level of management it requires for successful crop production will sharply limit its application.

But the best job of management with respect to fertilization, liming, control of insects, and other practices is essential before supplemental irrigation has a chance of becoming economically sound. Crop yields in the Southeast on the average have been limited by inadequate levels of available plant nutrients, and irrigation can only produce increased yields after these other limiting factors are removed. Irrigation without proper attention to other required practices could actually depress yields. For example, added water usually leads to more luxuriant foliage of cotton plants, and that favors the development of bollworms and weevils.

Another limiting factor is water supply for irrigation. The flow of the many streams in the region often is low during the dry season. The competition of several farmers for water for irrigation from such streams often dries them up.

Wells are not dependable as an economic source of irrigation water in much of the region. Farm ponds can help as an emergency supply, but ordinary ponds cannot provide enough water for full-scale irrigation of field crops. The importance of supplemental irrigation may continue to increase, but locally it will be determined largely by the availability of water.

Rates of fertilizer application on the better managed farms in the Southeast have increased since 1935. This increased rate, the relatively higher proportions of soluble constituents in fertilizers, and the low buffer capacity of many soils lead to another problem that of the proper placement of fertilizer at planting to avoid seedling damage because of salt injury. Stand and yields, particularly of oilseed crops in much of the Southeast, are lowered when fertilizer is applied directly under the seed instead of at one side.

The question of the most effective placement of lime and starter fertilizer for permanent pasture has received considerable attention, but we do not have the complete answer. Bandseeding grass and legumes for pasture in combination with drilled fertilizer sometimes is superior to broadcast seeding and fertilizer placement, particularly when conditions are adverse to establishment of seedlings. The deep placement of lime and phosphate does not seem to be better than surface application for the maintenance of pasture sod. Of course, basic applications of lime and phosphate in preparation for establishing pasture should be incorporated in the plow layer. Further study of the problem will be necessary, however, before a dependable conclusion can be reached as to the value of building up the nutrient and base status of the deeper soil layers.

The soils of the Southeast and their management requirements differ considerably. Therefore the region has been subdivided into eight physiographic areas, within which the soils and their management problems are more nearly alike.

THE COASTAL PLAIN forms a belt of upland soils 100 to 300 miles wide along the Atlantic and gulf coasts. It includes about 115 million acres. It extends from south-central Texas to north-central North Carolina. It is the heart of the old Cotton Belt.

Considerable differences in rainfall within the geographic range of the Coastal Plain influence strongly the use and potentialities of the soils. Most of the region east of the Mississippi River gets 50 to 60 inches of rain, but precipitation drops off rapidly west of the river to only 31 inches in Guadalupe County in Texas.

The soils were developed from marine sands and clays and are predominantly sandy in their surface horizons. The topography is gently rolling to hilly. Both surface and internal drainage are generally good. Among the extensive series are the Norfolk, Ruston, Orangeburg, Red Bay, and Magnolia soils. The upland soils have light gray to red sandy surfaces, 5 to 10 inches deep, underlain by yellow-red, friable, sandy clay subsoils. The C horizon, beginning usually at 2 to 3 feet, is mottled gray to red, unconsolidated sands and clays.