The Why, Where and When of Plant Feeding
In the cave-man days men were not handsome
nor smart, but if you set one out in the wilderness,
he would fashion a club and get along. “Men were
men!” you say? Maybe, but, more important and to
the point, game and food were abundant.
It’s the same with plants. ‘Way back when-everything
just grew and grew and grew. And then the food supply
in the soil started to dwindle. Certain important life-sustaining
elements were practically exhausted.
Justus von Liebig, the great German scientist,
worked out his law of the minimum, best illustrated
by the short staved barrel.
In essence it stated that plants cannot
grow beyond the soil’s ability to provide all of the
elements needed by the plants and that the elements
in shortest supply in relation to crop needs would become
the limiting factor in plant growth and production.
Thus, if manganese is the element in shortest
supply in a soil and this supply is short enough to
be the growth limiting element, no matter how much nitrogen,
phosphorus, potash, or other plant food elements may
be available, plants would not grow beyond the limits
of the soil’s manganese supply.
This is still the thinking behind modern
Many tests and experiments have been made
by the U. S. Department of Agriculture, Bureau of Plant
Industry, and various state Agricultural Experiment
Stations to determine plant needs and the best way to
fill those needs.
Did you know……..The United States
Department of Agriculture many years ago reported in
Technical Bulletin No. 340 an experiment they conducted
with tobacco plants. They grew 10 plants in separate
containers, feeding one plant all of the plant food
elements scientists knew were required from soil for
normal plant growth. Each of the other plants was fed
exactly the same with one exception . . . one different
plant food element was left out of the diet of each
of the plants. The photograph above shows the results
of this test.
Plant feeding can be complicated. For
years the apprenticeship for gardening was so long that
only the more patient European people could be trained
to recognize the hunger signs in plants and the plant
food materials that might supply the plants’ needs.
When America’s gardening soils were leached and depleted
of most of their nourishment, Americans almost quit
home gardening’ entirely