SOILS FERTILIZERS. 721 



Annual review of agronomy, I). Zolla (Rev. Gen. ScL, 19 (IDOS), Xo. l), 

 pp. 577-.5S5). — This article rovlows new theories of soil fertility, particularly 

 those advanced by the Bureau of Soils of this Department, and experiments on 

 the use of manganese as a fertilizer, on the permeability of soils as I'elated to 

 irrigation, and on the utilization of alkali soils for the culture of rice in La 

 Camargue. 



Experiments on the decomposition and fertilizing value of manure, R. 

 Sjoli.kma and J. C. dk Ruijtkk ue Wildt (VcrKhiy. Landboinrk. Ondcrzock. 

 RijksihuKlhoincprocf.stat. [Xetherlands!], 1907, Xo. 1, pp. 21-6S, figs. 2; ahs. in 

 Zciithl. -Ir/r. Vhciti., 37 (1908), No. 10, pp. 652-654)- — A series of studies of the 

 fermentation and tests of the fertilizing value of manure, in comparison with 

 other nitrogenous fertilizers, in continuation of previous investigations (E. S. II., 

 18, p. 325), are reported. 



The experiments on decomposition were made with 2 kg. lots of fresh cattle 

 manure treated in different ways for 2 months. The manure fi-om these 

 experiments as well as fresh manure was used in comparison with nitrate of 

 soda and sulvhate of ammonia on oats followed by rape grown in cylinders. 

 The results show that an important loss of free nitrogen may take place in 

 manure, the loss depending, in addition to length of fermentation and tempera- 

 ture, largely upon the amount of exposure to the air. At room temperature 

 the loss is much smaller than at a temperature of 3.5 to 37° C, and ceases at 

 about 50°. The exact cause of the loss was not determined in the exi)erimeuts, 

 but appeared to be due to oxidation of ammonia by micro-organisms. With 

 protection from the air no loss of nitrogen occurred either in the form of free 

 nitrogen or of ammonia, not even with a very vigorous gas formation (methane 

 and carbon dioxid) lasting several months. AVith fermentation under aerobic 

 conditions combustion of organic material apparently occurred whereby oxygen 

 was partly taken up by other compounds of the manure, or decomposition took 

 place whereby carbon dioxid was formed without absorption of oxygen. Both 

 with protection from and exposure to the air the furfurol-producing substances 

 in manure were attacked, and more violently than the other constituents of the 

 manure. 



The cylinder experiments showed that the ammonia content of the manure is 

 not always a correct measure of the fertilizer effect. The composition of the 

 nitrogen compounds can not be taken exclusively, since the more or less fer- 

 mented state of the nitrogen-free constituents must also plaj' a large part. 

 The nitrogen in those kinds of manure in which the furfurol-producing con- 

 stituents were most fermented had the best effect. This is attributed to 

 destruction of the food for denitrifying organisms. Anaerobic fermentation at 

 higher temjK'rature increased decidedly the direct fertilizing value of stable 

 nmnure, since witli a violent fermentation of th(> organic material and decoi.i- 

 position of furfurol-producing constituents, vigorous formation of anunonia 

 takes jtlace, and no loss of nitrogen either as ammonia or in a free state need 

 be feared. Of manure in which favorable decomposition has taken place about 

 one-third of the nitrogen can be taken up by the plant roots within a single 

 montli, so that the ratio of availability of this nitrogen to that of nitrate of 

 soda is about 50:100. Fresh manure shows in the .same year a greater after- 

 effect than oii(. subjected to fermentation, but this is not enough to conii>ensate 

 for the smaller increase of the first crop. The after-effect of stable manure 

 which has fermented at various temperatures under aerobic and anaerobic 

 conditions is slight in the same year, and the experiments reported show no 

 noteworthy ditTcrence in the amount of this after-effect. 



