_Use of the Manure Spreader._ The next best device is the manure spreader. The makes on the market vary in ability to do satisfactory work with lime, and none does even work with a small quantity per acre. An addition to the bulk to be handled by placing a layer of other material in the spreader before filling with lime helps, but some spreaders do fair work in spreading as little as 3000 pounds of slaked lime per acre, and certainly far better work than usually is done with shovels from a wagon. CHAPTER XVII AMOUNT OF LIME PER ACRE _Soils Vary in Requirement._ There is always the insistent question respecting the amount of lime that should be used on a particular field. Usually _no_ definite reply can be safely made. The requirement of the present, and probably of the _next_ few years, should be met by one application. The existing degree of acidity is an unknown quantity until a careful test has been made. There are soils so sour that several tons of fresh burned lime per acre would only meet present requirement, and there are soils so soundly alkaline that they need none at all. This uncertainty regarding amount required is responsible for much failure to do anything, even when some acidity is indicated by general appearance. _A Working Basis._ If land has once been productive and in later years clover has ceased to grow and grass sods are thin, there is a strong probability that liming will pay, and the experience of farmers on normal soils, and the tests of experiment stations, justify the estimate that two tons of fine stone, or one and a quarter tons of fresh burned lime per acre, can be used with profit. This amount probably will permit fertilizers and tillage to make their full return in heavy sods that will provide humus. It is a reasonable expectation that the application will serve through a crop rotation of four or five years. If the soil was not very sour, the second application at the end of four or five years may be reduced somewhat, and even a ton of stone given once in the crop rotation may fully meet the requirement. In the case of the normal soil that has ceased to grow clover, and does grow plants that are acid-resistant, it is better practice to secure a relatively low-priced supply of coarsely pulverized stone and apply three or four tons per acre, and thus lengthen the interval between applications to eight or 10 years. The fine material in the heavy application will take care of present need, and the coarser particles will disintegrate later on. The quantities suggested may not be the most economical for the reader, but their use cannot be attended by loss if a soil is sour, and there is reason to believe that it is much better to use such quantities without question than to defer liming for a year in the hope that some more definite knowledge of a particular field's needs may be secured.