972 Journal of Agricultural Research vol. vi, No. 24 



The nitrifying capacity averages in the last column of Table X place 

 timothy at the top of the list, manure in this case having no effect. Next 

 in order are wheat and corn, where manure is added. Manure had no 

 increasing effect on the rotated plot. The continuously cropped plots 

 without manure, the rotated plots, and the plots receiving chemicals 

 vary little. Manure here exercises little or no influence on those crops 

 not depleting the soil of organic matter. 



It is evident that the nitrifying floras of plots 9, 17, and 22, the first 

 two especially, were extremely weak. Though these plots possessed 

 at this time good nitrate-forming floras, they were not able to overcome 

 the adverse effects experienced in transferring them to soils slightly less 

 favorable but in which a more vigorous or differently constituted flora 

 thrived. 



NITRATE NITROGEN UNDER FIELD CONDITIONS 



In Table XI is given the quantity of nitrogen as nitrate per 100 gm. of 

 soil when the soil was collected from the field, but nothing particularly 

 marked is to be noted from the results given. As would be expected, 

 this quantity varies considerably; but since the demands made upon the 

 various plots by the growing crop differ widely, little information is 

 furnished regarding the rate of formation. After the wheat is harvested 

 the nitrate content of wheat plots increases rapidly. Wheat was cut 

 on June 20, 1913, and on June 28, 1914. Some accumulation is evident 

 even before harvest. When wheat is growing rapidly no nitrates are 

 present. The accumulation is much more marked in the presence of 

 manure and chemicals than in their absence. There is an abundance 

 of nitrate nitrogen under corn even when it is making its most rapid 

 growth. During 191 3 the water content fell so low in July and August 

 that no nitrates could be formed; with rain coming in October, however, 

 the nitrate content rose rapidly. In all cases where a comparison of the 

 same crop in the presence and absence of manure is possible the nitrate 

 content of the manure plot is materially higher than that of the un- 

 manured. 



