The soil is a great chemical laboratory, but exact knowledge of all its processes doubtless would enrich the farmer's vocabulary more than his pocketbook. We are concerned in knowing that lime's field of usefulness is broad in that it is an essential plant food and provides the active means of keeping the feeding ground of plants in sanitary condition. We want to know how it comes about that our soils are deficient in lime, and how we may determine the fact that they are deficient. We wish to know the relative values of the various forms of lime and how we may choose in the interest of our soil and our pocketbook. The time and method of application are important considerations to us. There are many details of knowledge, it is true, and yet all fit into a rational scheme that shows itself to be simple enough when the facts arrange themselves in an orderly way in our minds.
Lime cannot take the place of nitrogen, nor phosphorus, nor any other of the essential plant foods. It is not a substitute for any other essential factor in plant growth. It would be folly to try to depend upon lime as a sole source of soil fertility. On the other hand, we have learned very definitely within the last quarter of a century that it is foolish to depend upon commercial fertilizers and tillage and good seeds for full production of most crops from great areas of our farming country that have a marked lime deficiency. The obvious need of our soils is the rich organic matter that clover and grass sods could furnish, and their fundamental need is lime. Most farms cannot possibly make full returns to their owners until the land's hunger for lime has been met. The only question is that regarding the best way of meeting it.
CHAPTER II
THE LIME IN SOILS
Limestone Land. Soil analyses are serviceable only within certain limits, and in the case of the normal soils that comprise the very great part of the entire humid region of the United States the practical man gives little heed to what special analyses might show him when deciding upon the purchase of a farm. He does know, however, that a limestone soil has great natural strength, and recovers from mistreatment more readily than land low in lime. It has staying powers, and is dependable, unless through natural processes the lime leaches out or loses availability. All limestone areas have gained reputation for themselves as producers of grain and grass.
Other Calcareous Soils. It is not only the limestone areas that stand high in esteem. There are types of soil with every varying percentage of lime down to clear sand or to peat, and some of the types are finely calcareous, containing such a high percentage of lime that nothing more could be desired.
The actual percentage is not the determining factor, a clay soil needing greater richness in this material than a loam, and a sandy soil giving a good account of itself with an even less total content of lime, but in its way the particular soil type must be well supplied by nature with lime if its trees and other vegetation bear evidences of its strength and good agricultural value.
Natural Deficiency. It is interesting to note the differences in evidences of prosperity that are associated with lime percentages. The areas that are able to produce the vegetation characteristic of calcareous soils are obviously the most prosperous. The decidedly lime-deficient sections, advertising their state by the kind of original timber, and later by unfriendliness to the clovers, do not attract buyers except through relatively low prices for farms. Such areas are extensive and have well marked boundaries in places.
It does not follow that every farm in such limestone valleys as the Shenandoah, Cumberland, and Lebanon, or in the great corn belt having a naturally calcareous soil, is prosperous, or that a multitude of owners of such lime-deficient areas as the belt in a portion of southern New York and northern Pennsylvania, or the sandstone and shale regions of many states, have not overmatched natural conditions with fine skill. We treat only of averages when saying that a "lime country" shows a prosperity in its farm buildings and general appearance that does not come naturally and easily to any lime-deficient territory. In the latter a man rows against the current, and if livestock farming is not employed to furnish manure, and if the manure is not supplemented by tillage and drainage to secure aeration, or if lime is not applied, the land reaches such a degree of acidity that it loses the power to yield any profit.