Nature's Provision. Soils are composed of pulverized stone and organic matter. Much of the original stone contained little lime, and the human race would become nearly helpless if there were no stores of supply in the form of limestone, chalk, marl, etc. The day would come when the surface soil could not produce our staple crops if its loss of lime continued, and a means of replenishing the stock were not at hand. The huge deposits of limestone that have not been disintegrated by processes of weathering are assurance that the soil's need can be met forever. The calcium and magnesium in the stone are in chemical combination with carbonic acid forming carbonates, and there is an additional mixture of other earthy material that was deposited by the water when the stone was being formed, but much limestone possesses an excellent degree of purity.

Confusion Respecting Forms. In the public mind there is much confusion respecting the sources and forms of lime most to be desired. Wood ashes appealed to people, especially in an early day in our agriculture, partly because the ashes were so universally present that tests had been made voluntarily and otherwise in millions of instances. The value of such tests had been obscured by the fact that the ashes contained potash, and much of the credit of any good effect was attributed to that fact. It has been generally known, however, that lime in peculiarly effective form is in wood ashes, and the favor in which ashes have been held rested not a little upon the curious preference for an organic source of all soil amendments. This is seen in the case of direct fertilizers.

Dealers' Interests. The doubts regarding the wisdom of selecting any one form of lime for the betterment of soil conditions have been promoted very naturally by the conflicting interests of men who would furnish the supply. Some dealers in fresh burned lime have asserted that it was folly to expect any appreciable result from the use of unburned limestone. The manufacturer of ground limestone has pointed out the possibility of injuring a soil by the use of caustic lime, and oftentimes has so emphasized his point that farmers have become unwilling to apply fresh or water-slaked lime to their land. Manufacturers of hydrated lime in some instances have made a confused situation worse by insisting upon the claim that there was a fertilizing quality in their goods. Some dealers in lime marls have been unwilling to have the value of their goods rated according to the content of carbonate of lime, and have emphasized the value of fine division of the particles and the absence of any caustic properties. The presence of shells, evidencing an organic source of the material, has helped in the appeal to buyers.

The rightful place of magnesia, and the possible danger of injury from its use, have been a fruitful cause of perplexity, making price per ton only a secondary consideration to the man wanting to supply his soil's needs.

Scientists' Failure to Agree. It is only fair to say that much of the doubt and indecision on the part of the public is directly attributable to the conflicting statements of our scientists. It should be borne in mind that careful investigation in respect to the relative values of the various forms and sources of lime has been confined largely to the short period of time that has elapsed since recognition of the lime deficiency of our country's soils. Our agricultural literature contained little about soil acidity 20 years ago, and our experiment station tests afford only relatively recent results. Some knowledge of sour soils and the efficacy of lime in their amendment is nearly as old as the history of agriculture, it is true, but answers to the questions uppermost in the minds of men wanting to apply lime to land have been sought only within recent years. The variation in soil types, and in sources of lime, and in preconceived ideas of men drawing conclusions from incomplete data may easily account for failure of our soil scientists to be in the close agreement in statement that would remove all confusion in the public mind. However, the agreement respecting the facts is becoming better assured with every added year of investigation, as a study of station bulletins shows.