One of my biggest questions regarding electroculture is the distance that the electric field is effective.  It’s a bit of a difficult problem to wrap my brain around because soil science  is a complex topic on its own.  Deliberately adding electricity to the mix makes things really wacky.  In this post I would like to share with you some of the factors that affect the effective distance with regards to electrical stimulation of plants.

Let’s begin with the basics.  In case you didn’t know, when electricity is injected into the ground, it can travel great distances.  While this is theoretically true, the strength of the field will be attenuated or reduced as distance increases.  Other factors that can come into play are:

  • Soil type
  • Cation Exchange Capacity (CEC)
  • Soil chemistry
  • Moisture content
  • And more..

Throughout the early part of electroculture’s history, earth batteries were the primary

Now, in modern times, we have many more power options available.

Here’s a picture showing the effects of decreasing electric field strength on plants:

Electrified broccoli - different field strengths and their effects

Effects of decreasing electric field on broccoli plants. Field source is on the right side, just off-screen.

In the picture above, taken from a garden experiment in 2013 (See post: Backyard Garden Electroculture Creates Large Broccoli, Tomato & Eggplants), you can see the effects of a diminishing electric field.  In this picture, the source (positive electrode), is located off-page to the lower right, approximately 8 feet away from the plant in the center of the screen.  Based on this photograph, it can be estimated that a 5V DC source will have an effect on plants up to about 13 feet away, with the most prominent growth occuring within 10 feet.

Discussion

Despite what can be seen in the example above, I am still confused by the historical sources that state that electroculture (with Earth Batteries) can have an enormous effect of the growth of row-crops, when the electrodes are placed almost 200 feet from each other.  Perhaps the difference is due to the size of the plates that were employed.  From my understanding, the benefit of using larger zinc and copper plates in Earth battery construction is that it will provide a larger amount of current density through the soil region.  Essentially making for a very stiff 1.1 Volt source.

At the same time the layout of the electrodes probably makes a difference too.  In the 1st example, the electrodes were actually places quite close to each other (< 1 foot).   In this case the majority of the electric field is situated close to the electrode pair since there is nothing “pulling” the electrons over any real distance.  The spread of the electric field in this case is mainly a function of the source voltage.

Certainly there are other factors at play also, soil chemistry, cation exchange capacity (CEC), soil moisture, soil type, aggregate sizes and pore water, among other variables.   I’m just not sure.

 

Questions…

What do you think?  Am I correct in my analysis of the situation?

Has anyone tried replicating electroculture on row-crops?  How did they perform?  (Note: we have applied electricity to row-cropped sunflowers in the Sunflower+ experiment, but we placed our (compound) electrodes only 5 feet from each other.  Since our 1st round of results weren’t fully conclusive, we will probably keep the same configuration this spring.  On the other hand, if the team thinks that the land should be tilled, then we may change to a length-wise electrode layout and perhaps then we’d have some results to share.

Let us know your thoughts in the comments below.

 

  • Weber

    I am thinking lengh-wise would closer replicate the earth batteries.

    • I agree… We just decided to electrify this year’s sunflower+ plot using electrodes on either end, approximately 90 feet from each other.

      One question is – will their be a difference in the plants that are closer to the anode or cathode? Looking forward to seeing how things turn out!

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  • scott

    I always plant E/W in rows and charge N/S Other ways I ave found to in some cases retard the plant growth as well in extreme E/W charge electrodes actual plant tissue is retarded

  • Keith

    Something to consider: The presence of an electric field alone does not assist plants growth, it is the differences in potentials in the field that drive electric current, soil type and moisture effect resistance of the soil and consequently the amount of current. Of concern to plants is current density in the soil. No current consequently has no effect. Some current helps plant growth. Too much current hurts plant growth.

    Current = Voltage / Resistance. A given soil type and moisture and 10 feet of distance between electrodes will have a certain resistance. If the voltage remains the same, doubling the distance to 20 feet will double resistance causing the current to be half of what it was when the distance was only 10 feet. On the other hand, if you double the distance, and you double the voltage, the current will remain the same.

    Currents density between a positive and negative electrode is strongest along the path between a positive and negative electrode and drops off with distance away from the direct path between. Additionally, current density will increase right next an electrode. In a field, one can have a string of positive electrodes, and a string of negative electrodes. If one increases the voltage difference between the positive and negative strings, one should also increase the distance separating the stings. Given consistent soil and moisture, soil current densities should be fairly constant except for the soil immediately next to each electrode. Even then, more consistent current density close to electrodes can be had with more electrodes over a given distance on each string.

    If one plans on performing quality experiments with electric fertilizer, then one should consider looking into constant current sources using show rows, with different currents in different rows. and having plenty of space between rows so that current from one row does not overflow into other rows.

    • Hey Keith,

      Thanks for the insight… absolutely…
      The current density is an important piece, and it’s something that needs to have more research on, e.g. how much current density is best for a given crop.

      Furthermore, it’s of critical importance in earth-battery design since it’s the size of the plates that dictates the amount of available current. In some of my early experiments I used plates that were too small and didn’t get great results… at the same time, it could have been that the plant I was trying it out on wasn’t receptive to that amount of stimulation.