134 ALFALFA FARMING IN AMERICA. 



and soil subjects. No pretensions are made to special qualifica- 

 tions in this line, but none the less the writer is firmly convinced 

 that more than soil chemistry, as it has been applied for a 

 century, and more than soil physics, as so ably enlarged within 

 two decades, is needed to furnish the explanation of the vital 

 changes of the soil and their relation to successful agriculture. 



When the line between calcareous or limestone outcrop and 

 sandstone outcrop marks as it does the line betw,een profitable 

 land and unprofitable land for certain crop purposes, as it seems 

 to do in some portions of Ohio, it may not be wholly heretical to 

 look to the calcareous compounds as offering at least a part of 

 the explanation of the differences. When history adds the weight 

 of evidence in the maintained fertility of particular calcareous 

 soils the same question is again raised. And since the soil chem- 

 ist and soil physicist have not marked out the differences either 

 in kind or degree, an appeal to the soil biologist, to the soil 

 bacteriologist should now be made. Chester of the Delaware sec- 

 tion once made determinations of the number of bacteria in a 

 gram of a certain Delaware soil before and at periods of a 

 few weeks after this soil had been treated to dressings of lime 

 of various amounts and to Thomas slag. These were all_ 

 in pots in comparison with untreated soil from the same source. 

 The acidity of the original soil was determined and the amount 

 of correction afforded by the treatment was also determined by 

 the same method; while the untreated soil maintained an almost 

 uniform bacterial fioral of about 520,000 bacteria per gram of 

 soil, the soil treated to dressings of lime showea only a partial 

 correction of apparent acidity, but an enormous increase in the 

 number of bacteria per gram of soil. With smaller amounts of 

 lime, say at the rate of 1,000 pounds per acre, the number of 

 bacteria reached 2 to 3,000,000 per gram while with 4,000 pounds 

 of lime dressing per acre, the number of bacteria reach 5 to 

 8,000,000 per gram of soil. If nothing more may be said, we cer- 

 tainly conclude that these results are very suggestive. I wonder 

 if we have really begun the study of the problem of applying 

 lime to siliceous soils? 



Basic Slag a Source of Lime. — Tliere is a phos- 

 pliatic fertilizer on the market in eastern states 

 wherever convenient to ocean ports that combines 

 very nicely available phosphorus and lime. That is 

 the Thomas phosphate or basic slag meal. This 

 stutf is a by-product of the steel mills of England 



