FORTY-FIFTH ANNUAL REPORT. 157 



aud untreated soils. Again, if the root development of the plant is in- 

 creased, naturally the amount of phosphorus, etc., taken up by that 

 particular crop will be increased and in many cases the yield also. I 

 should strongly emphasize this point. It is possible that we have not 

 studied sufficiently the changes taking place below the surface of the 

 soil! The last point in this connection is the correcting of soil acidity, 

 we usually apply lime to soil to correct this condition. It seems that 

 we may have other changes taking place at the same time. It is not 

 strange, therefore, that ditferent individuals get different results. We 

 should never lose sight of the fact that soils vary in different localities. 



In order to discuss this matter fully, perhaps we ought to mention 

 the kind of lime compounds. You know they are divided into car- 

 bonates, hj^lrates, and oxides. 



Th-ere are several forms of lime used for agricultural purposes. 

 Those most commonly used are the carbonates, or ground limestone, 

 marl, air-slacked, sugar factory, tannery, and wood ashes, the hj^drate 

 or water and partially air-slacked lime, and less commonly, the caustic, 

 quick, or oxide of lime. 



In using lime we must consider the solubility of these compounds, the 

 requirement of the soil, and the kind of crops we are to grow on the 

 soils. 



The form of lime to use will depend primarily- upon th j cost of appli- 

 cation. In general, two or three parts of finely ground limestone, or 

 marl, are required to do the business of one part of hydrated lime that 

 is immediately. It should be borne in mind, however, that the hydrated 

 lime is somewhat more soluble than the carbonate, but such differences 

 in most cases are accounted for in the above ratio. 



Marl is one of the most valuable forms of lime to use where it is with- 

 in striking distance of the land. It is in a very finely divided state and 

 therefore goes into solution more readily than coarser particles. 



Hydrated lime reacts more vigorously and quickly in the soil ihe 

 first season and precautions should be taken to apply it several days 

 })revious to seeding a crop, inasmuch as it may injure the young seed- 

 lings, especially if it is not thoroughly incor])orated with the soil. 

 It's caustic action or organic matter in the soil has been somewhat 

 over-estimated, but long continued experiments show that it does 

 cause a somewhat more rapid decay of the vegetable matter. Hydrated 

 lime soon changes to the carbonate in the soil and if it is more active 

 after such change than other carbonates, it is due to its fineness of 

 division and thorough mixing with the soil. 



In practice it is generally true that various forms of lime show best 

 results the second year after application. This, however, depends in 

 part upon how thoroughly it is mixed with the soil when applied, 

 by means of a drag or disc. 



ANY LIME COMPOUND SHOULD BE THOROUGHLY INCOR- 

 PORATED IN THE UPPER TWO OR THREE INCHES OF SOIL, 

 ESPECIALLY IN THE CASE OF FINE TEXTURED SOILS. 



I have had a number of inquiries covering the relative value of mag- 

 nesia limestone and ordinary limestone. Magnesia limestones, in gen- 

 eral, are composed of about 45% carbonate of magnesia and about the 



