CHAPTER NINE

Blackman’s Numbers

The man chosen to find out was Vernon Herbert Blackman, professor of plant physiology at Imperial College in London. Blackman was no enthusiast. He was a specialist in the measurement of plant growth, the author of the “compound interest law” that still appears in textbooks, and he approached electroculture as a problem in measurement.

The field trials

From 1917 Blackman and his colleagues ran overhead-discharge trials on field crops at several sites: Miss Dudgeon’s land at Lincluden, the Rothamsted Experimental Station in Hertfordshire, and Harper Adams Agricultural College in Shropshire. Thin wires were strung about seven feet above the crop and charged to several tens of thousands of volts. The current that actually passed down through the air to the crop was tiny, on the order of a milliampere or less for a whole acre. The discharge was run for some hours a day through the early part of the growing season.

The crops were mainly spring-sown cereals: oats, barley and wheat. Controls were set at a distance to avoid drift, and in some seasons were themselves surrounded by earthed wire screens.

In 1924 Blackman published the summary in the Journal of Agricultural Science. Over six years he counted eighteen field experiments. Fourteen showed an increase in favor of the electrified crop. Four showed a decrease. The average result across all eighteen was an increase of about twenty-two percent.

The laboratory

Blackman knew that field plots are noisy, so he also took the question indoors. In pot cultures under glass, where soil and water could be made uniform, electrified cereals again tended to outyield the controls.

Then, with A. T. Legg and F. G. Gregory, he reduced the experiment to its simplest form: single barley seedlings in the dark, a charged point above each one, and a microscope to measure the growth of the young shoot hour by hour. A current almost too small to measure, around a ten-billionth of an ampere, produced a small but real acceleration of growth. Stranger still, the faster growth went on for some hours after the current was switched off. That paper was published in 1923 by the Royal Society.

What Blackman established

This is the high-water mark of the evidence for electroculture, and it deserves to be stated carefully.

A first-rank plant physiologist, with no commercial interest, using the best methods of his day, at official research stations, found that a high-voltage overhead discharge increased the yield of spring cereals in most trials, by about a fifth on average, and showed a corresponding effect on single seedlings under laboratory control.

It also deserves its limits stated carefully. Fourteen out of eighteen is suggestive, not conclusive, and the field plots were still not replicated and randomized in the way that would soon become standard. The effect swung widely from year to year: a large gain one season, a loss the next, on the same land with the same equipment. And a twenty percent increase, if real, could also be had from a bag of sulfate of ammonia, without poles, wires, insulators, a generator, and a man to mind them.

Those two problems, the inconsistency and the cost, would decide the matter.