464 



STATE BOARD OF AGRICULTURE. 



dissolved. The 0,2 g, of KH0PO4 dissolved in 50 cc. of liquid make a 

 solution of 0.4%. The same amount in 50 g. of sand with 20% mois- 

 ture, i. e. with 10 g, of HjO makes a 2% solution. The acidity of this 

 latter solution, 5 times as high as in the furmer, may possibly re- 

 tard the g^o^\•th while a 0.4% solution is useful by furnishing valu- 

 able food. With this supposition agrees the circumstance that in Series 

 V, the average increase due to the minerals is only 0,2 cc. at 15% 

 moisture, while at 25% moisture the minerals being more diluted, the 

 increase is 1.5 cc. In the soils, the acidity is jn'obably neutralized 

 by the lime of the soil, and the minerals prove helpful in every case, 

 though the degree varies with the soils. Table V gives the average in- 

 crease of the fertilized cultui'es over the corresponding unfertilized 

 samples. 



TABLE V. 

 Increase of Ammonia Due to Mineral Salts. 



The two unproductive soils, the subsoil and Soil B, react very prompt- 

 ly upon the fertilizer, while the surface soil. Soil A and the i>eat 

 show a much smaller increase, about l.G cc. in the average against 

 3,0 cc. in the unproductive soils. In the soils as well as in the liquid 

 cultures, the effect of fertilizers increases with the age of the culture 

 to such an extent that the increase is at least proportionate with the 

 increase of total ammonia. 



The Same Data on the Basis of Sail Solution. — In all previous dis- 

 cussions, the ammonia has been computed on the basis of 50 g. dry soil 

 or 50 cc. of solution resj)ectively. This melhod is (piite customary in 

 soil bacteriology and it has been used in the first pages of this i)aper 

 purposely to show that it is absolutely impossible for bacteriological 

 experiments. It may be proper to say that Soil A produces 15 cc n/10 

 NH3, and it produces more at 25% moisture than at 20%. But if one 

 were to conclude from that, that the bacteria thrive better at 25%> 

 than at 20% moisture, one would make a serious error. If one com- 

 I>ares bacterial activity, there is only one basis i)ermissab1e, namely 

 equal amounts of medium. The medium is the soil solution only, not 

 the undissolved soil i)articles, and a comparison must be based uiion 

 equal volumes of soil solution. To compare 100 g. of soil with 10% 

 moisture and 100 g. of the soil with 20%. moisture would l)e just as 

 unreasonable as to com])are the amount of acid formed in 10 cc. of 

 one milk and in 20 cc. of another. How much reason the soil chemist 

 might have for figuring his analysis per 100 g, of dry soil, the soil 

 bacteriologist can not possibly follow this procedure if he wants to 

 know anything about bacterial develojnnent in the soil. 



