A second serious problem in this section is erosion. Water erosion is most severe on bare, sloping lands. When adequate steps are taken to conserve all possible moisture for crop use, water erosion rarely should be a serious problem because the methods used to conserve moisture help control erosion.

The occurrence of wind erosion usually is associated with consecutive drought years, although other factors may influence the amount of soil drifting that will occur.

Nearly every farmer in the dryland section knows the principles of the control of wind erosion.

Several States in the region have laws that permit county commissioners to order emergency tillage conducted on farmland that is menacing neighboring lands by its erosiveness. The cost of this tillage is added to the taxes of the farm.

Conditions beyond a farmer's control sometimes may reduce vegetative cover enough that wind erosion may occur during the windy spring months. On the medium- to fine-textured soils, it may be possible to roughen the surface of the soil so that its erosiveness is greatly reduced. This is necessary in emergencies even in the growing crop. Sandier soils need plant material, either living or dead, to reduce their erosiveness to manageable proportions. That is one reason why sorghums, whose residues may be left undisturbed on the land until after the spring winds are past, are better adapted to sandier soils than small grains.

The stubble-mulch tillage has been highly recommended as a means of reducing water and wind erosion. This practice, particularly during the fallowing operation, has much to commend it. The residues are not completely destroyed by the tillage and remain mixed with the surface soil to help resist soil movement. Yet the residues are not sufficiently bulky after the fallow period to interfere with seeding even if the ordinary disk-type grain drill is used.

In the northern and central areas of this subregion, the prevailing direction of the winds that cause erosion is south-north. Planting crops in strips(east-west) across this prevailing direction will help to reduce erosion by cutting down the width of bare or fallowed fields. The alternate strips, to be effective, must provide protection against erosion in all seasons, but particularly in early spring. The destructive winds are not predominantly in any one direction in southern areas. Here stripcropping has much less to recommend it.

Areas of sandy soils are extensive in southwestern Kansas, the Panhandles of Oklahoma and Texas, southeastern Colorado, and northeastern New Mexico. Many have a low content of clay in the surface layers (2 to 5 percent) and are particularly erosive when they are cultivated. Deep plowing of certain of these soils will help control wind erosion. Where the erosive surface layers are underlain by subsoils with 12 to 25 percent of clay at depths that can be reached by large plows, deep plowing can be used successfully. If fine material cannot be brought to the surface by plowing, no improvement in wind erosion control is obtained.

Deep plowing is not a cure-all on sandy lands. Continued sifting by wind can cause deep-plowed land to lose its increased clay content and become as erosive as ever. The deep-plowed land can trap flying sand particles from neighboring farms. That will dilute the fine surface texture prepared by plowing. Deep-plowed land should be handled with a cropping system that will reduce to a minimum the loss of fine material from the soil. Deep plowing should be undertaken on a community basis.

Although low fertility is not usually considered a problem in most dryland areas, some crops on specific soils may respond to fertilization. In tests in most States in the region, only the sandy soils seemed to respond consistently enough to warrant the use of fertilizer. Since crop growth and fertilizer response in this section are tied so closely to situations of moisture and temperature, recommendations as to fertilization have to take them into consideration. No areas in this subregion are known where response is obtained to applications of potash. Some areas are deficient in phosphorus, but most soils seem to have enough phosphate.

Nitrogen seems to be the element most likely to limit production. Sufficient nitrogen usually is present in dry years for the growth of the crop the moisture can produce. In fact, more than ample nitrogen supplies seem to be produced in dry seasons, because symptoms of nitrogen deficiency are rarely noticed in a wet year immediately following a dry year. Perhaps it takes several consecutive humid years to demonstrate nitrogen deficiency symptoms on noneroded dryland soils.

Crops on noneroded, productive, hard-land soils have not responded to applications of manure. Crops on sandy lands may respond to manure applications. Usually manure neither increases nor decreases crop growth. In several instances, however, lower yields have followed applications of manure. Applications of manure on poorly drained or eroded soils or on saline or alkali spots have improved soil properties and plant growth in many instances.

As wheat and sorghums and possibly corn in the northern areas are the cultivated crops best adapted to the dry-land soils of this subregion, there appears to be little chance for crop rotations. In fact, many farmers who grow both wheat and sorghum on their farms as a regular practice tend to produce the wheat continuously, or alternately with fallow, on specific fields and to produce the sorghums on entirely different fields. A number of farmers alternate wheat and sorghums on individual fields, but the sorghums are planted only if the soils are too dry for wheat seeding in the fall or if the wheat crop fails to become established over winter. On the other hand, some farmers follow a sequence on their land of fallow, wheat, sorghum. Others use a cropping sequence of fallow, wheat, fallow, sorghum.