Planting and Cultivating on Stubble-Mulch Land

When small grain is being seeded on land with considerable residue cover, it is desirable that the drill make a clean furrow in which to plant the seed. When this is done, as with a hoe or disk drill, the residue is partly covered, but enough remains on the surface and mixed with the surface soil between the rows to protect the soil against blowing, increase the infiltration capacity, and reduce danger of water erosion.

Seeding alfalfa, clover, or grasses on stubble-mulch land does not require that all the mulch be pushed aside. The shallow seeding makes this impracticable. Drills should be operated so that they will barely cover the seed. It has also been found practical to seed those crops with a seeder attachment on the treader.

Planting row crops through a stubble-mulch requires that the seed be placed in a clean furrow to obtain a better stand and to make future weed control easier. The use of some form of furrow opener on the planter is the best means of doing this. Any germinating weeds and much of the weed seed, as well as the residues, are thrown out of the furrow and between the rows. A treader used ahead of or in tandem with the row-crop planter smooths the ground and facilitates later cultivation.

Much of the residue can be kept on the surface during the early growth of row crops if sweeps, rather than regular shovels, are used for cultivation. A residue cover that affords considerable protection can be maintained on row-crop land usually throughout the period of cultivation, but as the season passes decay renders it less effective. By this time, however, the crop will be large enough to give some protection to the soil.

Tillage that retains residues on the surface can be done at a cost comparable to most other methods of farming, and probably at a lower cost than a system that involves plowing. It usually takes a year or two to get a field into a good subsurface tillage system. After a field is sub-tilled a few times, it tends to become somewhat more uniform on the surface. Any depressions become filled and high spots are leveled. This makes it possible to subtill at more shallow and more uniform depths. It is thus easier to control weeds, since they are most easily killed if undercut at a very shallow depth. It is therefore important that subsurface tillage work be very carefully done. The method requires the right kind of equipment, in proper adjustment. It also requires timeliness of operation. Tillage under proper moisture content and dry weather conditions will be far more effective in eradicating weeds than if the work is done under wetter conditions.

There appears to be no one implement that is more satisfactory than others for subsurface tillage work under all conditions. Best results often require an interchange of implements. The logical tillage program is one that controls weeds and keeps the proper amount of residue on the surface to maintain the capacity of the soil to absorb water and to provide the erosion protection needed. These things can all be done while the soil is given proper tillage for good seedbed preparation.

Application of Results

The fact that stubble-mulching is mechanically feasible and is desirable for erosion control would appear to make it widely adapted. But like all other tillage practices it has limitations that tend to limit the area to which it can be applied. Among those that might be mentioned are greater difficulty under some conditions in weed control, greater incidence of certain insect pests, and reduced formation of nitrates. Under some conditions, however, subsurface tillage is being used as a means of control of certain insects.

The practice of stubble mulching has been given a wider trial and appears to be better adapted to the Great Plains and to the drier parts of the Columbia River Basin than to more humid sections. The factors that reduce yields operate less frequently in those areas, and the need for wind erosion protection is greater. Average yields of small grain resulting from its use are as high as from other methods of tillage. Corn production has not been so widely tested, but results to date indicate that yields tend to be lower under stubble-mulch tillage. Under practical operating conditions, the quantity of residue on the surface should be controlled and so adjusted as to achieve proper weed control and satisfactory operation of tillage and seeding implements.

The effect of stubble-mulch methods on yields of crops under all conditions has not yet been definitely determined. Many comparisons have been made; in some cases yields have been higher and in some lower than with conventional methods. There appears to be a rather definite tendency for stubble mulching to show to advantage under conditions Of low rainfall or during dry years. When rainfall is higher or in more humid regions, subsurface tillage has usually given somewhat lower Yields than plowing. Under such conditions, factors other than moisture may limit yields. The advantage of stubble mulching in saving water would therefore not be important under these wetter conditions. However, under these same wet conditions, the advantage of the mulch in reducing erosion on rolling land may be very evident, and this must be taken into account in the final evaluation of the method.

Much evidence is available to indicate that care needs to be exercised in conducting stubble-mulch farming properly. Slipshod methods will not suffice and the farmer who would be most successful with it must think much of the timeliness of tillage operations. If the work is properly done, there is undoubtedly a great area in this country where yields can be maintained and runoff and soil blowing more effectively controlled than where land is tilled by methods that leave the surface bare a considerable part of the time.

The value of surface residue for increasing intake of water and for erosion protection is generally recognized. Continued efforts should be made to improve field methods and the mechanical equipment needed to effect the degree of erosion control required. Efforts should also be made to increase the area to which stubble-mulch tillage may be adapted, in order to obtain its advantages in soil and moisture conservation over a wider territory.

THE AUTHORS

F. L. Duley, a soil conservationist in the Division of Research, Soil Conservation Service, is in charge of Soil Conservation Service research in Nebraska. In 1923, with M. F. Miller, he published one of the first reports on soil-erosion measurements. He was one of the first group of regional directors of Soil Conservation Service when it was started in 1933. He has published numerous bulletins and journal articles on soil conservation, soil fertility, and soil management. Dr. Duley holds degrees from the University of Missouri and the University of Wisconsin.

O. R. Mathews, an agronomist in the Division of Soils, Fertilizers, and Irrigation of the Bureau of Plant Industry, Soils, and Agricultural Engineering, has been engaged in experimental work in tillage and crop rotation in the Great Plains for more than 30 years. He is the author of many bulletins on crop production, livestock pasturing and feeding, and soil moisture accumulation and use under dry-land conditions. In 1936, with A. L. Hallsted, he published a report on the relation between the depth to which the soil was wet at seeding and yields of winter wheat. The findings reported have been widely used as a planting guide by individual farmers, and as a guide to recommendations by State and Federal agencies. Mr. Mathews holds two degrees from South Dakota State College.