Better Pastures Depend on Soil Fertility
THE INCREASED DEMANDS for food under wartime labor shortages on the farm are bringing us face to face with the problem of wisest management of our lands for their direct delivery of milk and meat through animal harvests of their crops. The use of more pasture crops, and the more efficient use of lands already in pasture, suggest themselves as wise means of greater output of food with minimum labor. But many so-called “permanent” pastures go to weeds so extensively that much labor and machinery are demanded in mowing them. In addition their animal-carrying capacity is often so low that their service in terms of food production scarcely warrants their consideration as significant war crop producers when in contrast a few tilled acres in other crops could be so much more effective in animal output.
But since Missouri—as is true of many other States—is already a grain-importing State, the arable acres should go for grain production. Consequently the grass and forage needs must be met by attention to those acreages already devoted to herbage crops. Shifting these acres out of pasture and into row crops is not good agricultural policy as the first World War told us. That their animal output per acre can be improved; that their labor, costs in terms of the fight against weeds can be reduced; and that their season of grazing service can be extended—all by means of supplying some soil fertility—has not been widely recognized. The permanent timothy plots and the timothy crops in rotation on Sanborn Field bear testimony that these are possibilities that can be realized.
Soil Treatments Push Up Grass and Hay Yields
Lands in pasture have seldom been given much help toward greater production by means of soil treatments such as limestone, phosphate, or other fertilizers. Pastures have been a kind of stepchild on the list of different crop uses of fields of the farm. They have usually been disregarded when manure was to be hauled out. Manure has been considered more valuable on lands going to grain crops. Data from Sanborn Field at Columbia, however, testify that manure used on the permanent timothy plots has given the highest returns per acre and per ton of manure applied on this old experimental field when it was put on the grass crop.
Where timothy has been the continuous crop now for more than 50 years, the annual application of six tons of manure has netted a ton and a quarter of hay as the increase. Where three tons of manure have been used on timothy following clover in a six-year rotation this barnyard fertilizer has also given a ton and a quarter of hay as its return. Where this light application of manure was combined with phosphate, this application of soil fertility has given just about a ton and a half of extra timothy hay as the return on the investment put into the soil for a common pasture crop. When pastures are the areas left over after acreages for intensified tillage are listed, and they can be put into intensified production of food via milk and meat through soil treatment, there is every reason to give thought to fertilizing the pastures now when fertilizer use pays so well and when food is needed so badly.
More Fertile Pastures Save Labor of Weed Mowing
Much has been said about the need to mow pastures as a means of eliminating the weeds. It has been contended that cutting the weeds is necessary in order to keep them from going to seed and spreading their infestation. We have given a little thought to the fact that the incidence of weeds in a pasture is evidence of declining soil fertility, which if pushed up to a higher level by lime and other fertilizers, would grow grasses so well that weeds would find no place.
This fact is again well illustrated by the plots on Sanborn Field. On the continuous timothy plots where manure has been applied annually there are no weeds. It needs mowing only in making hay. It is a fine mat of densely-growing timothy plants. Where no fertility is returned and the timothy is left to maintain its pseudo-permanence through efforts wholly its own, there has been a gradually increasing incidence of weeds. After a period of about six to eight years in sod the land must be plowed and reseeded to this crop. This has been the behavior of this grass plot during 55 years of its history. It testifies that as a permanent grass plot there is permanence only in the adjoining plot where manure is returned as soil treatment. There is no permanence when left without attention to its fertility. When ample fertility grows a good grass crop there are no weeds to mow. Where the fertility is not returned weeds require mowing.
During this past year the timothy plot without manure demonstrated nicely how permanent pastures like this one, neglected as to fertilizer treatments, shift over to become fields of broom sedge (Andropogon virginicus). It was eight years ago when these timothy plots were last plowed and reseeded as a means of maintaining them under the more nearly comparable crop conditions required in careful experimental studies. Weeds of various kinds have taken their prominence in the succession of them on the untreated plot. It was not until fall, however, after the weed collection had been cut for hay during the summer, that this plot became a complete stand of broom sedge. It was as late as November that this weed crop blossomed and set its seed crop. Broom sedge demonstrates its final and complete possession now as a perennial weed crop on this soil where many other weed crops have had their short stay and then passed out as the exhaustion of the available fertility starved them out. Here now mowing might seem necessary, but of what profit or service would it be?
Different Degrees of Soil Fertility Invite Different Weed Infestations
That the infestation by broom sedge during this year was confined so thoroughly to this untreated permanent timothy plot, while all the other plots on the field were not taken by this weed suggests that the level of soil fertility is a factor in making the land susceptible to a particular weed infestation. Different weed crops represent their own different chemical compositions as the studies by A. W. Klemme demonstrate. As such, each weed crop demands delivery of soil fertility in different chemical combinations of kind and amount. Broom sedge as a crop suggests that it can find enough fertility in the soil after a series of other weeds have taken their share and then found themselves starved out. As the last to date in the succession here it made 3,700 pounds of vegetation per acre even after the summer cutting for hay. Apparently as a perennial crop with its root stock sending up new shoots each year, it could get a foothold only in this plot remaining long unplowed. It apparently cannot establish itself in the other plots of the field, all of which are in rotations and do not have periods of absence of plowing longer than three years.
In the six-year rotation where the timothy was the crop in 1943, the untreated plot was also devoid of timothy. The treated plots had a good timothy crop. In place of the broom sedge, however, the weed that had taken the untreated plot completely as early as August was not broom sedge. It was tickle grass (Aristida). As an annual this weed crop made its entrance on this cultivated soil that had been reduced in its fertility through continued crop removal and with no soil treatments as fertility return. On the uncultivated continuous timothy plot just across the roadway, however, the weed infestation was a perennial crop of broom sedge. Differences in the rotation and in the amount of plowing brought different weed crops to demonstrate difference in these infestations.
More Soil Fertility Means Immunity to Weeds
Exhaustion of the soil fertility to make the land susceptible to weed infestation is clearly pointed out by these two cases when all the other plots on the field were immune. There is little danger that the seeds from these weed crops will infest the rest of the field, when surely the seeds that infested these susceptible plots last year fell likewise on all the other plots but failed to grow up as weeds. Mowing of these weedy plots now in order to eliminate the danger of infesting the rest of the field is thus unnecessary, when it has already been demonstrated that the other plots grow other crops so completely that these weeds find no place in the keen competition for the nutrients of the soil.
Higher levels of soil fertility, brought on and maintained by the use of manure and fertilizer, are thus demonstrating that they give larger yields of the desirable crops to which the fields are planted. In addition, the soil treatment eliminates the weeds and saves the trouble and expense of mowing them. It controls the weeds, not by fighting them, but by better nourishment of the paying crops that eliminate them. In terms of labor saved by eliminating weeds, soil treatments are good economy, particularly when mowing machines are rationed and costly, and when summer labor is scarce.
More Soil Fertility on Pastures Lengthens the Grazing Season
Dairy farmers, in particular, have often reported the pronounced economies that could be effected by extending the fall-grazing season by only one month. This extension is considered so significant because it eliminates one month of wholly-barn feeding. Little has been said for the possibilities in the much better feeding value of the green feed that is rich in hidden values. One extra month on such a feed may be extremely significant as a reducer of the time period on dry feeds when disease incidence is high, and the reproductive load is approaching its peak.
Soil treatments on Sanborn Field demonstrated again this past year that increased soil fertility prolongs the growing period of the grass crop and thus extends the grazing season. Timothy plots given manure, given less manure and limestone, and given manure, limestone and super-phosphate were still green in late November. Extended growth of the crop by giving it some soil fertility by which it can keep on growing suggests that we have possibly been labeling the crops as “short-seasoned” when in reality they have been merely starved by poor soils. A small amount of limestone, phosphate or other fertilizer to keep a crop growing longer appears as a simple method of extending the grazing season.
More Soil Fertility Means More Nutritious Feed, Better Animal Health and More Meat per Acre
In shifting to pasture crops as they are to provide a larger share of farm production there is the serious danger that we shall let increased woodiness and lower feeding value of the forages creep in unnoticed. Grain crops record the declining soil fertility by lowered yields of grain per acre. Grains are more nearly of constant chemical composition. Hence if the soil is too poor to provide generously the nutrients going into the grain, there simply is less grain. Forages measured as tons per acre do not reflect differences in soil fertility so accurately. Plants on soil too poor to make seeds still make tons of forage. But such forage that wouldn’t take seed can’t deliver for animal sustenance many of the nourishments that go from the forage to the seed in its formation and serve in the nutrition of animals.
As the fertility of the soil declines, there come into the pasture those crops which the animals refuse to eat and which are commonly call weeds. Animal choice testifies to the plant’s chemical composition. Broom sedge is not taken by cattle. Sedge still makes tons per acre. So does tickle grass. But the disregard of them by the animals testifies that it is not the tonnage that serves in making meat. Mowing the weeds to eliminate them brings no change in the fertility within the soil.
As the fertility declines there is a change in composition within the same crop. As the soil delivers less of nitrogen, phosphorus, calcium and other plant nutrients then the crop is made more of carbon, hydrogen, and oxygen, or of air and water that make for woodiness. It is not so much an increase in woodiness as a decrease in what the plant manufactures inside of its woody structure. It is these different substances synthesized within the plants that are particularly nutritious. It is these that can be lacking even when tonnage harvest seem ample. This is the phase that may be the deception in our going to more forage crops unless we provide extra soil fertility.
Meat production is first a growth performance and later a fattening process. Growth is a matter of getting from the plants about a dozen chemical elements that the plant must first get from the soil. Fattening depends on the delivery of carbon, hydrogen and oxygen, coming from the air and water. But fattening cannot occur unless soil-given nutrients first make the growth of body frame. For growth and reproduction of the animals, soil treatments are of distinct value. The effects of lime and phosphate on the soil as they reach through the crops to the animals have been demonstrated recently. Lespedeza hay grown in 1941 on soil given phosphate only was 30 per cent more efficient, and that given both lime and phosphate was 67 per cent more efficient in promoting lamb gains than lespedeza hay grown without these fertility applications. Potency of males as breeders is also connected with the fertility of the soil. All of these effects add up to make pastures more efficient, and not hazardous, if we will see that the plants are fed with fertilizers before we can expect the pastures to feed the livestock.
Pastures like all other fields cannot be disregarded with reference to manures and other fertilizers and yet cropped continually without loss in their yielding power. The soil is dynamic. It is delivering the elements of fertility that serve in plant growth and likewise in animal growth. This delivery is not perpetual. It is dwindling and with its decreased offerings have come changes in the kinds and qualities of the pasture plants. The incidence of weeds and the refusal of the animals to eat them have been the dumb beasts’ plea for our attention to the soils. They have been calling for some help toward their better growth and more efficient reproduction by means of limestone, phosphate and other fertilizers as soil treatments. War necessities, priorities, labor shortages, and other impositions are bringing us to realize that grasses are no escape from diligent farming that is based on fertile soils.
Not only growth improvement results when the hays are grown on fertilized soils but also better animal physiology as shown by better bones.
Pasture Farming Can be a Paying Kind of Farming
Farming has higher earning power on the investment as the yields per acre go up. These go up as the soil has more fertility from which they are synthesized. Limestone and other fertilizers should be added to the pasture soils just as to soils in other crops. Such treatments will improve the tonnage of grass crops per acre with no increased cost of harvest by the animals that do so as pay for the privilege with more animal gain.
Soil treatments lessen the costs of attention to weeds by eliminating them, they extend the grazing season well into the fall; and they shift the composition of the herbage toward improvement of animal health, nutrition, and more animal gain per acre. Pasture grasses can be pushed up most effectively and also animal harvest therefrom increased with the soil treatments. As a war help, pastures are an unusual opportunity for more food production. But for its realization we must look to the fertility of the soil.
Animal choice testifies to the differences in chemical composition of the crop when hogging down of corn takes first the areas given soil treatments. Farm of Cliff Long, Warrensburg, Missouri. (Photo by County Agent Virgil Burke.)
