When Physics Goes Farming

‘The desert shall rejoice, and blossom as the rose.’ — Book of Isaiah

I

A FARM is a factory where the energy of light is used to make cheap simple molecules into valuable complex molecules. In another sense it is a packaging establishment where energy from sunlight is bottled up in the molecules of matter and held for future use. Farming is thus both a chemical and a physical process. That chemists have had much to contribute to the development of new agricultural methods is well recognized; that farmers need physicists to aid them is equally true but not so obvious.

Agriculture, the world’s greatest industry, is still in the era of its development which corresponds to that of the sailing ship in transoceanic commerce. The continued existence of two billion humans depends on what the land produces, and two out of every three people draw their livelihood from farms, but farming still remains in most instances a backbreaking, discouraging process of slim and uncertain profit. An annual return of eighty dollars from an acre of land chosen at random is still considered princely; seventeen dollars is the average gross return. After long hours of labor, the farmer and his family may, if their sprouting seeds are not eaten by birds and insects, washed away by floods, blown away by winds, or withered by drouths, produce a crop for which the demand has vanished because of overproduction.

Perhaps the art of agriculture has not felt the need of scientific methods more acutely because it has always had something of the character of a free lunch. The passing motorist picking the farmer’s apples at the roadside considers himself merely sharing in the gifts of Providence. Seeds cost nothing, since any apple core in the street is filled with them; plant a seed, let the heavens water it and the blessed sun shine upon it, and pick your apples when they ripen! The newly embarked agriculturist frequently feels the same emotional response to the call of the soil. Twenty years later, if he is still farming, his response has usually been considerably modified.

The cheapest way often is not the most economical. The winds blow free across the seas, but it is cheaper to spend $10,000 on oil to send a liner from New York to Liverpool than it is to fit the same vessel out with $2000 worth of sails and accept the freedom of the winds. The original farmer merely picked his crops where he found them growing wild, as the first boatman floated on his log wherever the current carried it. Then the farmer scratched his land and sowed his seed, and the boatman learned to paddle with a stick. When the boatman invented a sail, the farmer matched him with an irrigation ditch. Then the sailor called in the scientist to help him, or rather found the apparatus produced by science forced upon him by economic necessity. The farmer with ambition feels that he too has become very scientific during the last thirty years. His experiments with scientific farming are as yet, however, but as a chugging paddle-wheeled ferry compared to the steamboat whose smoke is now becoming discernible.

Plant growth has four basic needs: light, air, water, and a comparatively small supply of such chemical elements as magnesium, phosphorus, sulphur, silicon, and others. The plant takes from the air the materials which it needs most to build its structure. Since the chemical reactions within its cells must take place in solution, water is stored in them and the turgidity of these cells gives rigidity to the plant structure. Light furnishes the energy with which the plant abstracts carbon atoms from carbon dioxide molecules taken from the air. With these carbon atoms and hydrogen and oxygen atoms from water and air, the plant builds starches and sugars which furnish most of the chemical energy used by man. In addition to its edible components, the plant also synthesizes cellulose materials which man burns, saws, spins, and otherwise shapes to his advantage.

All this sounds very chemical, but once the proper fertilizing ingredients have been added to the soil (if not already present) the plant carries out these chemical operations most effectively, and the chemist comes into the picture largely in connection with utilization of the crop. The great primary problems of farming, apart from fertility, involve investigating and controlling temperature, light intensity, soil mechanics, and water application and disposal, all of which are problems of physics and its derivative sciences.

The full time of a few physicists is now being given to research designed to improve agriculture; the field would justify the attention of many more. The agricultural income of the United States was about $5,000,000,000 in 1935. With less land in use than at present, but with the use of improved methods, this income could be increased manyfold. Increasing agricultural efficiency is not essentially different from designing more efficient light sources or learning how to telephone greater distances — it merely requires coöperative research in a greater variety of sciences.

If fresh ripe cherries are desired in Maine in February, there are three ways to provide them. The fruit could be brought at high speed from Australia or the Argentine or anywhere else where cherries are ripe in February; improvements in transportation are needed to make such hauling profitable. Or the cherries could be raised wherever cherries will grow, picked whenever they ripen, and then kept until February by some method which would preserve them unchanged for at least six months — a cherry which cannot be distinguished from a fresh cherry is a fresh cherry to its consumer. Or the cherries could be raised in Maine in February by treating the cherry trees in some such way that they would feel June weather about them. All three of these methods are at present in promising stages of development, and t he principal requisite needed to make them economically practicable is cheaper energy. In fact, if electrical energy could be delivered to farms at the rate at which it is now sold wholesale to industrialists near large power-producing plants, a rate less than one tenth what the average farmer has to pay, the second and third methods would now be feasible and profitable. That rural power could be made cheaper by proper organization is emphasized by the fact that nine tenths of the average electric power bill is paid, not for power, but for the privilege of turning it on or off at any time.

The United States is woefully behind the times in farm electrification even for such obvious things as water pumping, wood sawing, and the thousand other tasks that for years have added to the drudgery of farm life. When a man saws wood by hand, he is earning five cents an hour, which is what it costs on the average to have electricity do the same job. In Switzerland 98 per cent of the farms have electric power, while in Sweden almost half of all farms are so equipped; in this country not more than 4 per cent of farms are wired for electricity, in spite of the fact that the United States uses four times as much electric power per person as the rest of the world and that its domestic and industrial power consumption is climbing steadily. On one farm of 600 acres in England only two horses are kept, while over sixty different uses are made of electricity. In Holland that picturesque feature of the landscape, the windmill, which has furnished cheap power for so many years, is rapidly being displaced by electric motors which are fed power generated from Russian coal. The number of windmills has been cut in half, and by going to the additional expense of importing coal the Dutch market gardeners have been set free from the vagaries of wind and weather to such an extent that they have been able to capture much of the fresh vegetable market of Great Britain previously held by Italy.

The use of artificial light to supplement rather than to supplant sunlight has been found of economic advantage, both to hasten and to retard the maturing of flowers and fruits. The sunlight falling on a square yard of garden surface costs three cents an hour to duplicate electrically, a figure which amounts to over $100 per acre per day. Artificial light may profitably serve to eke out sunlight on dark days and sometimes during the night, but electrical energy cannot compete directly with solar energy until its cost has been greatly decreased.

II

The chief practical use for artificial light at present is in advancing the maturing date of flowers. Forcing lilies for Easter is an old trick, and proper illumination will expedite blooming by as much as a month. Sweet peas have been made to bloom five weeks in advance of normal by means of artificial light. One type of clover which scientists of the Boyce Thompson Institute for Plant Research in Yonkers, New York, found ordinarily required two years to come to bloom was brought to flower in one tenth of this time under artificial light. Forcing by means of light appears more suitable than forcing by other means, as it is accompanied neither by a loss of color or fragrance in the case of flowers nor by a loss of color or flavor in the case of fruits.

Some plants thrive on a long working day, while others respond best to a short day. Chrysanthemums, which tend to bloom too soon for the best market, can be retarded by giving them extra-long days of growing under artificial light. Plants which bloom in midsummer like a long day; those which bloom in spring or autumn like a day of medium length; those which bloom all the year round appreciate shade once in a while when the days are long. Light judiciously applied makes flowers and fruits more brilliant and colorful. But lots of light must be used; the five or ten foot-candles of artificial light provided in the average living room is negligible compared to the two to ten thousand foot-candles a plant gets from the sun out in the open.

Filtered light may be useful, as some plants are injured by the heat content of solar radiation. Only one fifteenth of the energy in the light from the sun is of the proper colors to be used by plants; the remaining 93 per cent serves only for heating air and soil, and may burn delicate plant tissue. In the future we may see greenhouses with clear glass above, to let in as much radiation as possible, and with internal amber glass shields over certain plants to protect them from the heating rays while allowing the useful colors to pass.

That all colors of light are not equally effective in promoting plant growth may be inferred from the fact that leaves are bluish green in color. The absorption of light by chlorophyll and by both dead and living plant leaves has been carefully studied with the spectroscope, and red has been found to be the color most vigorously absorbed and utilized.

By growing similar plants under conditions identical except as to illumination, one group of plants being under blue light, another group under red, with others bathed in infrared and ultraviolet respectively, it has been found that such widely differing varieties of plant life as the buckwheat and the green scum which grows in stagnant ponds respond similarly to light stimulation. Biophysicists have found that yellow light from an incandescent lamp will stimulate growth half again as fast as blue light from the same source, while a given amount of yellow energy from a sodium vapor lamp produces more than twice as much growth as the same amount of bluish energy from a mercury arc lamp.

Pure blue light appears to retard plant growth, while ultraviolet light is definitely injurious. On the sides of high mountains, plants which in the valleys below grow luxuriantly are often found flourishing but stunted, an effect attributed to the smaller cell structure promoted by the high intensity of blue and ultraviolet light at high altitudes. The edelweiss of the Swiss Alps is a small plant, but when brought down into the valleys it grows tall and bushy. When taken indoors and illuminated with blue and ultraviolet light, it grows dwarfed and spindly as on the mountain peaks.

A collector of tropical plants is said to have been presented, during a visit to Central America, with a small shrub known as the dwarf Panamanian milkweed, which was widespread in that region. On his return to the United States he gave it to a botanical garden and thought nothing more of it. A year later, when he visited the garden, its director told him that he would like to have his help in identifying a great vine several hundred feet long, which was climbing along a fence and threatening to encircle the entire institution. The collector could make nothing of it, and finally stated his belief that the vine belonged to an entirely new species. ‘That,’said the garden manager, ‘is your dwarf Panamanian milkweed.’ So great is the influence of physical environment on plant growth.

Most florists and hothouse vegetable growers who pride themselves on upto-the-minute greenhouses are supporting inefficient, expensive, and archaic structures. A greenhouse is supposed to be an illuminated energy trap. Light of most of the wave lengths received from the sun penetrates glass, and once inside the greenhouse it is absorbed by plants and soil. As the temperature within the structure rises above that of the outside air, its inner contents begin to radiate heat, but the heat waves radiated from objects so cool cannot penetrate glass. Since the entrapped radiation cannot escape, it must devote its energies to building up the internal temperature of the greenhouse.

On such valid principles of physics was the greenhouse designed, but all too seldom are these principles followed correctly. There is little point in having glass on the north side of a greenhouse, for the north half of the sky gives only one ninth as much radiant energy as the south half when the sun is shining, and more heat is conducted out through the glass than comes in. Scientists of the Boyce Thompson Institute have designed a new type of greenhouse which turns out to be cheaper to construct and to operate than the ordinary type, and far more efficient. This greenhouse contains little glass, but what glass there is is so disposed as to catch every possible ray of the sun, and to cut down losses by reflection. One half the roof, both ends, and the back wall of the greenhouse are all of sheet metal stuffed with sawdust for heat insulation. No crack is allowed in the walls, for out of this would escape the heat which is to come not only from the sun, when sunlight is available, but from electrical sources as well. The usual greenhouse designer has a custom of lapping the panes of glass like shingles, probably acting from a feeling that plants must have fresh air, but this process leaves tiny spaces through which heat pours from the inside of the house.

The Boyce Thompson scientists use electric light to lengthen the growing day of the plants when this is desirable, and so add as much as four hours of extra growth each day. When the temperature falls below the desired value the high-power lamps are automatically turned on and the heat from these keeps the hothouse warm. Even with expensive domestic power, the cost of the four hours’ extra light and the entire heating was only thirty-six cents per day for a large greenhouse. In this way June is brought to the plants in January, and flowers, vegetables, and fruits can be raised profitably out of season when they command relatively high prices.

With such extensive precautions against external weather variations it is necessary to provide artificially what before was always present as a gift from nature — gas for the plants to breathe! In one corner of the Boyce Thompson greenhouse a block of solid carbon dioxide (dry ice) was buried in sawdust, to evaporate slowly and furnish the gas which to the plants means fresh air. A tiny fire of any sort, to burn the excess oxygen given off by the plants while forming the carbon dioxide they need, would do as well and would give additional heat, but would require more attention. Scientists of the Smithsonian Institution have recently developed a method by which changes in the carbon dioxide content of the air as small as one part in a million can be measured by using infrared rays and the spectroscope.

Though a large greenhouse can be kept at summer temperatures fairly economically with steam heat, electric heating is more satisfactory, as it can be applied rapidly where it will do the most good, can be thermostated readily to keep any desired constant temperature, and can be used in the form of light so as to increase growth. To heat the present-day greenhouse elect rically is expensive, but with proper design to conserve heat, and with the cost of power cut down, it should be profitable to control in this way the weather over acres of gardens near the centres of population. A tomato plant twentyfive feet high and forty feet wide, unaware that February has come to New England outside, is a profitable investment, especially if it bears twenty times the normal yield and the fruit matures in half the normal time.

III

The principal part of any farm is usually considered to be the soil. That soil is not essential is shown by the experiments which have been undertaken by a number of scientists who have sprouted seeds on blankets of moist excelsior or sawdust dipping into trays of chemical-laden water. Twentyfold increases in yield of various crops from strawberries to hay are reported, and it seems reasonable to expect that much of the vegetable and fruit gardening of the future will be carried out in this way. Under these conditions an acre of land becomes merely a space on the earth’s surface which can be occupied, and the stoniest Vermont hillside, if it be near a large city, may become more valuable than a rich but isolated California valley. When soil is depleted and the farmer starts replenishing it with expensive chemicals, he begins to realize that the main contribution of soil is mechanical; it holds the plant upright in a given spot, keeps it from being blown or washed away, and allows water to seep slowly in thin films to its rootlets. However, the chemicals provided by nature, as well as the sunshine, air, and water, are too valuable to neglect entirely, and field crops in the open will always remain of importance.

At the University of Saskatchewan a single grass plant has been found to grow roots at the rate of more than two miles a day. A two-year-old plant was found to have a total root length of over three hundred miles, though no single rootlet was over seven feet long. The soil must be a sponge through which these roots can penetrate, and should bathe them in the nutrient solutions carried by the soil water.

Ploughing is a problem in mechanics, but ploughs have been designed since the beginning of time by trial and error rather than scientifically. Even the modern tractor drawing a gang of ploughs behind it leaves much to be desired as far as efficiency is concerned. Electric ploughs with motors of 125 horsepower, drawing energy from their own transformers which are fed from 30,000-volt transmission lines, are common in France. In other areas seven ploughs fastened together plough a strip eight feet wide to a depth of eighteen inches, and are able to cover thirty acres in a day when pulled by 200-horsepower motors. The day of the streamlined plough is coming!

The physics of the soil has been the subject of many books, but much is still unknown about it. Farmers know that some crops prefer a loose sandy soil, and others a heavy clay soil, but if they have a field which changes in composition from one part to another, and horse beans happen to be the crop of the neighborhood, horse beans are likely to be planted in the whole field. The methods of the present make any other course impracticable; with the methods of the future, ten times as many horse beans will be grown on the most suitable tenth of the land, and the rest will be devoted to other crops or lie fallow.

The chemistry of soils has many dark corners still to be illuminated. Concentrations of certain elements so small as to be difficult to detect by ordinary analysis appear to be absolutely essential to plant growth. The spectroscope is being increasingly used to detect the extremely small amounts of important elements present in soils. In some regions of the West, vegetation in certain areas is spindly and apparently slowly poisonous to animals which graze on it. Investigation has shown that this land has a deficiency of sulphur and an excess of selenium. Selenium atoms are chemically much like sulphur atoms, and although a plant can tell the difference, it will absorb selenium, which appears almost as good, if it cannot get the sulphur it wants. But the selenium is very harmful to animals. With the usual methods long and tedious analyses are required to measure the sulphur and selenium contents of soils. But since the sulphur and selenium atoms give out very differenl spectrum lines, the spectroscope can be used quite readily to differentiate these substances.

Each pound of vegetable matter produced by a plant requires the transpiration on the average of forty gallons of water. The yield of some crops is at certain periods extremely sensitive to water application. A variation of two inches in the July rainfall in Ohio is said to cause a variation of $13,000,000 in the value of the corn crop in that state alone.

A century from now a farmer who relies on rain to provide the water for his crops will probably be considered as old-fashioned as we consider the primitive man who harvested his crops wherever he found them in the wild. Rain is so likely to fall when it is not wanted, and not to fall when it is wanted. But floods and drouths are disagreeable only when kept apart; mix a good fat flood with a long shriveling drouth in the proper proportions, and excellent farming conditions result. Storage facilities are all that are required to do this. One of the things man is slowly learning in his gradual climb toward wisdom is that nature need not be accepted as she is at the moment, but can be smoothed out over a period of time and over an area of space, to make the ups and downs of life less severe.

The weather is a field of human interest for which physics must take full responsibility. Whether it rains or shines or snows depends on the physics of the atmosphere, and the meteorologists who dedicate themselves to following and predicting the vagaries of this most fertile topic of discussion are applied physicists of a most determined and interesting sort. Weather predicting a day in advance is gradually getting to be on a fairly sound basis, with more emphasis on the ‘fairly’ than one would like. Predictions made a week in advance are on a more shaky foundation. Predictions made a year in advance, covering long-term periods of drouth and dampness, are still rather in the hopeful stage, though great possibilities seem to be appearing as more data are recorded. The weather is very complicated.

One new development which shows great promise is the polar-front theory, lately incorporated by the United States Weather Bureau into its official methods of prognostication. This theory, which originated with one of a famous family of weather physicists, Professor J. Bjerknes of Norway, is proving a powerful new tool in weather predicting. Norwegians seem to excel in the study of weather, perhaps because they live where so much of it originates. Much intensive research is going on in the science of meteorology, and it is quite reasonable to expect that before many more years have elapsed far more precise and accurate shortrange forecasting will be possible.

In the midst of a host of pseudoscientific methods of long-range forecasting, which inevitably arise in connection with so important a subject as the weather, there are a few legitimate methods which are being developed as a result of real research. Dr. Charles G. Abbot of the Smithsonian Institution has for years been measuring the amount of heat received by the earth from the sun. Three Smithsonian stations in three of the most desert regions of the earth are recording the sun’s radiation daily. In almost treeless and waterless wastes, high up on mountain peaks, conscientious observers in Chile, in South Africa, and in western America have been taking records for many years. Although the heat received from the sun varies by only about one per cent, Abbot finds correlations between changes in solar radiation and temperatures at widely separated stations over the earth. By going back through his records, and by studying the records of earthly weather as recorded in the growth rings of trees which have been followed into the past for over two thousand years, together with other phenomena, Abbot has found what appear to be recurrent cycles in the weather which, if real, should be of great value in predicting longrange trends in the succession of years fat and lean. Such long-range predictions may in the end turn out to be easier to make than detailed predictions for two weeks in advance, and certainly they will be far more important.

As to producing rain from the sky artificially, Dr. W. J. Humphreys put the matter succinctly when he said that there are two kinds of rain-making schemes — those that won’t work and those that are too expensive to use. Nor are the requirements something that time will cheapen, either; the atmosphere is just too big for human control.

The greatest need for improving our knowledge of weather is improved means for collecting data. Airplane observations on physical conditions in the upper air are being carried out daily from a number of stations, but they are expensive and do not extend high enough. A newly developed method is the small free balloon, carrying a short-wave radio set with which it sends to earth a constant record of temperature, pressure, wind velocity, humidity, and other air data as it ascends mile after mile. Often the balloon and all its instruments are lost, but modern methods are cutting down the cost of such apparatus, and the information it sends back before plunging to loss or destruction makes the venture worth while.

Accurate prediction of frosts twentyfour hours in advance, a particularly ticklish job, is worth millions of dollars to California citrus growers. Smudge pots have been in use for orchard protection for many years. They act both by heating the atmosphere (most inefficiently) and by creating a pall of smoke which cuts down loss of heat by radiation from the earth to a clear sky. On the other hand, how amused the early settlers would be to see modern newspaper photographs of a Georgia peach grower burying cakes of ice under his trees in an endeavor to forestall early blooming in a warm winter.

IV

According to the estimates of government entomologists, insects each year cause a loss of nearly two billion dollars in the United States, a sum equivalent to the earnings of over a million men. Light, sound, and electricity are all being used to supplement chemical dusts and sprays in fighting insects on a physical basis. A highpower incandescent lamp suspended a few inches above a tray filled with kerosene-covered water in the centre of a sixty-acre field resulted in the capture of about twenty gallons of insects in the first four nights of operation, after which the number of insects caught gradually decreased as the supply gave out. The rancher who used the method claimed that the light protected his beans, corn, and tomatoes, and entirely eliminated the need of sprays and poisons. Corn protected in this way was found free from worms. Ten cents per acre per night spent for electric light decreased the number of insectdamaged tomatoes from nearly half the crop to practically none; in another instance $300 worth of electricity produced light which increased the value of the tomato crop by $2000. A difficulty with this system for general application is that some injurious insects are not attracted by light, while others which are beneficial and necessary may be so attracted. It may be possible in the future to raise such worthy creatures artificially in a form which is not attracted by light, and ‘Smith’s NonPhototropic Ladybugs’ may be a subject of future advertisements.

Insects can be killed by high-speed electrons shot from an evacuated highvoltage tube of a type designed by Lenard many years ago for experimental purposes of a different nature. This has been termed a death ray, but such methods would be expensive and limited in application. A more effective death ray has been found to be the simple sound wave given out by a large electrical transformer near Boston. The hum of this giant carried far through the night, and was apparently mistaken by male mosquitoes for the mating call of a particularly alluring female. Whatever the cause, large numbers of male mosquitoes appeared, only to be electrocuted and cast dead at the base of their electromagnetic Lorelei.

An electric fan sucking air into a bag placed under an electric lamp has been used to gather in a single night ten pounds of gnats, running about a million to the pound. A little bit of this sort of thing would go a long way in gnat circles.

The physicist is able to aid the plant physiologist and the geneticist in rapid development of new species. Mutations, those startling dissimilarities of offspring to parent, can apparently be greatly increased in number by bombarding seeds with X-rays or highspeed electrons. It is thought that the electrons set free inside the seeds by the colliding rays bombard the genes which control the characteristics of the plant-to-be. With mutations greatly increased in number, artificial selection can rapidly be applied to breed new types of useful crops.

Bulb growers on Long Island have already adopted new varieties of double gladioli and double narcissi which have been produced by exposing bulbs to X-rays. A scientist of the General Electric Company has suggested that orange trees which would resist the cold might be developed in this way. Many freak varieties of plant have been produced — most of them valueless from an economic standpoint, to be sure, but all of importance in studying the processes of plant reproduction and variation. Many plants springing from seeds which have been subjected to the rays are found to be stunted, while in some the life processes have been greatly speeded up. Grapefruit trees two inches high, for example, have burst into blossom at the tender age of five weeks. General Electric scientists have produced by the X-raying of bulbs, among other less desirable new varieties of lilies, a type of regal lily with nonshedding anthers, a quality much desired by florists. Such tentative results promise much for the future, but since for every Burbank there are a million farmers content to grow hay in the same rocky pasture that their fathers hayed before them, it is reasonable to expect that the agricultural revolutionist with the necessary Burbank-Edison combination of qualities may be slow in appearing.

V

Crop preservation developments that are now under way show vast possibilities. Chemical means of preservation such as smoking, salting, pickling, and preserving in syrups have long been used. Well-tested physical methods are: heating to kill bacteria and moulds, followed by canning and bottling; drying and desiccation; coating with wax or grease to exclude air; and refrigeration. These methods, while preserving material in edible form, have usually caused some alteration in the product. No cold-storage egg can ever be mistaken for a fresh egg. However, modern research is resulting in increasingly successful new methods of preservation by refrigeration, and products have been preserved for years with little detectable alteration from the fresh condition.

One of the most promising refrigerating processes is that developed by Clarence Birdseye of Gloucester, Massachusetts, since 1925. Birdseye noticed that, in the far North, fish and game which were kept frozen over long periods of time tasted quite fresh when thawed out. From this observation and previous work done by scientists he developed a process of quick freezing of fresh fruits, vegetables, meats, and fish, on which over one hundred patents have been granted. The basic idea of the Birdseye process is to freeze the fresh material quickly, so that large ice crystals which might rupture the cell walls do not form. Very low temperatures are used; rectangular packaged bricks of the cleaned food material held between two metal plates are rapidly chilled under moderate pressure to thirty degrees below zero. Another quick-freezing method is the ‘Z’ process, in which a finely atomized liquid refrigerant is used to remove the heat rapidly from the material being frozen. While some food materials do not respond well to such treatment, others after even as much as a year in storage have a flavor and appearance, as well as a vitamin content, which make them difficult to tell from the fresh article. More than fifty food products, from oysters and lobster meat to corn on the cob, when thawed after quick freezing have shown themselves deliciously edible.

While foods kept fresh by processes of this type can be obtained in most large cities, the cost of refrigerated display counters has been an economic factor preventing more rapid spread of the use of such foods. Research has already reduced the cost of such refrigerators by three fourths during the few years the method has been in existence, and the power required to operate them by four fifths. Quick-freezing methods should be carefully distinguished from old-fashioned ‘cold storage,’ and even from the freezing of meats and milk which has been customary on shipboard for years. The essential improvement is the rapidity of the abstraction of heat from the food being frozen, to avoid change of flavor, and the use of refrigerants much colder than ice. Cold storage was designed to prevent spoilage — the new methods are meant to preserve the quality of freshness indefinitely. Far from being less fresh than the so-called fresh fruits and vegetables purchased in city stores, the quick-frozen products are often fresher, having been cleaned and processed within a few minutes of harvesting.

An era in development of low temperature food preservation similar to that which radio went through in the years 1900 to 1925 seems imminent. To-day more than ten million dollars’ worth of quickly frozen food is being sold each year; as methods are improved, the cost of processing and storing the materials will decrease, and the economic importance of this industry should increase a hundredfold.

We may expect to see, before long, large mobile freezing plants waiting in field and orchard to freeze such crops as the cherry and strawberry at their ripest. During the remainder of the year the frozen bricks of fruit may be dealt out as needed, to stand in the cupboard until the flinty cold within them thaws, whereupon they gently collapse in the dish into a pile of ripe freshness.

Dehydration has long been used to preserve fruits like the prune and the apricot, and grass cured to form hay is as old as agriculture. It may seem strange that farmers can be taught anything new about hay farming after ten thousand years, but new methods of artificial curing now being undertaken show remarkable possibilities.

Hay is not merely dried grass; it is cured grass — by which is meant that certain changes produced by physical conditions of heat, humidity, pressure, and air flow other than mere loss of water occur in the plant material. Almost two thirds of the total grass weight must be evaporated as water vapor. Haying has always depended on the weather, but the age-old readymade methods of cutting grass and leaving it to cure in the field are gradually retreating before the application of more controllable physical processes. Three British experimenters have found that they could greatly expedite and cheapen haymaking, and get a superior product, by piling the wet and new-cut grass around a wooden duct, in such a way that hot air could be blown through the pile. Using a five-horsepower motor they found it possible to cure a forty-ton rick of hay in thirty hours during typical English days of rain and fog. The hay commanded a premium in the market, as cattle were found to relish it better than ordinary hay.

Fan-made hay was found two thirds as expensive to prepare as sun-made hay. The chief saving came from less handling of the hay, and smaller loss from weather. By installing thermometers in various parts of a large rick, the temperature changes, which are influenced somewhat by fermentation and curing of the hay itself, could be followed, and the experimenters were able to produce greenor brown-colored hay at will.

The silo is a piece of physical apparatus which produces, by the chemical reactions produced by fermentation, a highly nutritious animal food which will last all winter. Now comes the electric silo, with a current of electricity passed through the silage as the chopped green material is fed in by air blowers or belt conveyers. Up to thirty amperes of current are passed through the material, heating it and hastening fermentation. A silo described by R. B. Matthews holds 3000 cubic feet of food and requires not over 480 kilowatt hours for processing. The silage produced is of an improved character, for the lactic acid bacteria which transform the fodder into silage, much as cabbage is transformed into sauerkraut, are given an advantage over the heatdreading deleterious bacteria which impede the preservation process.

VI

The farmer of to-day is not apt to be interested so much in how to produce more and better crops as in how to dispose of the crops he has. Hence a most important consideration is new crop outlets. Many products previously wasted are made use of by the needs of new developments of physics. Acoustic treatment of rooms requires soundabsorbing materials which are now manufactured from such fibres as sugar cane from which the sugar has been extracted. Drain pipes made from previously useless plant products are being fashioned with newly developed machinery. Cotton textiles are being used in road building — the tar covering protects the cotton, and the cotton acts as a binder. For air conditioning we must have filters, ducts, insulating materials, and structural materials, many of which can be made economically from agricultural products. The spinning of rayon made from cotton is a physical process. The microscope and the polariscope are being used to test and grade textile fibres so that they can be used in extended markets.

Two of the greatest inventions still to be made are an efficient direct means of converting solar energy into some easily available form such as electrical energy, and some practicable and economical means of storing this energy. Plants have learned how to accomplish energy storage with an efficiency of about 1.2 per cent; this efficiency, though low, is better than that of the thermopiles and photocells which have been developed by science.

If methods can be developed for concentrating plant energy cheaply, so that it can be transported readily and used as a fuel which will compete with coal and oil, agriculture will take a great leap as an industry. Since earthstored fuels must inevitably become less plentiful as time goes on, and since the efficiency of processing of agricultural energy-containing products will inevitably improve, any process deserves careful consideration which will give a product whose cost is of the same order of magnitude as that of natural fuels, even though more expensive at present. Many chemists and engineers now consider not only practical but economically feasible a process which changes the starch from potatoes, corn, and other crops into sugar, and ferments this sugar into alcohol, which can then be refined to give a motor fuel. On a straight cost basis, petroleum motor fuels still have the advantage by a factor of three or four, but the alcohol products possess certain advantages which make their developers very hopeful.

Nearly seventeen billion gallons of gasoline were consumed in the United States in 1936. Experts of the Chemical Foundation have computed that to replace this with alcohol containing equivalent energy would require the processing of nearly seven billion bushels of corn. Since the nation’s entire output of corn in 1935 was only two billion bushels, if farmers want to continue to grow corn, and scientists can do their part in development work, a continuing and growing market should be available.

A cheap method of converting cellulose as well as starch directly into a concentrated fuel would assuredly put the farm in the lead as an energy producer. Then the entire cornstalk (or whatever plant is found to store sunlight most efficiently and rapidly), dissolved in great vats to give a liquid of high fuel value, would go forth to run the generating stations and the motor cars and locomotives of the nation, and the importance of the farmer to society would be even greater than it now is.

A great contribution of physics to the farmer may well be in the future, as it has been in the past, psychological. Surely the telephone, the telegraph, the radio, the moving picture, and the automobile have done much to make rural life more satisfying. But more important than all of these is the difference between the outlook of a man who has a stony field plagued with bugs which contains a few bedraggled spears of corn or cotton, a mortgage, and an overworked wife and family, and that of a self-respecting citizen whose land, even if only an acre, is able to produce an insured and profitable income. One of the things most likely to bring about this change of outlook is the application to farm problems of the methods of scientific research which have resulted so successfully in other fields.

As an editorial writer has observed, there are not many good wars in which a person may enlist, but the struggle against wild nature is about the best cause to which one may dedicate his life. The methods of science go to the root of farm problems; the methods of politics and economics, while necessary for temporary adjustments, can never do more than rearrange the surface aspect of things. One single basic scientific discovery can make all of the economic solutions to the plight of the farmer unnecessary. The man with the hoe should be nonexistent a hundred years from now.