Enhancement of Vegetation Growth
by using Negatively-Charged Air Ions
Improving the rate and size of plant growth by using negative-charged air ions is called Electroculture or Electro-horticulture.
This proven technology goes back nearly 100 years.
The following text is from a book published just after WWI.
Electrical Cultivation of Vegetation
The high frequency current, when sent through a network of wires above a plot of ground, has the peculiar property of stimulating the plant life in the earth beneath the wires. Just why this should be so is not definitely known; while various theories have been advanced, it is possible that one and all may be faulty and it is not within the province of this book to offer theories. The apparatus required for the cultivation of plants on a small scale is neither elaborate nor costly although it must be made rather rugged in electrical construction to withstand the strain of almost continuous operation for hours at a time.
In a later chapter the data for the apparatus required for the cultivation of a one acre plot in the open is given; in addition to this, notes on the conduct of experiments with potted plants indoors are given as are also a few suggestions for hot-house work with both vegetables and flowers.
The experiments have their commercial side as well as their purely experimental. Crops may be forced to an early maturity with a marked increase in the flavor and tenderness. Lettuce is particularly susceptible to the influence of the current, while radishes and beets follow closely. For fancy fruits and vegetables the process is productive of results which add materially to the profits ordinarily to be made.
Plant Culture with High Tension Current
There appears to be a decided scarcity of data covering the process of plant culture through the agency of electricity. The contributions on the subject have been anything but specific in nature and this is due, in part, to the fact that most of the experimentation has been carried on by private investigators who, for various reasons, do not seem disposed to make public the results of their research. In this country, the greatest progress has probably been made by the agricultural departments of several schools and colleges, and it is to the excellent bulletins from this source that the author is indebted for much of the data that led to some private experimentation. While the present discussion is based upon this experimental work, the author does not wish to pose as an authority on the subject and the remarks herewith are offered in the hope that they may lead to some private research on the part of the readers. An interchange of ideas and experiences is invited and it is felt that such a policy will be conducive to a broader presentation of the subject in later editions of this book.
While the art of electroculture is almost wholly in the experimental stage, still it may be said that the experiments are productive of really practical results and the apparatus necessary for the performance is not expensive, providing the investigator is content to begin on a small scale.
There are several methods by which plant life may be stimulated with the electric current and, in treating of the subject, the author will outline these methods briefly in order that the detailed descriptions of the equipment necessary in each particular case may be made clear. The construction of the apparatus involved will then be covered and it will be optional with the experimenter whether he constructs his apparatus or buys certain parts of it ready-made from manufacturers. The latter course is desirable in many instances as many instruments are rather difficult of construction and can be purchased ready for use almost as cheaply as they can be made in the home workshop.
The methods by means of which plant life may be stimulated with the electric current may be divided broadly under two headings: one, in which the rays from an electric lamp are permitted to fall upon the area under cultivation, and the other, that in which a high potential current is sent through a network of wires stretched over the plot of ground. This latter method may be further subdivided into two basic headings: One in which a high tension direct or low frequency alternating current is sent through the wires and, the the other, that which employs a high potential, high frequency current. The former is simpler and productive of very good results; the latter is the more effective and, in some cases its results have been spectacular.
Merely because the high tension discharge method was productive of the most encouraging results in the personal experience of the author this method will be discussed first of all. It is not claimed that this is the right or even the logical method; it simply "worked" where others failed in the case of one individual investigator who is naturally prejudiced thereby.
The subject under investigation was a bed of lettuce, 10 feet wide by 20 feet long. This was situated across a yard and 50 feet from the companion bed used for purposes of comparison. The two beds were boxed in with lumber and topsoil was taken from the same load for each; in fact, the conditions were as nearly identical as it was possible to make them. Four post were set up at the electrical bed, in the corners of the plot as shown in Fig. 86. At a distance of 5 feet from the ground, ten wires were spanned from cross-arms attached to the poles. The wires were carefully insulated with two porcelain cleats in series at the end of each wire and a common lead connected the span of wires at one end as shown in the illustration. A ground connection is made by means of strips of galvanized iron "chicken wire" buried in the earth beneath the bed. The aerial conductor is brought to a small shed or other shelter arranged near the bed under cultivation and in this shed the high-tension transformer is placed. The power wires from the electric lighting circuit are carried to the transformer shed and a switch is conveniently placed both at the shed and at the point where the wires leave the house or pole.
Caution Must Be Observed
The utmost care must be used to prevent the possibility of persons coming in contact with the span of wire over the bed, or indeed with either wire leaving the transformer secondary, as the voltage delivered at this point would produce a dangerous shock. To afford a safeguard in this particular, a fence should surround the plot and a contact be arranged at the gate in such manner that when the gate is opened a bell will be caused to ring and this will remind one to turn the current off from the transofrmer before entering the gate. This device is not difficult to design and it fact it may consist of one of the familiar release pushes such as are used on door jambs.
Actual Results Obtained
A most interesting report on electroculture experiments was made recently by Mr. T. C. Martin at a convention of electrical men and from this report it may be deducted that, of all the processes by means of which plant life may be stimulated, the one employing the high frequency current as its fundamental principle is the most successful by far.
The experiments mentioned by Mr. Martin were carried out at the Moraine Farm, a few miles south of Dayton, Ohio, and located in the celebrated Miami River Valley. The experiments were promoted by F. M. Tait, formerly president of the National Electric Lamp Association, and were in the immediate charge of Dr. Herbert G. Dorsey, whose work in this line has long been worthy of note.
"In preliminary tests, according to Mr. Martin's report," says the Philadelphia Inquirer, "small plots were marked off for exposure to different kinds of electrification. To insure that the soil of one plot was not better than that of another, top earth was collected, mixed and sifted and then was laid to the uniform depth of seven inches over the entire area." To quote further:
"In the soil of Plot No. 1 was buried a wire screen. Over the plot was a network of wire, stretched about 15 inches from the ground. Connecting the network above the ground and the screen below were several wire antenna [sic]. The screen was connected to one terminal of a [source of ions] and the network to the other ..... About 130 watts were operated for an hour each morning and evening.
"Plot No. 2 was illuminated by a 100-watt tungsten lamp with a ruby bulb. The light was turned on for three hours daily beginning at sundown. Plot No. 3 was illuminated the same way, except that a mercury vapor lamp was used. No. 4 had no artificial stimulation of any kind, being intended as a comparison between electrically excited plant growth and that of natural conditions.
"In Plot No. 5 was buried a wire network connected to the terminal of a 110-volt direct current. The positive terminal was attached to a small sprinkling can with a carbon electrode in its center. The can being filled, the water was subjected to electrolysis for several minutes. The plot was then sprinkled from the can, the theory being that the current might flow from the can, through the streams of water to the soil.
"Plots Nos. 6 and 7 were sub-divided into four individual boxes, two feet square, separated by porcelain insulators and arranged with carbon electrodes at each end. To these electrodes were applied both direct and alternating currents.
"After radish and lettuce seed had been planted and germination had begun, the various methods of electrification were tried with extreme care. The result of the experiments showed that the plants in Plot No. 1 grew in every instance far more rapidly than those in the other beds and more than double the normal growth as shown in the unelectrified bed."
The comparative results obtained with the various processes may be noted in the table which follows, and it is interesting to observe that the high frequency current from the air ionization method takes the lead from the standpoint of weight of the edible portion of both radishes and lettuce grown under its influence:
|Radishes (10 plants selected at random)||Plot
|Plot 2 Ruby light||Plot 3 Mercury Vapor||Plot 4 Normal||Plot 5
|Total plant weight, grams||265.70||137.80||109.50||180.00||78.50|
|Edible portion, grams||139.50||57.40||40.90||79.40||31.00|
|Edible portion, percent||51.15||41.65||37.34||44.11||39.49|
|Tops and leaves, grams||120.50||75.50||65.90||95.00||41.50|
|Top and leaves, percent||43.35||54.92||60.18||52.77||55.66|
|Lettuce (10 plants selected at random)|
|Total plant weight, grams||67.00||52.60||56.60||46.10||31.30|
|Edible portion, grams||60.70||57.30||50.20||41.80||28.20|
|Edible portion, percent||90.59||89.92||88.85||90.67||92.10|