Principles

the yearbook of agriculture 1957 THE UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.

THE UNITED STATES GOVERNMENT PRINTING OFFICE

We Seek; We Learn

Charles E. Kellogg.

Two hundred generations of men and women have given us what is in our minds about soils and soil fertility--the arts and skills and the organized body of knowledge that we now call science.

What is in our hearts they also have given us the lore, traditions, and love for the land as the wellspring of our national life.

Men in ancient times used many practices that we use manuring, liming, and crop rotations with legumes.

In the Odyssey, Homer told how Odysseus the far-wanderer was recognized at his homecoming first by his old dog "lying on a heap of dung with which the thralls were wont to manure the land."

The Romans had several good manuals for farmers, prepared by keen observers who sifted out the best from the experience they saw around them. Columella's Husbandry, written about A.D. 60, was a handbook for 15 generations. Some of his suggestions were good, even in the light of modern knowledge. He discussed amounts of material to be used, timing of operations, and application of combinations of practices to various kinds of soil.

Most of the actual knowledge farmers used during the long period from the fall of Rome to the French Revolution and for some time afterward was the home knowledge of farm people, passed on by father and mother to son and daughter. Their practices were highly traditional and slow to change. Yields of crops were low.

After Rome fell, the people of Europe were disorganized and lived in a dark age of disease, famine, and war for more than a thousand years.

But the Arabian culture flourished in the Near East, northern Africa, and southern Spain. Farming there was reasonably good, especially under irrigation. In the 12th century, for example, Ibn-al-Awan, a Moorish scholar, prepared an excellent handbook of agriculture. The experience he recorded and explained became significant to us much later through the Spanish influence brought into early settlements in the southwestern part of the United States.

Greater stability of governments came with the close of the Thirty Years War in 1648. Populations began to increase. Since yields remained low in much of western Europe, the growing populations began to press hard against the food supply. The new stability of governments stimulated intellectual activity, and out of it the first principles and skills of modern science were born. For the first time, economic problems were recognized and studied.

These new forces and ideas seemed to be unrelated for many years. In 1798 Thomas R. Malthus wrote his Essay on Population, in which he developed the idea that populations increase faster than the food supply and that it was probable that some people would die of starvation. He had no way of foreseeing the tremendous effects that technology would have on crop yields in Europe or on the development of vast new lands overseas.

Attempts were made to rationalize farming and to improve soil management. Near the beginning of the 18th century, Jethro Tull, an Englishman, invented the grain drill and the cultivator, which he called a "horse hoe." Weeds had choked grain fields; now crops could be sown in rows and cultivated.

Tull demonstrated that cultivation could be helpful, but he gave a wrong reason that cultivation helped plants take in small particles of earth, especially clay. It is simply one example of how a practice, which is good on some kinds of soil, may be established through observation and advocated for all kinds of soil for the wrong reasons. The effect of Tull's insistence on much cultivation lasted a long time. Until recently farmers have over-cultivated their soils beyond the need to incorporate organic matter and fertilizers, to make the soil receptive of rainwater, and to control weeds.

Jethro Tull's practices helped the further development of crop rotations to replace the earlier "two-field" system, in which a year of wheat alternated with a year of fallow.

The Norfolk "four-course" system, developed partly from experience in Holland, had such an advantage over wheat and fallow that it has persisted as a cornerstone of agriculture in the minds of many to this day.

In the original Norfolk system, turnips for cattle feed were grown as an intertilled crop, followed by wheat and 2 years of clover or clover mixed with grass. Sometimes the second year of grass was replaced by another year of wheat or other small grain. Soil fertility was maintained by the clover and manure. Weeds were controlled. The soil was kept in good physical condition by the roots of the meadow crop and by the organic matter returned in the manure. Yields of grain were doubled. Eliminating the fallow meant the soil could be used for crops and pasture all the time.

But here again, results that were so helpful to many of the soils of England were recommended too widely. Arthur Young, an English agriculturist, wrote in 1792 as follows:

"Hence then some courses [rotations] arrange themselves that are applicable, perhaps, to all the soils of the world.

"I, Roots, cabbage, or pulse.

"2, Corn [wheat].

"3, Grasses.

"4, Corn.

"and, 1, Roots [turnips], or cabbage.

"2, Corn.

"3, Grasses.

"4, Pulse, or maize, hemp, or flax.

"5, Corn.

"And in these the chief distinction, relative to soil, will be the number of years in which the grasses are left...."

It took a long time and much research to establish clearly that other systems are better for most kinds of soil that are unlike those of western Europe.

SCIENTISTS meanwhile were trying to find out what made plants grow. They assumed that one "principle" could be found. In the 16th century, Bernard Palissy, potter to French royalty and a man of great affairs who finally died in a dungeon of the Bastille, maintained that manures and plant residues returned to the soil the "salt" that plants removed. He regarded the ash left when plants burned as "a kind of salt" and the "principle" of plant growth. But experimental results were disappointing before chemistry had developed the skills necessary to distinguish among the many kinds of "salt."