Most of the soils were formed under prairie vegetation and are dark colored, high in organic matter and nitrogen, and generally fertile. In the Missouri-Kansas part of the area, however, some forest-formed soils occur. The soils of the South Dakota-Minnesota area were formed from Wisconsin glacial materials and are mostly of loam texture, but in the Missouri Valley hilly area (WP1) and the Nebraska area (WP3) the soils were dominantly formed from silty loess. The latter are well-drained, permeable silt loams except in south-central Nebraska and northwestern Kansas, where some soils are slowly permeable. In the northern part of the Nebraska area, there are several million acres of sandy soils.

Along the Missouri River, which more or less bisects the Nebraska-Iowa hilly area (WP1), the elevation is about a thousand feet above sea level. The adjacent hills are 50 to 100 feet higher. Deep, wide gullies form in the many small drainageways. Sheet erosion is a serious problem on the adjacent steep slopes. Research at the Soil Conservation Experimental Farm near Clarinda, Iowa, has shown the effectiveness of level terraces and contour listing, with legume-grass sod crops and crop residues, in controlling soil and water losses on the deep, permeable sloping soils of this hilly area: Although many farmers have applied these practices, conservation of soil and water remains one of the major problems.

The topography in the other parts of the subregion is mostly level to gently rolling. In the western part of the Nebraska area, which has an elevation of about 3 thousand feet, however, nearly level tabular divides are flanked by steep slopes, which are used for permanent pasture. The South Dakota-Minnesota area is mostly a level to gently rolling plain, although some glacial moraines and hills occur in the northern section.

Moisture conservation is an important matter in the whole subregion, especially in the western low-rainfall section. Stubble-mulch tillage for wheat, listing and minimum tillage methods for corn, and contour cultivation on slopes are used to conserve moisture and control erosion.

Because perennial legumes such as alfalfa lower the reserves of subsoil moisture, sweetclover seeded in the oats and plowed under as green manure has some advantages over alfalfa as a means of supplying nitrogen to the grain crops in the rotation, since it has much less effect on subsoil moisture.

Legumes and manure do not supply enough nitrogen for the grain crops in the rotation, and the use of nitrogen fertilizer has increased greatly since 1945. The need for phosphate fertilizer is considerably less than in the other subregions, but certain soils, such as the calcareous Ida soils of the Nebraska-Iowa hilly area, respond markedly to phosphate fertilizers. Potash fertilizers seldom are needed. Lime generally is not needed except for small amounts on some of the nearly level soils in the southeastern part.

As most of the soils are naturally well drained, artificial drainage is seldom a problem. On parts of the broad bottom lands of the Missouri River and on parts of the tributary streams, however, drainage is troublesome. Such fine-textured, slowly permeable soils as the Luton and Wabash have high water tables in wet seasons, but are difficult to drain.

In this western prairie subregion, where moisture is often limiting, interest has grown in supplemental irrigation. More than 1.5 million acres were irrigated in Nebraska in 1955. Much of it was along the bottom lands of the Platte and Republican Rivers and on the adjacent uplands, where the soils and topography are favorable for irrigation and where water supplies are good. An increasing acreage of alfalfa and corn has been irrigated. To obtain high yields of irrigated corn, the plant population must be high and large amounts of nitrogen fertilizer ordinarily must be used. In other parts of the subregion, topography, soils, and water supply are less favorable, and only a few farmers have tried to irrigate.

Although the cropland is the main agricultural resource of this subregion, about one-third of the land is used partly or wholly for grazing. Because of less favorable climate, increased production from this land has fewer possibilities than from the permanent pastureland of the southern prairie forest subregion. Bluegrass is the common permanent pasture in the eastern part of the subregion, but native grasses are important in the western and northern parts, especially in the rolling glacial sections of South Dakota, where the lower lying wet areas furnish both pasture and hay.

ALTHOUGH THE DIFFERENT PARTS of the Midland feed region vary considerably in soils and climate, the subregions have a general similarity in soil use, primarily because on many farms the production pattern is dominated by corn and the use of legume-grass pastures as the main forage for livestock.

Systems of soil management therefore cannot be identified closely with the different subregions but may vary considerably in any one subregion. In some subregions, however, the ratio of legume and grasses to corn, soybeans, and other intertilled crops in the rotation is much higher than in others.

To meet the twin goals of efficient and sustained production, it is important that the best combination of practices be used. However, the best combination may vary from farm to farm as well as from one area to another. Too, the value of one practice often is determined by the other practices.

For example, experiments in Iowa and other States showed that farmers on the better soils usually cannot expect to get much increase in corn yields from heavy fertilization with only 8 thousand to 9 thousand plants per acre, the plant population used commonly in 1945. In Iowa we found that the use of 80 pounds of nitrogen in fertilizers increased the yield of corn only 14 bushels an acre with a stand of 8 thousand plants to the acre but 28 bushels with 16 thousand plants an acre.

Another example of how several practices complement each other was had on the steep, calcareous Ida soils of the Missouri Valley hilly area. Terracing is an effective way to control erosion and conserve water, but without some meadow crops in the rotation the terraces need to be so close together on these steep soils as to be largely impractical. Moreover, in order to get satisfactory yields of legumes or corn on these phosphorus-deficient soils, large applications of phosphate fertilizers are necessary. Thus, in an experiment at the Western Iowa Experimental Farm at Castana, the average annual yields in a 4-year rotation of corn-oats-alfalfa-alfalfa was 0.6 ton an acre for alfalfa without phosphorus and 3.9 tons with applications of 240 pounds of phosphoric oxide as superphosphate for each rotation. Likewise, the yields of corn averaged 78 and 20 bushels with and without phosphate, respectively. On Ida soils, therefore, any one of the three practices (terracing, legume-grass rotation, and fertilization) without the other two is largely ineffective.

Soil-management systems are not inflexible, however: Under many soil conditions, there are alternative practices or systems of management that the farmer can select.

SOME SIGNIFICANT DEVELOPMENTS in agricultural technology have had an important influence on the soil-management systems of many Midland farms.

Increased mechanization has meant more timely tillage and other operations and greater efficiency of production. It has aided in the development of such improved tillage and erosion-control practices as mulch-residue tillage and terracing.

The use of chemicals to control weeds, insects, and diseases has helped to reduce hazards in crop production and may have an increasingly important effect on tillage practices, soil use, and crop yields. It was estimated that at least 4 million acres of land in corn in the Midwestern States were treated with insecticide or insecticide-fertilizer mixtures to control rootworm, wire-worm, and other insects in 1956.

The greatly increased production and use of fertilizers have had a great impact. In Iowa, Minnesota, Nebraska, and Missouri, the use of fertilizers increased nearly 250 percent between 1945 and 1955, compared to about 50 percent in the entire United States.

The total use of fertilizers in the States of this region increased more than sixfold between 1939 and 1954. The use of nitrogen fertilizers increased more than twentyfold. About 20 percent of the farmers used fertilizer in 1939, and the average amount spent on a farm was about 55 dollars.

Fifteen years later, more than 60 percent of the farmers used fertilizer, and the amount spent averaged about 400 dollars.

The ready availability of large amounts of nitrogen fertilizers means that farmers are less dependent on nitrogen from legumes to supply the nitrogen needs of other crops in the rotation.

MARKED ADVANCES also have been made in the Midland feed region in evaluating the effects of alternative methods of controlling erosion under different conditions of soil and slope.

Values of permissible soil loss have been established for the major soil types, and the effectiveness of various erosion control practices and combination of practices in keeping the losses to these specified limits have been estimated on the basis of all research information available. Thus the estimated soil loss from a Tama silt loam soil on a 6-percent slope of 400 feet length when farmed in a corn-corn-oats-meadow rotation on the contour is estimated to be 8.8 tons an acre a year, which is considerably above the 4-ton maximum allowable limit established for this soil. Terraces reduced the estimated soil loss to 2.0 tons. A shifting to a corn-oats-meadow-meadow rotation without terraces cut the estimated loss to 3.5 tons. Either method is satisfactory. Alternatively, the corn-corn-oats-meadow rotation could be retained if one of the new tillage methods such as residue-mulch tillage is adopted.

Farmers in the region have made great progress in applying the results of scientific research to soil management on their farms since 1945. The potentialities for improvement during the next decade are equally great.

This optimistic outlook is not surprising in view of the scientific findings of recent years from research laboratories and experimental fields.

Chemical soil tests for estimating the fertilizer needs of soil are now available and are being used in testing more than 1 million soil samples annually for farmers in the 12 North Central States. With increasing use of soil tests, even greater efficiency in fertilizer use can be obtained.

From the standpoint of sustained, longtime production, there is also great opportunity of utilizing more fully such specific erosion control practices as contour cultivation, stripcropping, and terracing. On dairy and livestock farms, where good use can be made of forages, there is an excellent opportunity of improving soil use by keeping more of the rolling soils in legumes and grasses. To do that may mean cropping the more level soils on the farm more intensively, a possibility now open to many farmers through improved fertilization and tillage practices.

Many soil-management problems, however, remain to be solved. There is need especially for basic studies to understand more fully the variations in properties and productive capacity of different soils. The Midland farmer needs to know more specifically how various individual practices can supplement or replace one another; what alternative combinations of practices are available for his particular soil and climatic conditions; and what these combinations mean in terms of immediate income and sustained production.