SOILS FERTILIZERS. 523 



fertilizing materials examined during tlie year. For ttie first time " ttie analyses 

 of mixed fertilizers include deterniinations of the solubility of the organic 

 nitrogen both in water and in an alkaline solution of ix>tassium permanga- 

 nate." The results are stated as (1) water-soluble organic nitrogen, (2) active 

 insoluble organic nitrogen, and (3) inactive insoluble organic nitrogen. The 

 reasons for this are stated as follows : " Organic nitrogen costs four or five 

 times as much as phosphoric acid or potash, and the forms in which it is used 

 in mixed fertilizers differ greatly in market price as well as in agricultural 

 value. Some method for distinguishing the forms which have real agricultural 

 value from those which are comparatively inert is most desirable, and after 

 several years of study and experiment both here and elsewhere methods have 

 been devised to determine the solubility of organic nitrogen and thus to dis- 

 tinguish between the two forms of nitrogen with enough accuracy to make 

 their use helpful in judging of the quality of organic nitrogen." 



Experimental work on the availability of organic nitrogenous fertilizers at 

 the Connecticut Station is presented in 3 papers by J. P. Street as follows : 



A modification of the neutral pennanganate metJiod to determine the solu- 

 bility of organic nitrogen (pp. 9-11). — It was found that the method originally 

 proposed by the author (E. S. B... 23, p. 706) gave misleading results when used 

 with certain mixtures of acid phosphate and organic nitrogen, but this difficulty 

 was overcome and satisfactory results were obtained by adding 1 gm. of sodium 

 carbonate just before the permanganate solution was introduced. 



SoluMlity of organic nitrogen of raw inaterials by the alkaline permanganate 

 method (pp. 12-14). — Results of tests of 55 samples of fertilizer materials by 

 this method are reported and compared with results of tests by the neutral 

 permanganate method with dried blood, tankage, dried fish, and castor pomace. 

 The neutral permanganate method gave decidedly higher results than the alka- 

 line permanganate method. " There is no question that either method serves 

 as a useful means of distinguishing between such materials as blood, bone, 

 tankage, and fish on the one hand, and materials like peat and leather on the 

 other. ... In a valuable material, such as castor pomace, the alkaline method 

 shows an average solubility of 48.2, classing it, if judged by this figure alone, 

 with the inferior materials. The neutral method gives castor pomace a solu- 

 bility of 88. close to that obtained with other high-grade materials. In such 

 instances as this, if tlie alkaline method is to be used with any certainty, strict 

 attention must also be given to the amount of water-soluble organic nitrogen." 

 which averages 78 per cent in castor pomace but is present only in traces in 

 peat. 



Pot experiments on nitrogen availability (pp. 14-23). — The main object of 

 these experiments was to compare hair tankage, garbage tankage, and treated 

 leather used in the " wet mixing " process of fertilizer manufacture, which is 

 described, with such materials as sodium nitrate, cotton-seed meal, and peat. 

 The tests were made in ordinary 8-in. flower pots containing 13 lbs. of mixed 

 soil (7 parts sand and 1 part garden soil) to which was added a basal fertilizer 

 of 1.5 gm. of potassium sulphate, 4 gm. of acid phosphate, and 2 gm. of calcium 

 carbonate. The nitrogenous fertilizers were as a rule applied at rates supply- 

 ing 0.15 gm. of nitrogen per pot. Millet and oats were the crops grown. The 

 results measured in crop yield and nitrogen recovery " indicate that the ' wet- 

 mix ' acid treatment of materials, like hair waste, treated leather, and garbage 

 tankage, yields a fertilizer of high crop-producing power with millet and oats, 

 and one whose nitrogen availability to these crops is superior to that of cotton- 

 seed meal, and from 60 to 75 per cent of that of nitrate of soda. Furthermore, 

 in these tests the value of the base-goods nitrogen rested almost entirely on the 

 35693°— Xo. 6—12 3 



