Therefore, the fertility of a soil is determined not only by the quantity of plant food it contains, but also by the condition of solubility the soil constituents are in.
Utah is the heart of the arid region of North America; her soils are heavy with wealth of plant food.
The most important cause of lowering the fertility of soils is the loss of plant food due to drainage.
But we can say that the amount of plant food in the soil is too small to be detected by such weighing as we can do.
The experiment shows that the top soil gives the plant something that it wants for growth and that it cannot get either from sand or from the subsoil; this something we will call "plant food.
It will be easy to find out whether these remains furnish any appreciable quantity of plant food.
Although the subsoil lay fallow for a long time it produced no plant food but is just as poor as the subsoil that has been previously cropped.
If it be plant food, it comes directly from the soil.
Soil may be supplied with all kinds of plant food in just the right amount and yet, if it is packed hard and is not watered, no living thing can take root in it and grow.
Much of the soil of the great deserts in the southwestern part of our country is rich in plant food.
Finally, when the storm is over and the river goes back into its channel, there is left on the surface of the valleys a layer of earth rich in plant food.
Plant food is taken up by the minute tree rootlets in solution and carried to the leaves where it is elaborated and then returned for use to the growing tissues of the tree.
It now remains to point out another important function--that of a green manure crop adding humus and plant food to the soil.
Plant food must be in solution and in the form of a film moisture surrounding the smallest soil particles in order to be available to the fine plant rootlets which seek it.
Scientists tell us that there is an abundance of plant food in most soils.
Obviously, therefore, only those compounds of these elements in the soil which are soluble in the soil water are available as plant food.
While I was not able to learn other facts regarding this case, I have little doubt that the washings from this floor had been carefully collected and taken to some receptacle to serve as a plant food.
Market gardeners rely chiefly upon stable manure for their supply of plant food.
The common method of producing sets is to plant a large quantity of seed on a small area of rather rich land and thus procure a great number of bulbs that are undersized, owing to crowding and lack of plant food.
Coal ashes, because they are coarser in particles and devoid of potash, do promote mellowness, and are valuable mechanically on a heavy soil although they do not contain appreciable amounts of plant food.
This deepens and cleans the land to the manifest advantage of the grain crop, but still the beet reduces the plant food in the soil and some change of crop should be made with reference to its restoration.
Your trouble probably lies either in the lack of plant food or of moisture in the soil.
It is wisdom and good business policy for farmers to study carefully this question of plant food and to learn what each crop is taking from the soil, so that it may be replaced.
By a fertile soil is meant one that has an abundance ofplant food in the proper proportions.
By the animal activities, some of the foods are at once decomposed into carbonic acid and water, which, being dissipated into the air, are brought back at once into the condition in which they can serve again as plant food.
But urea is not a plant food; for ordinary plants are entirely unable to make use of it.
Thus the bacteria come in as a necessary link to connect the animal body, or the excretion from the animal body, with the soil again, and therefore with that part of the circle in which the material can once more serve as plant food.
It is worth while to remember that there are ten essential elements of plant food.
When thoroughly rotted, the manure acquires a still larger percentage of plant food; it is more valuable, not only for that reason, but also on account of its immediate availability.
All this plant food, and perhaps one half more, can be drawn in a single load, while it will take ten such loads of stable manure to supply the same amount of plant food.
The function of these bacteria is to gather the nitrogen of the air and supply it as plant food.
These new ones are those needed by plants, and thus is plant food digested.
Now we have the chief articles of plant food, and it is necessary to know how they are to be used.
The term "plant food" has been frequently used, and should now be distinctly explained, for merely stating the chemical elements is not describing the food.
The more plants there are on an acre the less water there will be for each plant, and what is true of water is also true of plant food.
Mapes, he writes: "Salt was only effectual as a fertilizer in proportion as the soil contained accumulated supplies of plant food, either from previous manurings or from natural strength.
The above list will hopefully provide you with a few useful examples demonstrating the appropriate usage of "plant food" in a variety of sentences. We hope that you will now be able to make sentences using this group of words.
