THE THEORY OF MANURING

The food of plants consists of chemical elements, or rather, of numerous substances which contain these elements in greater or less degrees. There is not room here to go into the interesting science of this matter. It is evident, however, as we have



already seen that the plants must get their food from the soil, that there are but two sources for such food: it must either be in the soil already, or we must put it there. The practice of adding plant food to the soil is what is called manuring. The only three of the chemical elements mentioned which we need consider are: nitrogen, phosphoric acid, and potash. The average soil contains large amounts of all three, but they are for the most part in forms which are not available and, therefore, to that extent, may be at once dismissed from our consideration. (The non-available plant foods already in the soil may be released or made available to some extent by cultivation. See Chapter VII.) In practically every soil that has been cultivated and cropped, in long-settled districts, the amounts of nitrogen, phosphoric acid and potash which are immediately available will be too meager to produce a good crop of vegetables. It becomes absolutely necessary then, if one would have a really successful garden, no matter how small it is, to add plant foods to the soil abundantly. When you realize, (1) that the number of plant foods containing the three essential elements is almost unlimited, (2) that each contains them in different proportions and in differing degrees of availability, (3) that the amount of the available elements already in the soil varies greatly and is practically undeterminable, and (4) that different plants, and even different varieties of the same plant, use these elements in widely differing proportions; then you begin to understand what a complex matter this question of manuring is and why it is so much discussed and so little understood. What a labyrinth it offers for any writer--to say nothing of the reader--to go astray in! I have tried to present this matter clearly. If I have succeeded it may have been only to make the reader hopelessly discouraged of ever getting at anything definite in the question of enriching the soil. In that case my advice would be that, for the time being, he forget all about it. Fortunately, in the question of manuring, a little knowledge is not often a dangerous thing. Fortunately, too, your plants do not insist that you solve the food problem for them. Set a full table and they will help themselves and take the right dishes. The only thing to worry about is that of the three important foods mentioned (nitrogen, phosphoric acid and potash) there will not be enough: for it has been proved that when any one of these is exhausted the plant practically stops growth; it will not continue to "fill up" on the other two. Of course there is such a thing as going to extremes and wasting plant foods, even if it does not, as a rule, hurt the plants. If, however, the fertilizers and manures described in the following sections are applied as directed, and as mentioned in Chapter VII., good results will be certain, provided the seed, cultivation and season are right.

Previous: MANURES AND FERTILIZERS
Next: VARIOUS MANURES

SHARE

ADD TO EBOOK