Raising and Culturing Earthworms
Excerpts from Thomas J. Barrett's Harnessing the Earthworm
(Bruce Humphries: Boston, 1947; copyright unrenewed.)
Part 1: Humus
All flesh is one, including man, in its demand for nutrition to survive, but man alone demands infinitely more than mere nutrition. Through his conquest over the forces of nature, man has adapted himself to all conditions and environments and lives wherever there is air to breatheon the surface of the earth, in the sky, under the earth, on the surface of the waters, under the sea. His frozen footprints are preserved for future ages in the regions of the north pole and the trail of the tractor pushes steadily into the unexplored continent locked in everlasting winter around the south pole. His air-conditioning creates a cool spot for luxurious comfort astride the equator, and he squats nonchalantly within the rim of boiling volcanic cauldrons and takes the temperature of mother earth and diagnoses her fevers and convulsions.
To serve the demands of the ubiquitous adaptability of man, to speed up production of necessities and luxuries for his use, to create new and useful things to satisfy his growing needs and desires, are some of the practical ends of scientific research. Because of his adaptability and conquest over the forces of nature, man has cut loose from his mother's apron stringsthe earthand we find the populations of civilization throughout the world, in large part, marooned on the islands of villages, towns, and cities, segregated and separated from the landvast aggregations of restless, discontented children, playing with the machines and toys which science and invention have provided and uniting in a mighty cry and cosmic bawl for food.
Let the flow of food to the cities stop for a single day, and its cessation is headline news. Let the flow stop for two days, and it becomes tragedy of major proportions. Let it stop for a week, and panic seizes the people as starvation takes hold.
In checking over the annual requisition of the human family for food and supplies, we are staggered by such items as these: Rush the harvest of 4,954,000,000 bushels of wheat, and prepare 366,000,000 acres of land for replanting. Husk 4,942,000,000 bushels of corn and prepare 209,100,000 acres of land for replanting. Round up 182,365,000 head of cattle for beef and butter, milk and shoes. Ship 38,159,000 bales of cotton to the factories, with 3,692,000,000 pounds of wool, that we may be clothed and kept warm. And in the United States, where we are peculiarly peanut-conscious, we find a small item of 1,291,655,000 pounds of peanuts; also a citrus fruit item of 67,067,000 boxes.
In the annual Year Book of the United States Department of Agricultural Statistics, several hundred pages of fine print are required to tabulate and report on the annual food crops of the United States and the world. We have mentioned a few of the major items that are included in the annual demands of the human family for food and clothing. We have briefly indicated the size of the order to call attention to the fact that the basic source of all these materials is humus, the immediately usable supply of which is concentrated in the eighteen-inch surface crust of the earth and in the more favored and very limited areas of the globe. And humus is not found in inexhaustible mines below the surface of the earthin the better soils it diminishes almost to the vanishing point at a depth of thirty-six inches. It is there potentially, just as food is potentially present in the crude elements of the earth.
Humus is the end product of plant and animal life and must be created for current use from day to day and season to season. In the cycle of nature, the available material must be used over and over; it is nature's method to convert, transmute, disintegrate, rebuild. All vegetation, all life, contributes its quota. From the single-celled yeast plant floating in the wind to the majestic, towering nearly three hundred feet into the air, from microbe to manall have been couched in the bedding ground of humus. And all eventually find their way to the common burial placethe compost heap of natureto be converted into humus and serve in the unbroken cycle of nature.
For the most part, the populations of the earth dwell along seashores and lakes, along rivers in the valleys, and in the low-lying foothills and great plains of the torrid and temperate zones, where the great humus factories of nature are located. Because water runs down hill, this is so. From the dust-laden winds of the desert, from star dust and the dust of disintegrating comets and planets, from the weathered face of the rocks and hills and mountains, nature gathers her materials, and from the mother-waters of the sea she creates the rains and washes the atmosphere. And in the end, from the millions of square miles of high ground, the waters find their way into all the settling basins of the earth to deposit the elements of life in the humus factories of nature.
In her vast humus factories, nature uses many processesslow combustion, chemical disintegration, bacterial decomposition, fermentation, heat, light, darkness, wind and rain, frost and sunand earthworms; all these unite, finally to form that thin surface layer of dark earth in which life is rooted. As volumes have been written and are constantly being written on these many processes through which nature attains her ends, we will not burden these pages with detailed discussion on this subject. Suffice it to say that many of the processes are slow, requiring years, centuries, agesyes, aeons of time; for the first thin blanket of parent material of humus which was spread over the surface of the earth in preparation for the birth of life was the deposit of star dust, disintegrating planets and comets, and the invisible particles brought to the earth by the rays of the sun and other whirling bodies which are scattered, like wind-blown particles of dust, throughout the infinite reaches of space.
Taking the earth as we find it, the creation of humus from dead vegetation and animal life is usually a process measured in terms of weeks and months, or a number of years, with one notable exception: When a requisition is put in for a few million tons of humus, to be prepared over night for emergency plant food for tomorrow, nature marshals her vast earthworm army to a feast; and, behold, the miracle is accomplishedthe order is filled and the crying children of the plant world are fedthe night-soil of earthworms, castings, is deposited on and near the surface of the earth, ready for immediate usefor earthworms excrete humus. No waiting, no worry, no confusionjust the ordinary, routine, daily transaction of business in the humus factories of nature.
Earthworms are the shock-troops of nature for the quick production of humus while she is waiting upon her slower processes. Climaxing her millions of years of experimentation, she created in miniature a perfect humus mill, easily adapted to the use of man. In the body of the earthworm we find a complete, high-speed humus factory, combining all the processesboth mechanical and chemicalfor turning out the finished product, topsoil, properly conditioned for best root growth and containing in rich proportion and in water-soluble form all the elements required of the earth for plant nutrition.
For detailed information and classification of earthworms in general, we refer the reader to the voluminous writings on the subject of "Earthworms" which may be found in the Zoology section in the reference department of most public libraries. We are interested in the function and work of earthworms rather than in a study of the animal from a zoological standpoint.
While many hundreds of species, including marine worms, are comprised in the order Phylum annelida, our interest centers in the Oligochaeta and that portion known to science as the "small-bristled ringed worm." They are distributed all over the planet, including the islands of the sea, from the tropics to extreme northern and southern latitudes, except in the arctic and sub-arctic regions and glacial and sub-glacial regions where the ground may be frozen to great depths over long periods of time.
In size, earthworms range all the way from small worms of almost microscopic dimensions to giant annelids measuring from three feet to eleven feet long. The larger members of the family are found in certain parts of South America, Africa, Ceylon and Australia. The largest of the giant worms, Megascolides Australis, is found in Australia, where authentic measurements of worms up to eleven feet in length have been made.
In the torrid and temperate zones more than one thousand species of earthworms (some authorities say more than 1800) live and procreate. Whatever the name, size, or habitat, earthworms have one important characteristic in commonthey swallow the earth with all that it contains, and in the process of digestion and elimination excrete practically neutral humustopsoil rich in water-soluble nutrients for plant life.
Narrowing the field down still more to the particular purpose of this inquiry, we are interested in the group of earthworms common to the United States and known under various popular and colloquial names, such as "angleworms," "dewworms," "night crawlers," "night lions," "fishworms," "rainworms," etc. The last name, "regenwurm," is very generally used in the extensive German literature on the subject.
For practical purposes and for reasons given later, we shall eliminate from consideration all worms except the rainworm (Lumbricus terrestris), illustrated in Fig. 1, and the brandling, or stinking earthworm (Helodrilus foetidus), illustrated in Fig. 2. The brandling is commonly known as the manure worm.
The rainworm is a native of the fields and forest, lawns, gardens, orchards, meadows, and pastures. It commonly lives in the upper eighteen inches of soil, devouring ceaselessly, day and night, dead roots, leaves, and all dead organic materials, digesting and utilizing them to serve its bodily needs and finally ejecting humus in the form of castingsthe manure of earthworms. But the rainworm is not entirely concerned with the thin surface layer of the earth, though that surface layer is its main feeding and breeding ground. It quite generally burrows to a depth of five or six feet, and earthworm burrows have even been found at depths of from ten to fourteen feet. From these deep burrows into the subsoil the earthworm returns to the surface, bringing new mineral parent material for topsoil and depositing it in the form of castings. These castings from the deep layers of the earth surface are not just sterile, mineralized earth. In the journey through the alimentary canal of the worm they have undergone chemical changes, taken on new material, been ground and thoroughly mixed, and when they are deposited on and in the immediate surface of the earth this new material has become humus-laden topsoil, ready for immediate use by growing vegetation.
In the colder climates, the rainworm burrows deep below the frost line during the winter season, lying dormant while the ground is frozen, but coming to the surface as soon as the spring thaw has warmed the earth. However, the rainworm is very hardy, remains active in quite low temperatures, and has even been observed in slushy snow.
Under particularly favorable conditions, the rainworm often attains a length of twelve inches or more. A more usual length for a fully mature rainworm is five or six inches, with an average length of eight inches.
The brandling, or manure worm (Helodrilus foetidus), is a small, very active, very prolific worm, characterized by a disagreeable odor when crushed or injured. Its favorite habitat is manure piles and compost heaps, hence its name "manure worm." Contrary to general belief, however, the manure worm readily adapts itself to the same environments favored by the rainworm. The brandling gorges voraciously on manure and decaying vegetation, digesting, deodorizing and converting all such material into rich, clean humus, with an odor similar to fresh-turned meadow earth. The castings of the manure worm, like those of the rainworm and the many other species of earthworms, contain a very high percentage of water-soluble plant nutrients.
The manure worm is not a deep-burrowing worm like its relative the rainworm, but prefers to work in the surface areas under rotting vegetation, manure, and other decaying materials. However, after becoming adapted to the soil, it is soon a good burrower and will take care of itself in almost all climates. The manure worm is found widely distributed throughout the United States and in Europe, both in the southern as well as in the colder latitudes. In size, it may attain a length of six inches or more, but in measuring a large number of mature manure worms we determined an average length of about four inches. In intensive propagation and use of earthworms, size is important and the smaller varieties can be utilized with better results than can the larger worms. This point will be emphasized later.
Finally, when we come to the subject of the intensive propagation and use of earthworms in soil-building for agriculture, horticulture, orcharding, nursery, and home gardening, we shall discuss somewhat at length what we have termed "domesticated earthworms." The term "domesticated" is applied to earthworms which have been developed through selective breeding and feeding methods in a controlled environment especially created to favor intensive propagation, as opposed to native earthworms which are found in most fertile, well-watered soils.
From this brief discussion of the earthworm family, we pass to a consideration of the feeding habits and digestive functions of earthworms, which make them possibly the most valuable animals on earth.
We are indebted to the ancient Greek philosopher, Aristotle, for the apt phrase which literally describes the function of these master-builders of topsoil. He called earthworms "intestines of the earth." W. L. Powers, Soil Scientist, Oregon Agricultural Experiment Station, termed the earthworm a "colloid mill." This, too, is a very good descriptive name to indicate the activity of earthworms in soil-building. They literally serve as colloid mills to produce the intimate chemical and mechanical homogenized mixture of fine organic and inorganic matter which forms their castings. In the mixing which takes place in the alimentary canal of the earthworm, the ingested materials undergo chemical changes, deodorization and neutralization, so that the resultant castings (manure) are a practically neutral humus, rich in water-soluble plant food, immediately available for plant nutrition.
As flexible as silk, as strong as steelthese similes may well describe the body of an earthworm. Known as one of the strongest animals in nature for its size, an earthworm weighing less than one-thirtieth of an ounce may move a stone weighing as much as two ounces. The family name, annelida, derived from the Latin word anellus (a ring), is graphically descriptive of the earthworm, whose body is formed by a series of from 200 to 400 muscular rings (more or less, depending on the species), closely woven together to form a tube of great strength, streamlined to the ultimate for functional performance.
Considered primarily, man himself is an organism of bone and muscle, brain and nervous system, organ and tissue, integrated around a digestive tubethe alimentary canalabout thirty feet long. The earthworm is a digestive tube alone, stripped of all external incumbrance which might interfere with its life-function of digestion and equipped with just enough instinctive intelligence to carry out its feeding activities without too fine discrimination.
Thus, everything which opposes itself to the blind attention of the earthworm becomes something to be devoured. When a stone too large to swallow is encountered, the worm eats its way around, giving the surface a chemical treatment in passing and possibly sucking off a few choice morsels from the weathered surface. If small enough, the particle is swallowed, to serve as a millstone in the gizzard while being subjected to the solvent action of acids and alkalies so abundantly provided in the digestive secretions. If a piece of tough cellulose, such as dry leaf stem, twig, or bit of wood, is met with, it may be coated with a saliva-like secretion and left to soften (perhaps for days or weeks), later to resume its journey of disintegration and digestion through the tubular intestinal mill. Figuratively speaking, the worm says "the world is my oyster," and then proceeds literally to swallow it with everything it may contain.
To be more specific, in action the earthworm employs the principle of the hydraulic drill, softening the earth in front of it, if necessary, with its secretions and sucking it into its mouth. Thus, blindly, the worm eats its dark way through the densest earth, including tough, compact adobe and clay soils, riddling and honeycombing the soil to a depth of ten feet or more with aerating tunnels or burrows, as it swallows the earth with all that it containsdead roots, vegetable and animal remains, bacteria, the minute and microscopic vegetable life of the soil, and mineral elements. Being truly a blind dweller of the dark, highly sensitive to light, the earthworm is a nocturnal animal, coming to the surface at night to feed on organic litter. By day it pushes slow tunneling operations below the surface, the softened and almost liquefied material finding its way into the storage space of the worm's crop.
Paul Griswold Howes, Curator of Natural History at the Bruce Museum of Natural History, gives a concise statement of the feeding habits of worms in his wonderfully interesting book, Backyard Exploration, as follows:
Worms are the most numerous at the surface of the ground at night... They come to the surface to feed, as they are truly nocturnal animals... They do actually consume large quantities of vegetable matternot living leaves and grass, but the dead and dying vegetable matter that lies upon the ground. Holding fast in their burrows by the tail-end, the worms reach out in all directions, stretching themselves to great lengths and grasping bits of food, which they pull below the surface. Here, part of the material is eaten, while vast quantities of it pass into vegetable mould that helps to make other plants grow. [Editorial note: All vegetable remains not immediately consumed, are eventually eaten and pass through the alimentary canals of worms in their final transformation into humus or soluble plant food.]
In addition to the vegetable matter which worms eat, great quantities of soil also pass through this vast army. From this soil they assimilate what is useful to them, leaving the remainder each night upon the surface in the lobed and familiar castings which everyone has seen. Stop for a minute to consider the countless individual worms which inhabit every acre of ground. Think then of the weight and depth of a single year's castings that are left upon the surface and you will begin to realize that the worms are actually responsible for the ploughing and turning over of the earth as the years go by.
Continuing our journey through the earthworm, all the ingested materialvegetable matter, animal matter, living and dead bacteria, mineral earth, small stones, etc.passes into the crop and thence into the gizzard as a semi-liquid, plastic mass, carrying its own grindstones. In the gizzard everything is subjected to the grinding, disintegrating and mixing action of this efficient organ, as the abundant digestive juices are poured in to exert their chemical and solvent action. No form of organic material escapes, for the digestive secretions of the earthworm are similar to those of the higher animals, including the human family. Carbohydrates, fats, proteins, celluloseall are grist for the mill of the earthworm; for anything that cannot be digested is at least so finely comminuted that no structural form remains.
Special mention should be made of the highly remarkable calciferous glands which are located in the walls of the esophagus of the earthworm. Nothing like them is known in any other animal. These calcium-secreting glands pour out abundant quantities of fluid rich in calcium, which exerts its neutralizing action upon the acids of the organic and inorganic mass of material which daily passes through the alimentary canal of the earthworma quantity which may equal or exceed its own weight every twenty-four hours.
The anterior one-third of the worm's body contains the vital organs and organs of the digestive system, including the calciferous glands, crop, gizzard, and reproductive organs. The remaining two-thirds contains the intestine. As stated before, the entire worm is comprised in a muscular tube of from two hundred to four hundred strongly contractile muscular rings, the number of rings varying in different species.
Continuing with the digestive process, after being discharged from the gizzard into the intestine, the material is subjected to further mixing action as it is moved slowly along the alimentary canal, taking on valuable added elements from the intestinal and urinary secretions in which it is continually bathed. Particularly valuable is the admixture of the urinary secretions, on account of the ammonia content. In Principles and Practice of Agricultural Analysis, Dr. Harvey W. Wiley states:
A considerable portion of the ammonia in the soil at any given time may also be due to the action of worms, as much as .018 per cent of this substance having been found in their excrement [castings]. It is probable that nearly the whole of the vegetable matter in the soil passes sooner or later through the alimentary canal of these ceaseless soil-builders, and is converted into the form of humus.
In its passage through the worm, whatever nutriment that may be necessary for the worm's own body-building and functioning is absorbed from the humidified, semi-liquid, and emulsified material. After having performed this nutritional function, the material is finally ejected as castingssuch finely divided, thoroughly homogenized earth that only chemical analysis can resolve it into its component parts. In other words, the ultimate end-product of the activity of earthworms is humusthe clean, sweet-smelling substance of new-turned earththe bedding, rooting, and growing material of life itself.
In considering the soil-building possibilities inherent in harnessing the earthworm, the subject matter naturally falls under two main headings, viz: "Why It Can Be Done" and "How It Can Be Done." The preceding sections have been introductory to these two divisions. As a preliminary generality, we might say, "The reason it can be done is because it has been done." The remaining chapters of this book are really an elaboration of this generality.
At this point we feel justified in a brief digression to consider the practical purposes of soil-building, as we conceive it.
Collectively, we think of man as the master of the earth, through his universal adaptability harnessing, controlling, and directing the forces of nature. Through this adaptability, the present-day environment of man has become the entire earth. Thanks to his ability to comprehend, direct and utilize the forces of nature, he can now live in comparative comfort wherever there is air to breathe. Nevertheless, today and in all the days to come, each individual is encompassed by his own particular environment and must work out his own salvation in that environment.
Philosophically, we listen to the full-bellied poet blithely sing, "I am the master of my fate, the captain of my soul." But until the individual can paraphrase the poet with a more literal and practical statement, "I am the master of the earth, the captain of the soil," he is liable to live in insecurity and fear of the future.
Securitywhat a comforting word! Security means adequate fooda roof over one's headclothes on one's backa place in the sunfreedom from fearno apprehension for the future. To the individual who desires surely to build security for himself and his loved ones, we hope to bring a knowledge of the means through which he may become the literal master of his own earth.
All the necessities, comforts, satisfactions, and luxuries of civilization wait upon the production of foodand food comes from topsoil. As a master-builder of topsoil throughout the ages, the earthworm in nature has played a leading role. Under scientific control and intensive propagation, the earthworm is destined to play a major part in the future development of topsoil and its maintenance at the highest point of productive capacity.
The topsoil of the future, beginning with the immediate present, will be built by man exactly to meet his balanced food requirements. Working intelligently with the same tools, materials, and forces with which nature has worked throughout the ages, but in highly accelerated tempo, each individual, here and now, may begin to build his own soil. Whether the individual works with a single flower pot or window box, a few square feet of earth in a city yard, or in a roomy garden, on orchard or farm, each man, woman, and child can put the earthworm to work, with all the allied forces of nature and cheaply abundant materials at hand, and begin to build security for all the tomorrows of the future.
The crowding populations of the earth stand on the last frontiera new frontier. Circling the globe, they have met. There are no more horizons, marking the boundary of a new and better Promised Land. Among conflicting ideologies and changing social systems, a basic fact stands out: We cannot move east or west, north or southhere we stand and must stand.
At this point, the reader may appropriately ask a few questions: What is this new frontier, upon which I am apparently standing? Where is it? I am anxious to explore it, adapt myself and build security for me and mine. And, incidentally, where do earthworms come into the picture?
The new frontier is literally beneath our feet. Layer by laver, right down to the bedrock, the ancient remains of buried continents lie sleepingthe inexhaustible parent material of new and fertile virgin lands to be awakened and roused to verdant life through the knowledge and mastery of man. This new frontier is not a figure of speech; it is an actual, physical factand each individual can go to work at once upon his own particular spot of ground, be it small or large, and have the pleasure, satisfaction, and profit of enjoying his own new earth which he, himself, has helped to create.
When the struggle for the mastery of the earththe actual physical occupation of the earthis over, vast changes will take place, are already taking place. Among the changes very definitely in evidence is the movement of city and urban populations toward the land. Spurred by necessity and a universal awakening to the importance of the soil, millions of people are turning toward the establishment of themselves upon the land, either small plots or more extensive acreage, according to their ability to acquire. They are seeking security through the development of a subsistence-homestead as a vocation or avocation.
The wise man or woman will not procrastinate, but will begin to plan now to occupy a little piece of earth, or a big piece of earth, and learn how to utilize it to the best advantage. It is not necessary to seek expensive land, highly developed and fertile. Through simple and easily mastered methods of soil-building, utilizing earthworms and allied forces of nature, the land-dweller can build his own good soil in any quantity necessary to meet his needs.