14 

 (190 samples); between 4 and 5 per cent (315 samples); and 5 per cent or over (228 

 samples). 



Fig. 1. — Proportion of Mineral and Organic Nitrogen Found. 



'\////Wm///m/m ^\ ^r ^? ^1^ '^\ ^ ^? ^'l " A™»0'»ia Guarantee 



Below 2 



2 to 3 



3 to 4 



4 to 5 



5 or over 

 The shaded portion indicates mineral, the unshaded portion organic, in 100 parts of nitrogen. 



The above graph shows that as the ammonia guarantee is increased, the proportion 

 of mineral nitrogen is increased, so that in those brands having an ammonia guarantee 

 between 4 and 5, over one-half is in the form of nitrates or anunoniates. The data 

 presented above raise the question of the economy of supplying such a large propor- 

 tion of organic nitrogen in those brands having a low ammonia guarantee. These 

 goods are probably used chiefly as a supplement to the manure supply of tlie farm. 

 Since the nitrogen in manure is relatively slow acting, it follows that it should be 

 supplemented by quick acting rather than by further applications of slow acting 

 nitrogen. 



Fig. 2. — Percentage of Total Nitrogen in Active Form. 



Based on the alkaline permanganate method and the assumption that all of the water soluble nitrogen 



is active. 



100 Amnonia Guarantee 



Below 2 



2 to 3 



3 to 4 



4 to 5 



5 or over 

 The shaded portion represents active, the unshaded portion inactive, nitrogen. 



The above graph indicates a surprisingly slight difference in the activity of the total 

 nitrogen in the various grades. The use of an increased proportion of mineral nitrogen 

 is probably responsible for the slightly increased activity in the nitrogen of the high 

 ammonia grades. g-^ 



Active versus Inactive Organic Nitrogen. 

 Fig. 3. — Percentage of Total Organic Nitrogen in Active Form. 



10 20 30 40 50 60 70 80 90 100 Ananonia Guarantee 



Below 2 



2 to 3 



3 to 4 



4 to 5 



5 or over 



Fig. 4. — Percentage of Water Insoluble Nitrogen in Active Form. 

 30 40 50 60 VO 80 90 10 Ammonia Guarantee 



Below 2 



2 to 3 



3 to 4 



4 to 5 



5 or over 



The shaded portion represents active, the unshaded portion inactive, organic nitrogen by the alkaline per- 

 manganate method. In Figure 3, the active organic nitrogen includes the water soluble and the active 

 water insoluble forms. 



