Soil Mining or Soil Building

Soil Mining or Soil Building?

by C.J. Chapman
Extension Service of the College of Agriculture,
The University of Wisconsin, Madison, February 1938

Those of us intensely interested in all aspects of better farming, including organic and biodynamic practices and systems, are frequently fascinated by the history of agricultural propaganda. Now, please, keep in mind that not all propaganda by definition is bad stuff. It is most definitely a case of view point and cultural belief married to the drumbeat of a cause. But it is interesting to this old farmer that we can look way back before WWII and find government literature which ‘couched’ farming language in a telling and deliberate fashion, wrapped as it is in certain basic truths, and all aimed at a questionable conclusion. That conclusion being that there was (and is) no way of maintaining, let alone growing, soil fertility without chemical inputs. From this premise and political viewpoint grew, as reaction, the amazing work of people like Sir Albert Howard, the founders of the present organic farming movement.

What follows is a well-written treatise on early Wisconsin soil concerns. We do not offer it as purely applicable to present day concerns about whether to use chemical fertilizer or not. We offer it as a piece of regional soil science history as well as a piece of early USDA propaganda. If we are to continue to grow as better farmers we need to keep this information where we can get to it, for in our understanding and response there will be new possibilities. LRM

“The history of every nation is eventually written in the way in which it cares for its soil.” –Franklin D. Roosevelt

Are Wisconsin farms being mined of their fertility? Yes, it certainly is true that Wisconsin farms are losing fertility at an alarming rate. The average Wisconsin dairy farm is losing phosphorus and potash at a rate equivalent to 1 ton of 20% superphosphate and at least 1 ton of 50% muriate of potash each year. We have piled up in the past 50 years of farming a total loss of phosphorus and potassium equivalent to at least 50 tons of 20% superphosphate and 50 tons of muriate of potash.

We have labored under the false impression that where all crops grown on the farm were fed to livestock and the manure returned to the land, we were keeping up the fertility of our soils, and keeping the plant food of our farms in circulation.

But what evidence have we to show that we are actually losing fertility at these rapid rates? The best evidence, of course, is the fact that our soils are not as productive as they used to be. Clover seedings have failed in recent years; there is more lodging of our grains. Corn does not mature as it did in the early days. Yields of corn and grain have not increased. All this, in spite of improved and higher yielding varieties of corn and grain and better tillage machinery.


It is true that stable manure is a good fertilizer. Every effort should be made to save this valuable source of plant food and get it back on the land. The liquid portion is especially rich in nitrogen and potash. However, the supply of manure on the average farm is limited. There is not enough to go around. Even where every forkful of manure is saved and returned to the land, it is apparent that the level of fertility is not being maintained.


We estimate that in Wisconsin we are producing about 30,000,000 tons of manure each year. Valued at $3 a ton, this source of plant food on the basis of present prices for commercial fertilizers is worth nearly $100,000,000, yet authorities estimate that fully one-third of the plant-food constituents of manure is lost. In spite of the most careful handling of manure, there are unavoidable losses of plant food.

We are then losing yearly better than $30,000,000 worth of plant food from our soils, even where most all crops grown on our farms are fed to livestock and the manure returned to the land. Wisconsin farmers are buying less than $1,500,000 worth of commercial fertilizers each year. 1937, about 42,000 tons of commercial fertilizers were used on Wisconsin farms, which at $35 per ton amounts to about $1,500,000.


We know that milk is rich in phosphorus. Eight thousand pounds of milk contain the equivalent of 100 pounds of 20% superphosphate. A good cow will produce 8,000 pounds of milk a year; so, we are losing the equivalent of a 100-pound sack of 20% superphosphate for each cow in our herds. If a farmer is milking 20 cows, he is losing the equivalent of 1 ton of 20% superphosphate in the sale of milk each year.

Every 1,000 pounds of livestock sold from the farm carry the equivalent of nearly 100 pounds of 16% superphosphate. We are selling calves, hogs, poultry, and poultry products; and 2 or 3 head of cattle are sold every year. Every 40 bushels of barley or 30 bushels of wheat sold from the farm carry with them phosphorus equivalent to 100 pounds of 16% superphosphate.

It is true we have offset part of our losses in the purchase of bran, oil meal, and other concentrates which are rich in phosphorus. But the amount of phosphorus added to our farms through the purchase of feed will offset not more than one-fourth of the total loss incurred in the sale of milk, livestock products, and cash crops.

We can readily see then that phosphorus is being lost from our farms at an alarming rate, but it is not so easy to figure the actual loss of potash, since milk and livestock products contain relatively small amounts of it. It’s true that where we sell cash crops, that is, grain, hay, potatoes, tobacco, sugar beets, canning peas, cabbage, and other truck, we do lose large amounts of potash. In fact, if we figure the pounds of plant food actually sold and lost from the farm, we note that there is a tremendous loss of available potash from our farms.


But even on the dairy farm, where all crops grown are fed to livestock we are safe in saying that at least 30% of the potash removed from our cultivated fields never gets back to the land. In fact some authorities say that on many farms in this state where manure is carelessly handled, upwards of 40% of this potash is lost in the feeding transaction and subsequent handling of the manure.

Many farmers may feel too that they have plenty of total potassium in their soil because soil chemists have told them they have from 30,000 to 40,000 pounds of elemental potassium per acre.

But it’s necessary to remember that only a small percentage of this total amount is becoming available each year. Cyril G. Hopkins of Illinois used to say that less than ½ of 1 per cent of our total potassium was becoming available each year on the better soils. (Of course, Dr. Hopkins was never really much worried about an eventual potash shortage.) But now if we figure that we are losing 30 to 40% of the available potash each year, and bear in mind that this has been going on for the past 75 years, is it any wonder that some of even our best soil types are responding to potash treatment?

Take the case of William Renk & Sons, owners of four farms on one of our best soil types in this state (Carrington silt loam). The Renks have limed every acre of tillable land of their farms. They manure liberally. They have grown legumes on an extensive scale. They have been outstanding livestock farmers — great sheep feeders. They have purchased thousands of tons of feed concentrates, and yet, surprising as it may seem, their soils are responding to the use of fertilizers rich in potash.


The Renks purchased a large combination drill in 1937 and fertilized all of their barley — about 71 acres. They used an 0-20-10 at the rate of 200 pounds per acre. They left a few check strips here and there on some of the fields. We harvested comparable areas in order to find out the increase in yield. The year of 1937 was good for grain, and the average yield on the fertilized barley (0-20-10 treatment) was 55 bushels per acre, as compared to 38 ½ bushels per acre on the check strips. Although rust did hit the fields and reduce the yields somewhat, yet rust hurt the unfertilized much more than it did the fertilized, due to difference in stage of maturity when the rust hit. Here’s a 16 ½ bushel increase in yield on what has been considered land in good fertility.

The more general use of fertilizers applied at the time of seeding down to alfalfa or hay and pasture mixtures is being recommended. In the past, Wisconsin farmers have been using considerable fertilizer on cash crops such as potatoes, sugar beets, cabbage, and canning peas. Many farmers have applied small amounts of fertilizer with an attachment on the corn planter, and have observed good results. We recommend these practices. The practice of hill dropping a small amount with an attachment on the corn planter has done much to improve the quality, increase the yield, and advance the maturity of our corn crops in Wisconsin.

But good as it is this small local application of fertilizer to corn is not building up the fertility of our farms as a whole. More and more farmers are finding that the drilling or broadcasting of fertilizer at the time of seeding is proving a profitable investment. Not only will the fertilizer increase the yields of small grains, but the residual benefits will carry over to the second and third year. Increases of a half ton in the yield of alfalfa or clover are common. Furthermore, the use of fertilizer at the time of seeding may make the difference between a good catch of seeding and failure.


Our soils are losing organic matter rapidly and becoming more and more acid. They have lost their humus through the growing of soil-depleting crops, such as corn, small grains, and cash crops. Unless something is done right away to stop these losses, unless we shift more of our land from soil-depleting to soil-conserving crops, unless we resort to the use of more fertilizers and lime in maintaining a balanced state of fertility, the future prosperity of farmers in Wisconsin is in real jeopardy.

By liming we are laying the foundation for more productive soils. Lime not only corrects acidity but also supplies available calcium to our lime-loving crops. It is also helpful in making other plant foods available, especially phosphorus. Liming acid soils stimulates bacterial life, thereby helping to make the plant food contained in organic matter available to growing crops. The liming of our soils will improve their texture; will produce a more friable, granular soil.


During the past four years something better than 2,500,000 tons of lime have been produced and applied to Wisconsin farms under our state and federal lime production program, but this amount is sufficient to cover not more than a tenth of the acid soils in the state. It is estimated that less than a fifth of the farm lands in Wisconsin have been limed. There are still better then 6,000,000 acres of acid, lime-deficient soils in the state. Even when we have covered every acre of acid land on our farms, it will be found desirable to start right in again and re-lime most of our soils.

While it is true that liming is a basic step in a soil-building program, yet by reason of the stimulating effect that lime has on most acid soils, we are really pumping the soils harder and harder. In fact, the liberal use of lime will eventually make the need for phosphate and potash greater. And right here let’s observe that the liming of our soils, the growing of more alfalfa (a heavy potash feeder) will reduce the amount of purchased feeds and thus further increase the need for more commercial plant foods. This situation already exists. The acreage of alfalfa in Wisconsin has doubled during the past four years. We harvested better than 1,000,000 acres of this great crop in 1936 and again in 1937. And this all means heavier demands on the mineral resources of our soils.


The federal government is now engaged in a gigantic program of soil conservation. A program for the control of wind and water erosion has been set up in every part of the United States. Large scale erosion control demonstration projects are being established. Hundreds of engineers and agriculturists have been hired to supervise this work. CCC boys are doing much of the physical work in remodeling farms and watersheds, building terraces and dams, and planting trees for shelter-belt protection as a means of controlling wind and water erosion.

Our soil conservation and crop control program is just another approach to conservation. It is true farmers are being paid to shift acreage from soil-depleting to soil-conserving crops, being paid to seed down their land to pasture and hay crops, and being paid to use lime and fertilizers in a constructive soil-building program. Really these better soil-management practices are justifiable on the basis of added income and the long-time productiveness of their soils.


The results of fertilizer demonstrations conducted during the past five years on a wide range of soils throughout southern and central Wisconsin prove conclusively that it does pay. The summary below shows the average yields of grain (oats and barley) from those plot demonstrations where we had a direct comparison of 20% superphosphate against a check plot and one in which 10% of potash was added to the superphosphate.

Soil Mining or Soil Building

In the above demonstrations, the average application of fertilizer amounted to about 200 pounds per acre. The cost of 200 pounds of 20% superphosphate at present is about $2.50. At an average value of 55 cents a bushel for oats and barley the increase for the superphosphate treatment is $4.01, leaving a net profit of $1.51 over and above the cost of phosphate. Two hundred pounds of the phosphate-potash fertilizer (0-20-10) at present prices is about $4.00. The value of 10.5 bushels of grain at 55 cents is $5.77, leaving a profit of $1.77 over and above its cost.

Of course, it is hardly fair to charge the entire cost of the fertilizer against the grain crop for we know that the residual carry-over on seedings of alfalfa, clover and timothy will show benefits for two or three years following.

The figures show the average benefit the first year following the application of fertilizer on the hay crops. Average increases for 25 of the same farms mentioned before are shown.

Soil Mining or Soil Building

There has been an average increase of 580 pounds for 20% superphosphate. Where potash was added to the phosphate, an increase of 1004 pounds resulted. With hay valued at $12 per ton, the increased yield from phosphate treatment would be $3.48. In the case of the phosphate-potash treatment, a value of $6.02 was obtained. This really is pure gain, since the fertilizer more than paid for itself the year before in increased yields of grain.

Editors note: Please remember that the values presented above were those of 1938. Grain prices are highly unstable as we enter the first stages of synthetic-fuels crop speculation but you can bet $.55 oats are a thing of the distant past. As for the current value of manure and compost many of us cannot agree. LRM