Ploughman's Folly Ploughman's Folly - EcoPort

e richer by the quantity of decay products that had been accumulated in it. As organic matter decays, mineral
plant-foods are released, as are also the additional elements which make up the organic compounds of which the
living material had been composed. Depending upon the character of the organic material, decay may take place
quickly or slowly. In either case, unless there are roots present at the time the decay products are set free, these
used plant-foods are almost certain to be flushed out of the soil by the very first rainfall. The only certain way to
prevent this loss is to have roots of growing plants always present when decomposition is going on in the soil. On
land that is left undisturbed, nature takes care of this. Roots are always present; therefore, no plant food is leached
away.
On the farm, these salvaging roots may be those of beans, cucumbers, or any other crop the farmer wants to grow.
The roots of such crops will gratefully absorb all the decay products they can get. It is a reasonable assumption
that the soil solution these roots pick up from decaying organic matter is different from that that they would find
available in pure mineral soil where nothing is rotting. Decaying material in the soil enriches the soil solution, so
that each unit of liquid can supply several times as much plant food as the same quantity of water from soil not
enriched by decay. That is only common sense.
It follows that the more decaying material there is in the soil, the richer the solution these roots pick up will be; the
richer the soil solution carried in by roots, the richer in minerals the plant sap will be. From this point it is easy to
assume that variations in the richness of the plant sap may affect the attractiveness of the plant for its customary
parasites. A greater proportion of minerals in the sap may result in its carrying less sugar, and a decrease in sugar
content may easily make the plant sap distasteful. Possibly cucumber beetles, for example, could be starved for
lack of palatable juices, even when their host plant is enjoying the richest possible food from the decay in progress
in the soil.
Such a theory is not entirely without foundation in science, even though no specific research has been devoted to
it. We do know that variations in internal juices of plants are produced by variations in the fertilizer treatment and in
the available moisture of the soil. This fact was established in 1918 by Dr. Kraus and Dr. Kraybill, whose report has
been used by a generation of students as a reference work in horticulture. [E. J. Kraus and H. R. Kraybill,
Vegetation and Reproduction, With Special Reference to the Tomato, Oregon Bulletin 149, 1918.] There is no
question that changes in plant composition are produced by changes in the nutrients available in the soil. We
cannot, of course, know how insects feel about having their favourite host plants overfed on minerals that originate
from decay. We can only guess, from the fact that they prefer the scantily fed plants to those that are better fed,
that the richer sap is less palatable to the insect.
If this theory is tenable, the human race is extremely fortunate. It becomes possible, because of this relationship
between the insect and its food supply, to improve the human food supply by the very method that will starve the
insects.
Apparently diseases yield even more completely to the environmental conditions which are most favourable to
plant growth. I am unable to advance, as tenable, a reason for this. It appears, however, that the leaf surface of
fully nourished plants is better fortified to prevent the entrance of infections. That there is a difference in texture of
the leaf surface of well-nourished plants compared with those growing on thin land may easily explain their better
resistance to disease. In this connection, the natural resistance of healthy, well-nourished plants becomes entirely
logical.
It is reasonable to believe that insects and diseases thrive only in a suitable environment, just as do other living
things. Further, it appears that the environment that is best for the disease and the insect is poorest for the host
plant; and the conditions that favour the host plant's development are intolerable for insects and diseases.
Scientific men with whom I have discussed this theory are not inclined to agree, because they still think the type of
soil would be an important factor and doubt that the experience would be the same under other soil conditions. My
contention is that the one determining condition is the surface incorporation of great quantities of organic matter,
that any type of soil so treated would bring similar results -- provided other conditions were no less favourable than
they were for my 1940 tests. (It can be said truthfully that the seasonal conditions from July 12, 1940, to frost were
such that many other plantings of beans had to be abandoned in the neighbourhood where my beans thrived.)
Ch. 13: Weedless Farming
I AM fully aware that it seems fantastically improbable to say that we should ever be able to farm land without
trouble from weeds. Weeds have been keeping farmers busy for so many generations that they are taken for
granted. In all of our farm planning, we have regarded weeds as a necessary evil; and moralists may even
consider that weeds are a blessing, for the work necessary to check their growth keeps farmers out of mischief.
Thus unthinkingly we have accepted weeds as inevitable. But perhaps they are not inevitable. Perhaps they may
be more vulnerable than we think. Like every other living thing, each individual weed must die at some time. None