secure without difficulty, and unusable, such as is enclosed in the storehouse of rocks and particles and compounds. The soil analyst is not able to distinguish between these two forms, with sufficient accuracy to tell exactly what the plant may need at any given time. Neither his crucible nor his acids will help him, in any certain degree. When the test actually takes place in the field, the story is there told with language of no uncertain meaning. In a previous chapter the kinds of food were mentioned: avaliable, the not-immediately-available and the tightly-secured plant food.

Of course we cannot expect chemical analysis to show the differences between these forms. We are able only to determine the total amount of food present: the potential plant food, the food that is now and shall be available some day hereafter, as food for plants. An old notion is still held. A great mass of people still believe, that all that is necessary to know how to handle a soil is to secure its analysis that the plant food content may be ascertained. But, with our present knowledge, let this be accepted as certainty: the chemist can determine only the total quantity of plant food in the soil: the usable plant food plus the unusable plant food. And he cannot tell you whether it is available food or otherwise. It will be necessary for you to seek elsewhere than the laboratory for direction.

Analysis will help to some extent.-But an analysis of the soil may do great good. It may indicate in what direction improvement lies: whether tillage only is necessary that dormant supplies may be called into use, whether organic manures are best that the humus content may be increased, or whether mineral manures are likely needed that they may reënforce the plant food already present. While it is true these are indicative only,

their value is most noted when judiciously weighed and interpreted.

Investigation along this line indicates that a most important character in soil analysis is calcium carbonate, the lime carrier.

The following suggestions seem in accordance with this fact:

1. When calcium carbonate is scanty in the soil, liming the land is advisable.

2. When calcium carbonate is scanty in the soil, acidmade manures, like acid phosphate, super-phosphate, ammonia sulphate, are inadvisable, and manures, neutral in nature, like basic slag, ground bone, wood ashes, and nitrate of soda, should be used.

3. When calcium carbonate is plentiful in the soil, then the acid-made manures may be used.

4. When calcium carbonate is abundant in the soil, nitrification of organic matter will take place rapidly.

5. When calcium carbonate is abundant in the soil, useful bacteria will develop with ease.

Analyses should be extensive.-An isolated soil analysis is seldom satisfactory for the simple reason there is no standard of comparison. All values result through their measure with other standards. We get the great bulk of our knowledge by comparison. Every isolated subject is valueless unless it can be compared with some known quantity. For this reason, an isolated soil analysis is without value unless it can be compared with the known value of some other soil analysis. For this reason, then, soil analyses ought to be extensive and general, rather than isolated and haphazard. Such a system will give us general standards that will be valuable with every comparison.

Analyses of soil and subsoil should be made.-When

making a soil analysis, both soil and subsoil should enter into consideration, for the variation between these two, in chemical compounds, may compensate sometimes one

CORN GROWING IN SURFACE SOIL AND SUBSOIL
There is practically no growth at all in the raw subsoil

for the other. If a sand soil were analyzed, it might show very meager possibilities for crop production and especially this might be true if the subsoil were likewise of a sand nature, and at some depth. If, on the other

hand, just beneath the upper eight or nine inches of sand soil, a subsoil of clay formation were present, it follows that different conditions, of course, are ever at hand, so that a lack of any soil constituent in the soil might be furnished by the subsoil and, what would indicate, by analysis, a poor, or even barren soil, might, in fact, be a most productive one. This shows the necessity of con

Seeds are put into the ground and the soil compacted that moisture may be at hand to germinate the seed and to supply the needs of the little plant

sidering soil analysis from a broad standpoint, that every phase of the subject may be included.

The condition, as well as quantity, must be known.Furthermore, the condition of the plant food must be given its proper weight, fully as much as is given the absolute quantity of plant food. An analysis might show that nitrogen, for instance, is present in the soil as ammonia or as nitrates. The latter would be more readily

usable by the plants. Then, too, if it were known that the plant food were held in a soil that is finely powdered, of good physical condition, well supplied with water, bacteria, and all factors incidental to the growth of this supply, we should prefer to stand our chances with a soil of this nature, with plant food in this condition, than where all opposite conditions were present.

Observe the soil itself. If you would get acquainted with this hidden plant food which you cannot see, you must take the soil, itself, into your confidence and then continue to observe the soil in the fields; to watch it as it produces crops of this nature and of that nature; to see how it behaves in summer and in winter or in wet seasons or in dry seasons: in short, you must not neglect this constant intimacy with the soil out of doors, as it does the work satisfactorily, or as it tries to do it under the circumstances with which you have enclosed it.

With this training, which you must give yourself that you may learn to observe and to know the soil, and to reënforce the best knowledge by such information as general soil analyses-not in isolated cases, but of soil groups or soil types-you should be able so to acquaint yourself with your soils that you may know the best way of handling and treating them for each and every crop.