In the story of "My Grandfather's Earthworm Farm" George Sheffield is quoted as saying, in regard to the care of trees, "Never disturb the soil under a tree. The earthworm is the best plow for taking care of a tree." The wisdom of this remark is appreciated fully only when a study is made of the subject of orcharding. When we go to nature where primeval forests have stood for centuries, we find the ground riddled to great depth by earthworm burrows. Earthworms like to work in the shade, among the fine roots of trees, finding sustenance in the organic debris and bacterial life of the soil, in the dead bacteria as well as the products of bacterial life. Aside from vegetation, there is a vast world of unseen bacterial life in the soil, amounting in aggregate weight in the case of fertile agricultural lands to much more than all animal life which crawls, creeps, walks, runs, and flies on and above the surface of the ground. Because we do not see this microscopic universe, we may not visualize or sense its extent.
The multiplication of bacteria is so rapid that, starting with a single cell, under favorable conditions, the numbers will reach astronomical figures within a few hours, with a bulk and weight of such magnitude that the human mind cannot grasp the total. The number of bacteria in an ounce of fertile topsoil is variously estimated as from eighteen million to twenty-four billion. When we consider that bacteria appear as dots under the microscope when magnified one thousand times, the results of such multiplication become still harder to grasp. If we were to magnify a man to one thousand times his size, he would appear more than one mile tall and a quarter-mile broad. On this point we shall quote from Bacteria in Relation to Soil Fertility, by Dr. Joseph E. Greaves (M.S., Ph.D., Professor of Bacteriology and Physiological Chemistry, Utah Agricultural College):
A bacterial generation is taken as the time required for a mature cell to divide and the resulting daughter cells to reach maturity. This process may be completed in half an hourat times even more rapidly. Under less favorable circumstances it may be much longer. It has been estimated that if bacterial multiplication went unchecked the descendents of one cell would in two days number 281,500,000,000, and that in three days the descendents of this single cell would weigh 148,356,000 pounds. It has been further estimated by an eminent biologist that if proper conditions could be maintained for their life activity, in less than five days they would make a mass which would completely fill as much space as is occupied by all the oceans on the earth's surface, if the water had an average depth of one mile.
Lest some reader becomes alarmed about bacteria, let us state that they are self-limiting, the same as other life-forms, being strictly limited by the amount of food available in their environment. Also, the by-products of their own life-processes accumulate rapidly and, as it were, they are soon stewing in their own juice to their own destruction. Incidentally, it is doubtful that, in the absence of the bacterial life of the soil, the higher forms of animal life could exist. Like the earthworm, bacteria are the unseen but ceaseless transformers of the end-products of life back to the soil in the eternal cyclefrom earth, through life, back to earth.
The above may at first appear as a digression from the subject of orcharding. However, in considering the nutrition of trees through the aid of earthworms, it is important to understand fully the source of nutrition for the worms as well as for the trees. There is much more sustenance in the soil than may be derived from the gross forms of vegetation in and above the earth. So, in considering the life of a tree and its nutrition, it is well to examine the elements which enter into its growth and maintenance.
We stand in awed amazement as we contemplate a Sequoia gigantea, towering nearly three hundred feet into the air, bearing within its bulk trainloads of material, carrying concealed within its growth-rings its recorded age record of perhaps three to five thousand years. Where did it come from, how did it grow, from what hidden source does its mighty heart draw its inconceivable strength? No man has carried small bags of chemical fertilizer in a foolish attempt to help nourish this tree into its giant size. No man-made plow has disturbed the surface of the earth at its base. Yet here it stands, with a life-span reaching toward a geological age. We are reminded of the scriptural injunction, "Consider the lilies, how they grow," and might well paraphrase the line to read, "Consider the trees, how they grow!"
When we come to orcharding with the aid of earthworms, we should not be too much concerned about fertilizers, or worry at all about cultivation. The thing to do is to offer a little friendly cooperation with nature, stand back, and watch the tree grow.
While the same principles apply to orcharding in general, our studies of the earthworm in orcharding have been confined for the most part to citrus orcharding, by reason of the fact that we live in Southern California where citrus fruit is the main orcharding industry. Some time ago we visited the great orange-growing section around Riverside, California, the particular end of our journey being "Hanford Loam," a grove which the owner, Mr. Frank Hinckley, has operated by the non-cultivation method for a period of more than twenty years. Mr. Hinckley is a hard-headed, successful orange grower and business man who has made money growing oranges. He has been growing oranges all his life and his experience covers a period of more than forty years. He is well educated, well informed, methodical, and practical; and, as he has kept careful records for many years, he has his data and knows what he is talking about. The ten-acre tract comprising Hanford Loam is one of the outstanding groves of the state. We were amazed at the size and luxuriance of the trees. Many of the leaves were of such unusual size as to be almost unbelievable when compared with the foliage of the average orange tree.
Mr. Hinckley's own story of his experience in developing this grove conveys the facts in a most forceful manner. After our visit to his place, we wrote him a letter, requesting a report for our records. Under date of October 17, 1939, we received the following letter.
Dear Doctor Barrett:
I have your letter of October 10th and will try to give some information that will be of value in your research.
I might say that my experience with the earthworms is more on the practical side than on the experimental. On one of my ten-acre groves, Hanford Loam, I discontinued all cultivation about eighteen years ago. At that time the twenty-eight-yearold trees appeared to have reached their limit as to size and production, about three hundred boxes per acre per year.
The first year after changing my cultural method to one of non-cultivation, I noticed a great difference in water penetration. Plow sole was eliminated, the trees started growing, and they have continued to do so ever since, until now they are large, fine trees, and my production average for the last fifteen years has been about 630 boxes per acre per year.
Soon after I quit all cultivation, I noticed that the earthworms were doing a wonderful job of tilling the soil; they eliminated all plow sole, leaving the ground porous and mellow. I also perceived that they were feeding on the leaves that had accumulated in the furrows and around under the trees. Raking the leaves out from under the trees and placing them beneath the drip of the trees encouraged the worms to work that portion of the soil most, as it kept more moist. Under such ideal conditions, the earthworms rapidly increased until now they are able to work every foot of soil in my grovein fact, I might say the soil is continually in motion. As the trees have a heavy foliage of large leaves, the leaf-drop seems to furnish ample food for the worms.
I have used a soluble commercial fertilizer, calcium nitrate or sulphate of ammonia, for the past twenty years, with the exception of one year when I used cottonseed meal. Until six years ago I averaged about 3¼ pounds of actual nitrogen per tree per year, but the last six years I have averaged 1 1/3 pounds of actual nitrogen per tree per year. There has been no organic matter added to this grove since the fall of 1919. The quality of the fruit has been above the average; also the sizes have been in the desirable brackets. In my opinion, there is no doubt that the earthworms add fertility to the soil besides conditioning it.
I also have a twenty-acre grove in sandy soil, which I took care of in the mechanical way for fourteen years, and I saw very few worms in all that time. For the past fourteen years, however, I have applied my non-cultivation method, and the worms are increasing every year. They started at the lower end of the furrows, where the soil is heaviest; and as the soil changes from the accumulation of leaves around the trees, the worms are able to live and increase.
These groves are kept clean of weeds by hoeing; the furrows have become shallow and wide from hoeing and raking the leaves. The water can thus cover a larger area of the surface, making as much soil as possible available for the worms to use during the dry season, without extra expense.
I also have a lot of sixty-five orange trees at home, which I purchased a year ago. This soil is a heavy red soil and very subject to plow sole. I am well pleased with the way the worms have multiplied and eliminated the plow sole under my method within the year; and they will no doubt continue to better the soil and aid the trees.
In regard to the amount of water used, I find that since the worms have opened up the soil water penetrates more freely. I can irrigate in a much shorter time and with a larger volume of water per furrow. Under this method of non-cultivation, I use a little less water, but the trees are able to use more of that which is applied.
Our Deputy Farm Adviser is making a graph, consisting of the sizes, grades, and amount of boxes covering the past twenty years. When I receive these data, I will be glad to send them to you if you so desire. Thank you for your interest in my work.
Very truly, (signed) Frank Hinckley
At the date of this writing, January of 1944, it is of interest to point out that Mr. Hinckley had eliminated the plow from his orcharding operations more than twenty years before the appearance of Edward H. Faulkner's book, Plowman's Folly, currently on its way to becoming a best seller. Since receiving the above report from Mr. Hinckley, we have visited his place a number of times and a good many interesting details have been brought out, with many things not covered in his letter. One of the most astonishing statements was made by him in answer to our question, "How much money do you have invested in machinery?" Mr. Hinckley replied: "I have thirty acres in oranges in Hanford Loam and another grove near here. I believe my total investment in machinery is less than ten dollars, consisting of hoes and rakes. A near neighbor, with thirty-two acres of oranges, has over four thousand dollars' worth of machinery and hires an expert to operate it. I call in a Mexican boy every other month and we go over my groves with hoe and rake to eliminate the few weeds which come from seeds that are blown in by the wind."
Mr. Hinckley stated that after the initial change from the old cultural methods, his labor costs were less. By use of the hoe promptly to eliminate weeds, never allowing them to go to seed, the orchard was soon practically free from weeds. No tractors or machines are required in the non-cultivation method; therefore the trees do not need to be trimmed high. In Mr. Hinckley's orchard the trees have been allowed to develop until the limbs practically touch the ground, maintaining a dense shade over the entire surface and an unfavorable environment for weeds. Also the shade conserves surface moisture and this favors the development of a large earthworm population.
In the case of Mr. Hinckley, there was no special propagation of earthworms. He simply created a favorable environment for the development of the native earthworm population, discontinued plowing and breaking up their breeding grounds, provided cover for the worms in the form of leaf-drop raked underneath the drip of the tree, and the worms began to multiply. After a few years this grove has become one vast earthworm culture bed. At the time this chapter is written, Mr. Hinckley's orchard is over fifty years old and is in greater production than ever before, whereas at the time the new method was started the grove was twenty-eight years old and was not showing a profit. In fact, it was going back.
In orcharding with the aid of earthworms, a small, highly productive, long-lived orchard, with top quality fruit, lower labor costs, less fertilizer costs, and the practical elimination of culls, can be made to take the place of a much larger acreage under the generally accepted cultural methods. Through earthworm culture, young groves can be brought to profitable production in a much shorter period of time than by the old methods; and the life of a grove, with earthworms instead of plows, extends far beyond the life of a grove where the earthworms are constantly retarded in their development by frequent ploughing. And where heavy use of chemical fertilizers is the practice, the earthworm population may entirely disappear, and, in addition, the highly important bacterial life of the soil be inhibited.
The quickest method for developing earthworms in orchards is to establish generous colonies of "domesticated earthworms" under each tree, with organic fertilization similar to that used on "My Grandfather's Earthworm Farm." By this method the proliferation of earthworms is accelerated many times beyond anything found in nature. Within a few months results may be obtained which would otherwise require years. Methods for intensive propagation of domesticated earthworms for all horticultural purposes will be taken up in later chapters.
Since becoming acquainted with Mr. Hinckley and his methods and results through "earthworm tillage," we have had reports from a number of other orchardists. We will mention one small tract in particular, a five-acre grove near Costa Mesa, California. This grove is rated very highly by the citrus-growing people. It is handled by methods similar to Mr. Hinckley's grove; that is, methods which we have called "earthworm tillage." For the year 1945 the owner of this grove stated that he received a gross amount of $7,500 for his orange crop from these five acres. Examination shows that the entire tract is really a great earthworm culture bed. From a few such reports investigated, we are led to conclude that the earthworm doubtless deserves credit for many of the outstanding results which have been observed in other successful orchards.
While we have discussed the earthworm in citrus orcharding, the same principles apply to other types of orcharding, as well as to general farming and production of food crops. What we wish to emphasize, regardless of vegetation under consideration, is that with earthworms and the other allied forces of nature, utilized properly, we obtain a soil with a maximum of plant nutrients in available form. From such soil, experience has shown that maximum production results are obtained, both in quantity and quality.