Character of Vegetation. The character of the original forests is determined much by the lime-content, and the practical man, when buying a farm, rates its productive power by the kinds of timber it has produced. The black walnut, ash, shellbark hickory, black and white oak, sturdily grown, evidence a soil rich in lime, while the pines, small blackjack and post oaks, and the chestnut are at home in non-calcareous soils. The latter class of lands gains nothing in lime as time passes, and the timber continues to be a sure index, but in the former class the surface soil may have lost enough lime to limit crop production materially while the trees continue to find in the subsoil all that they need. It does not follow that the land has gone down in value to the naturally lime-deficient class, but its power to produce is impaired, and will remain so until there has been restoration of its original alkaline state.

Sorrel and Plantain. We determine quite surely the state of the soil by observance of the vegetation that roots in the surface soil and the immediate subsoil. Sorrel is a plant popularly associated with soil acidity, but this is not through any dislike for lime. It has been observed growing in the edge of a heap. Its presence suggests acidity because it can thrive in a sour soil that will not produce plants of value which on even terms could crowd the sorrel out. There is constant competition among plants for food and water and space, and some of our worst weeds are not strong competitors of clover and grass where soil conditions are not unfavorable to the latter.

Blue grass, the clovers and timothy give a good account of themselves in a contest with sorrel and plantain where lime is abundant. This does not mean that the seeds of these weeds may not be so numerous that an application of lime cannot cause the clover and grasses immediately to take the ground to the exclusion of other plants, but it is true that the crowding process will continue until the time comes in the crop rotation that these weeds cease to be feared, and clean sods can be made. It is the absence of lime that permits such weeds to maintain their reputation for good fighting qualities.

The Clovers. Red clover can make growth in some soils that have a lime deficiency. If all other conditions are favorable, the lime requirement may exceed one-half a ton per acre of fresh burned lime and not affect the clover adversely, but farm experience throughout the country has demonstrated that when soil acidity is only slight and clover grows with difficulty, an application rarely fails to favor the clover in a marked degree. Experience has taught the land owners to fear soil acidity when red clover does not thrive where formerly it made good growth.

The prevalence of alsike clover in a farming region is indicative of lack of lime. This clover thrives in a calcareous soil, but is more indifferent to a small lime supply than is the red clover. As red clover seedings begin to fail, the alsike gains in popularity, and where a soil is decidedly sour the alsike is most in evidence. The latter has less value to the farmer, rooting nearer the surface of the soil, and making less growth of top, but it has gained in favor with farmers as soil acidity has increased.

The Grasses. Timothy is more resistant to acidity than red clover, but often fails to make a heavy sod where the deficiency in lime is marked. Rhode Island Bent, known as redtop, is less exacting, and where it thrives to the exclusion of timothy, or is in evidence in grass lands, the inference is fairly safe that a test would show that the soil is sour.

When Production Decreases. It is not a matter of any moment to the owner of a productive soil whether or not his soil would give an acid or an alkaline reaction under test. Returns from his labor are satisfactory. Some land in this class is not strictly alkaline. The man most interested in the effects of lime applications is the one who is not satisfied with yields. The tests for acidity have been so many throughout our eastern and central states that the owner of land which is not productive has reason for the presumption that its percentage of lime is too low. There is danger of error, and a scientific test is surer, but in most cases the land which has been reduced from a fertile to an unproductive state has lost its alkaline nature.

Naturally Thin Soils. Nature may be prodigal in supplies of nearly all the elements of plant food to land and yet skimp its supply of lime, but naturally poor soils are quite surely in the acid class. The exceptions in our humid region are not extensive. When improvement is planned for, involving additions of organic matter and plant food, the application of lime to correct acidity is the first requirement. If such land could be given the characteristics of a limestone soil so far only as the lime factor is concerned, the building up of fertility would be relatively easy. Liming must form the foundation of a new order of things. The ability to grow the clovers and to furnish rich vegetable matter to the soil, which naturally is poor in humus, rests upon lime application first, and then upon any supply of plant food that may continue to be lacking.