As a matter of fact, more and better food material is supplied by plant foods and at a far less cost.
Residues of cherry and wheat constituted the only plant foods found in the pellets.
It is therefore no doubt well supplied with oaks, and plant foods are thus readily available.
Such a mixture of plant foods occurs in the soil, the composition of course varying with the soil.
The land may be lacking in one of these plant foods or in all; in either case a maximum crop cannot possibly be raised.
We learned also that lime is useful in improving the texture of the soil and in making other plant foods available.
The best method of determining what plant foods are lacking in the soil is to carry on some simple experiments.
Chemically, lime decomposes minerals containing potash and other plant foods, thus rendering them available for the use of plants.
A number of additional plots may be added if desired to test the effect of plant foods in combination.
Before answering this question let us see what amounts of plant foods these crops take out of the soil.