1917] SOILS FERTILIZERS. 125 



with .?oil of commercial liiiio miiterials is of a higli order. From data obtained 

 for a silt loam soil quite deficient in basic material and receiving different 

 amounts of ground limestone under normal conditions, it can be considered 

 that under similar conditions 70 per cent of the calcium supplied by a mod- 

 erate application of limestone — say 2 tons per acre — will have left the car- 

 bonate form within a year. From heavy applications — 6 to 13 tons per acre — 

 the percentage of calcium and magnesium combining with the soil and the pro- 

 portion carried downward and lost are less when referred to the total amount 

 applied, but, expressed as pounds per acre, the quantities are really greater 

 than those from smaller applications. . . . 



" With regard to the elfect of fertilizer treatment upon carbonates residual 

 from applications, it was found that ammonium sulphate was capable of accel- 

 erating the decomposition of carbonates, and is the only fertilizer in common 

 use the effects of which in this direction are unmistakably apparent. In dis- 

 tinction from ammonium sulphate, a physiologically acid salt, sodium nitrate, 

 a physiologically alkaline salt, appears to have a general tendency toward the 

 conservation of carbonates." 



Manure appeared to exert an influence toward the conservation of carbo- 

 nates. <Jf the bases added and not accounted for by the presence of carbonate.s, 

 a considerable proportion was retained by the first 12 in. of soil. The unfer- 

 tilized plats retained much less than the average of the fertilized. The differ- 

 ences in amounts of bases retained in forms other than carbonate by the fer- 

 tilized plats were not great. The soil of the lime extension plats to which 

 were applied 6 and 13 tons of limestone per acre with and without manure 

 retained more calcium and magnesium in the first 12 in. than the soils from 

 five-year rotation plats, although not by any means a proportionate amount. 

 The bases retained were mainly in the first 8 in., but increases were apparent 

 as deep as the samples were taken (24 in.). Tlae manure appeared to have 

 caused increased fixation of calcium by the soil and to have had a tendency 

 toward equalizing its distribution in the several depths sampled. Leaching 

 was the most important source of loss of carbonates and basic calcium. 



Very coarse limestone (1/3 to ]/20 in.) is probably of little value unless 

 applied in excessive amounts. In general, dolomitic stone ground to different 

 degrees of fineness and applied to the soil suffered a less degree of decomposi- 

 tion than corresponding applications of a higher calcium stone. Crop yields 

 from small plats gave no consistent indications of superiority for either form 

 of stone. Soils containing water-soluble acid constituents in determinable 

 quantity were rarely encountered. 



" The litmus paper test, when carefully conducted and intelligently inter- 

 preted, is probably as good as any chemical test for the determination of the 

 soil's need of lime. All the lime requirement methods tried indicated marked 

 differences between limed and unlimed soil of the same character and treat- 

 ment, and all, except the Veitch method, loss in bases due to a long period of 

 cultivation. 



" The data available indicate that the vacuum method is the best adapted 

 of the procedures tested for use as a quantitative method in studying the rela- 

 tions between the soil and its supply of bases. There is no evidence that any 

 of the lime requirement methods tested furnishes reliable indications as to the 

 optimum rate of application for field practice. For the several soils inves- 

 tigated, there was found to be an approximately quantitative relationship be- 

 tween the bases soluble in fifth-normal nitric acid (excluding carbonates) and 

 differences in lime requirement by the vacuum method. 



"Acidity of soil, as the term is usually employed, is a negative property ; 

 that is, due to qualities inherent in all soils, but manifested only by those 



