An official website of the United States government.
USDA Historical Publications on Soil Conversation and Productivity
[T]he main work to be done for soil conservation in this country is that of teaching the farmer how to utilize the resources at his command. The methods to be pursued are, in the main, understood by leading agriculturists and progressive farmers all over the country, but they are not understood by the great majority of farmers. The latter must be taught by precept and example. It will take time to bring about the necessary change.
Spillman, W.J. (1910). Soil Conservation.
U. S. Department of Agriculture. Farmers' Bulletin, Number 406, p. 15.
The U.S. Department of Agriculture has worked hard to teach farmers both by "precept and example" best practices for increasing agricultural production and soil health, especially through publications. Here is a sample of publications on soil productivity and conservation written around the same time as Carver's bulletins.
(Click any image in this exhibit to get more information, including access to full text)
"We may sum up the matter briefly thus: To build up and maintain fertility in the soil, feed a large part of the crops and return the manure to the land. If manure is not available, plow under crops grown for the purpose. Plow deep (but do not subsoil). Grow leguminous crops for the nitrogen they add to the soil.
Commercial fertilizers and lime may be important means of improving the soil, but the fertilizer requirements of different soils and different crops in different seasons are so little understood that we are not yet in a position to make positive recommendations that are of general application."
"This bulletin is an account of the progress made in three years in changing a run-down cotton plantation into a profitable stock and hay farm. The results obtained from the use of cowpeas and other leguminous crops in restoring the fertility of the land have exceeded the expectations of those in charge of the work. Not only have the crops yielded greater returns each year, but all the grain and hay necessary to feed 14 brood mares, 1 jack, 2 driving horses, 1 saddle horse, a varying number of mule colts, a cow and calf, and from 50 to 75 hogs has been raised and a considerable surplus of grain and hay sold each year.
However, it is only fair to state that all of the credit for this increased production is not due to the legumes alone, because at the start an entirely new system of farming was put into operation; modern implements took the place of the old ones, the land was plowed deeper, better drainage established, improved seed introduced, and better methods of cultivation practiced, each doubtless contributing something to the general improvement.
GENERAL CONDITIONS IN 1905, 1906, AND 1907.
The farm referred to in this bulletin consists of about 375 acres of slightly rolling land at the foot of Crowleys Ridge, in Phillips County, Ark. The soil is a reddish silt loam, with occasional patches of sandy loam. The lower levels of the farm are very poorly drained, and in consequence the crops on these portions have suffered greatly during seasons of excessive rainfall."
"A careful study of the data which have been presented appears to justify two conclusions.
First. That the productivity of the newer agricultural soils of the United States and of the older agricultural soils of Europe, taken as a whole and for a nation, are not declining, as is popularly supposed. Individual farms deteriorate and soils wear out as they have always done, but as a whole it seems probable that we are producing more crops per acre than formerly. This is undoubtedly due to many factors; to better and more intelligent cultivation, more and better systems of rotation of crops, and, in later years, to intelligent use of fertilizers — three methods of control in the hands of every individual farmer. In addition, we must recognize the increase in farm animals and stock, the improvement in seed by selection and breeding, and the increasing density in population, which is forcing attention to more intensive methods.
Second. That so far as our information goes there is apparently no significant difference at the present time between the composition of the older agricultural soils of Europe and the newer agricultural soils of the United States with respect to potash, phosphoric acid, lime, and magnesia."
"How to restore and maintain the productivity of the soil is the most important phase of the conservation problem. We are no longer a new nation. We have deluded ourselves with the idea that we have unbounded resources in land, in forests, in mineral wealth. We have been prodigal in the utilization of these, resources. We must now pay the penalty of this prodigality. In many of our older communities soil fertility has been reduced below the point of profitable production. Nation-wide effort at the present time, through federal and state agency, is directed toward the restoration of fertility in these localities. On the prairies of the West fertility is beginning to wane. In order that our heritage in the prairie country may not follow the descent of the East and the South, it is necessary that intelligent and vigorous effort be made to farm correctly. We must cease abusing the soil. The renting of land on short leases for the purpose of growing grain for market is one of the surest means of reducing the productive power of the soil. The domestic animal, with well-managed pastures and rational systems of crop rotation, is preeminently adapted to the development of permanent systems of profitable farming. Landowners must realize this and must take steps to improve renting methods by stocking farms with a full complement of domestic animals, where the renter is not able to do this for himself, and by giving longer leases, whereby the renter may reap the reward of intelligent management."
"SUMMARY
(1) Commercial fertilizers are expensive. Accurate information is needed for their economic use.
(2) With a good rotation, deep and thorough tillage, and the use of green manures, legumes, and winter cover crops, the quantity of commercial fertilizers required for a given crop yield can be considerably reduced.
(3) The character of the soil has a marked influence on the quantity and kind of fertilizer it is necessary to use in a good system of farming.
(4) In farm practice there is a gradual increase in the quantity of all the fertilizer constituents required to produce like yields as the proportion of sand in the surface and subsoil increases. The increase is greatest in the quantity of potash necessary, followed by phosphoric acid, and then by nitrogen.
(5) A study of farm practice shows that the best farmers, those referred to in this bulletin as belonging to Class A, obtain yields of 1 to 2 bales of cotton, 40 to 75 bushels of corn, and 40 to 75 bushels of oats on soils where farmers of Class B get but one-half to 1 bale of cotton, 15 to 40 bushels of corn, and 15 to 40 bushels of oats, duo to the fact that the best farmers have a better understanding of the use of fertilizers and employ better farm methods.
(G) One of the most common grades of fertilizer on the market in the South Atlantic States at present contains 8 per cent of phosphoric acid, 3 per cent of ammonia, and 3 per cent of potash. This grade of fertilizer is of primary value only for cotton on red clay soil under fairly good methods of rotation. This fertilizer formula needs to be greatly modified for crops on sandy, sandy loam, and gray loam soils, and for all crops other than cotton on red clay soil.
(7) Detailed suggestions aro contained in this bulletin on the best method of fertilizing and the most profitable kinds of fertilizer constituents to apply on soils of different character to cotton, corn, oats, wheat, and cowpeas."
"Throughout the prairie belts of central Alabama and northwestern and central Mississippi occur extensive areas of a dark-colored upland calcareous clay soil which, in addition to being admirably suited to the production of cotton, corn, and grass, is highly adapted to alfalfa.
This upland type of "black prairie land" has been classified by the Bureau of Soils as Houston clay. It is distinctly different from any other soil in the southeastern part of the United States, except an alluvial type derived from it, the Trinity clay, which is also a dark-colored soil rich in lime. These soils are also extensively developed in the prairie or "black waxy land" regions of Texas, where they were first mapped and named. Owing to the fact, however, that the extent of the Houston and Trinity soils in Texas has not yet been so completely determined as in Alabama and Mississippi, and for the further reason that different climatic conditions prevail over these lands as developed in the State of Texas, this bulletin, for the sake of direct and brief treatment, will take up only the Alabama-Mississippi region, throughout which both soil and climate are strikingly uniform. While the Houston clay is the dominant upland prairie type, there are occasional small areas of a closely related soil, the Houston chalk, and some patches also of another related type, the Houston loam."
"In the limestone and mountain districts south of the Ohio River there is much land that has been run down by continual cropping without rotation. In some places run-down land is left to grow up in weeds, wild grasses, and brush, a practice known as "resting" the land.
Where this sort of farm management is followed farm manure is largely wasted, little or no attention is paid to green-manure crops or other means of putting humus into the soil, and crop yields are very low. However, progressive farmers throughout the region who have built up run-down lands are now getting heavy yields.
In the following pages are described some of the methods by which these farmers get results by making good use of farm manure and crop refuse, using legumes and grasses in regular rotations, and applying lime and commercial fertilizers."
"Two methods have been employed in evaluating the effectiveness of rotation in crop production, and in determining the additive effects of rotation and the use of fertilizers when these two farm practices are conjoined. Although in one method the evaluations are based on the increases over the yields obtained on check plots in continuous culture and in rotation, and in the second method, on the increases over the maintenance yield; or the average yield obtained at the beginning of the experiments, yet the general results as regards the value of rotation in relation to soil productivity all point in the same direction.
The evaluation of crop rotation as calculated from the maintenance yield seems to be the more logical and scientific method, especially from the point of view of maintaining and increasing the producing power of the soil. However, in determining the values for rotation and the use of fertilizer when one practice is combined with the other, or in determining the relative value of R. the first method referred to above has been found to be very useful.
Taking all the results into consideration, as based on the average results of the published data of the long-time fertility experiments herein considered, the following important facts as regards the value of crop rotation have been brought out:
(1) Rotation of crops is practically 75 per cent as effective as the use of fertilizer in effecting increases in crop yields — being nearly 90 per cent as effective as the use of fertilizer when the results on wheat, corn, and oats, only, are considered.
(2) As based on the, average yields at the beginning of the experiments involving fully comparable yields, rotation has been shown to be 91.5 per cent as effective as the use of fertilizer in maintaining the producing power of the soil.
(3) In increasing soil productivity, the effects of rotation alone may equal or exceed the effects of the use of fertilizer without rotation.
(4) The effects of rotation and the use of fertilizer apparently are not the same, as is shown by the fact that their conjoint effects on crop yields are additive — being more than fully additive in most of the cases considered.
(5) In permanent crop production, high productivity levels are possible only when rotation and the use of fertilizer are conjoined."
"A study of the long-continued soil-fertility experiments of this country and of England, made by the Department of Agriculture. 1 has brought out the following important facts about crop rotation in its relation to soil productivity, as determined by the soil conditions under which these experiments are conducted:
(1) In general, crop rotation has been found to be practically 95 per cent as effective as farm manure and complete commercial fertilizers in maintaining the yields of wheat, corn, and oats, and about 90 per cent as effective as these fertilizers in increasing the yields of these three major crops.
(2) The beneficial effects of crop rotation do not impair the benefits derived from the use of fertilizers; so that when these two farm practices are combined the one practice adds to the benefits of the other.
(3] When compared with the effectiveness of manure and commercial fertilizers, the relative value of crop rotation is practically 2O per cent higher on soils sufficiently supplied with lime than on soils that are acid.
(4) On soils long under cultivation the highest yields are possible only when the use of manure or commercial fertilizers and rotation of crops are conjoined or practiced together."
"This bulletin describes farming practices that conserve soil and how such practices may he applied to farms in a large part of the South. Its scope is limited to that part of the Cotton Belt extending west from the Georgia Alabama line to central Texas and southern Oklahoma. Its subject matter is based largely on the soil conservation practices employed by farmers who live within the various project areas of the Soil Conservation Service in this section of the cotton country. Erosion control practices for cotton farms to the east are described in Farmers' Bulletin 1767, Soil Defense in the Piedmont."
"Maintenance of soil productivity is to a large extent bound up with the maintenance of organic matter, which serves to decrease the danger from erosion. Legumes take a prominent place in maintaining soil productivity. Winter legumes are most commonly depended on in the South; red clover and sweetclover in the North. Turning these crops under, wholly or in part, maintains the organic matter at a satisfactory level and adds nitrogen to the soil.
Summer legumes may and do also serve the same purpose. Cow- peas and soybeans harvested for hay do not add materially to the organic matter in soils. At best they serve as a mechanical summer cover. If turned under entirely they serve the same as crotalaria to add to the soil organic matter. Practical experience has shown that the annual lespedezas even when cut for hay will increase the following crop of cotton or corn. Data on the quantities of organic matter left in the soil by such a crop are wanting, but even when annual lespedezas are cut for hay a considerable quantity of organic material is left, and the resulting increase in crop yields is commonly impressive."
"Some of the Nation's richest land, and some of its poorest, lies in the 13 cotton - and - tobacco States: 28 percent of the country's area, a region rich in natural resources, advantages of climate, population, and potentialities.
Industry is growing in the South, but the region still is predominantly agricultural. In addition to cotton, tobacco, and corn, this region produces a large proportion of the Nation's fresh vegetables and fruits for the great markets of Washington, Philadelphia, New York, Boston, Chicago, and other northern cities and towns.
These States produce all these things for the North, but not so much for themselves. And eventually, large parts of this vast region may not be able to produce so much for the northern markets, unless more positive action is undertaken to restore and conserve the soil resources of these 13 vital States.
The cotton-and-tobacco States include more than a fourth of all the land in the United States, and a fourth of the total area of these States now is being used as cropland — 124,500,000 acres given over to growing cotton, tobacco, corn, vegetables, peaches, apples, nuts, and subtropical fruits for the Nation. The agriculture of these 13 Southern States is a vast business."
"The wealth of this Nation is rooted in the soil. Thirty million people earn their living directly from farms and ranches. The remaining 100 million Americans depend upon the soil for most of their food, much of their clothing, and many other necessities.
Today the soil of this Nation is being wasted away. Erosion is steadily washing good soil out of the fields and pastures, into the streams, down the rivers, and to the sea."