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 plant feeding.
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