130 Report of Farmers' Institutes 



PREFACE TO PROF. McINTYRE'S ARTICLE 



Through a misunderstanding, Professor Mclntyre prepared a 

 paper which follows, on "' The Use of Lime," but did not present 

 a concise statement as to the relative value of fineness in carbo- 

 nate of lime, as outlined by the program. 



After consultation with Dr. L. L. Van Slyke, of Geneva, and 

 Professors E. O. Fippin and George W, Cavanaugh, of Cornell, 

 the statements on this subject given at the last year's Normal were 

 reiterated, and is as follows : 



LIME 



Professor E. O. Fippin 



status of knowledge 



Our knowledge concerning the nature of soil acidity and the 

 effects of lime, together with the relative efficiency of different 

 forms of lime in the soil and their effects on the various factors 

 that determine fertility of the soil, is still very incomplete. 

 Similarly, our knowledge as to the exact relation of different 

 varieties of crops and field plants to soil acidity and lime is very 

 incomplete. Information of this sort is accumulated very slowly 

 and it is important that we retain an open mind for new data. 



NATURE OF SOIL ACIDITY 



Definitions of soil acidity are difficult to frame and are largely 

 unsatisfactory. Two classes of material in the soil may give rise 

 to acidity. These are the inorganic or mineral acids and the 

 organic acids resulting from the decay of organic matter. The 

 earlier notion that organic acids are relatively few in number 

 and simple in composition and relationship is now thoroughly 

 displaced. A large number of organic acids in the pieces of plants, 

 and also resulting from the decay of organic matter in the soil, 

 are now known. They vary with the soil and the plant. That 

 definite free acids occur in the pieces of plants used as green 

 manure is shown by a recent study of covill, of the U. S. De- 

 partment of Agriculture : 



Yield per Lime Free acidity expressed 



Crop acre content as lime requirement 



Alfalfa 21/2 tons 193 lbs. 267 lbs. 



Red clover 2 tons 131 lbs. 142 lbs. 



Cow pea 2% tons 92 lbs. 200 lbs. 



Rye 2 tons 1 1 lbs. 178 lbs. 



Broom sedge 1 ton 4 fca. 89 lbs. 



