FERTILIZERS. 873 



111 experimeuts in which hue soil alone or coiiihincd witii cailjoiiate 

 of liuic, '■'i)recii)itate,'' kaiiiit, and gypsum were used as preservatives 

 and air admitted, iiitrogeu in the form of ammonia, nitrous acid, and 

 nitric acid were not found in the samples either at the beginning or 

 end of the experimental jieriod except where soil, calcium ciirbonate, and 

 "precipitate" were used, when a trace of nitric nitrogen was detected. 

 None of the preservatives prevented the formation of free nitrogen to 

 any marked extent, although gypsum was somewhat more ettective in 

 this respect than the other preservatives. 



These experiments in general showed that the loss of nitrogen from 

 both dung and litter and from urine and litter m;iy be prevented by 

 excluding- the air. Where air had access, chemical preservatives, with 

 the exception of "precipitate" and double superphosphate, in case of 

 mixtures of solid excrement and litter were effective in preventing a loss 

 of nitrogen. The production of ammonia in solid excrement is almost 

 insigfuificant, while the nitrogen of urine is almost comjjletely converted 

 into ammonia. In view of this fact, it is suggested that it might be 

 advisable to carefully separate the urine from the other manure and 

 store it in receptacles from which the air is excluded. 



Experiments are in progress to determine the losses from manure 

 after it has been applied to the soil. 



The fertilizing value and the preservation of nitrogen of barn- 

 yard manure, 'I. Aeby, U. Doksch, F. Matz, and I'. WA(;neii 

 [Ldndw. Vers. Stat., 48 (1897), Nos. 3-5, pp. 247-360, chjms. 2).—X detailed 

 rejjort is given of pot experiments during several years to test the rel- 

 ative value of the nitrogen in commercial fertilizers and in the solid 

 and liquid excrement of animals, as well as the inlluence of various 

 preservatives ujion the fertilizing value of manure. The principal con- 

 clusions of this investigation are as follows: 



(1) The nitrogen of manure is decidedly less available than that of 

 ammonium compounds and nitrates or of green plants. 



(2) The nitrogen of solid excrement and of straw acts verj' slowly. 

 It is transformed largely into humus, and changes very slowly into 

 ammonia and nitric acid. 



(3) The nitrogen of urine is transformed very quickly into ammonia, 

 the transformation being complete at ordinary room temperature in 48 

 hours. The addition of solid excrement and straw hastens the process. 



(4) The nitrogen of urine acts very quickly and its assimilability is 

 very nearly the same as that of ammonium comiiounds. 



(5) When a soil is liberally fertilized with fresh solid excrement and 

 immediately seeded with quick-growing plants, the manuring may 

 result in a reduction of yield. This reduction of yield is due to the 

 setting free of elementary nitrogen from the nitrogenous mattei- which 

 is present in the soil, or which has been applied in the more available 

 forms of urine, green manure, ammonium conq)(»unds, or nitrates. This 

 eflect of the solid excrement is attributed to the denitrifying bacteria 



