426 EXPERIMENT STATION BECOED. [Vol.37 



reported in which it was found "that the dried sludge has a market value upon 

 present figures of $9 to $15 per ton of material containing 10 per cent moisture. 

 The total cost of getting this product and placing it on the market will probably 

 run from $8 to $12 commercially per dry ton, depending upon local conditions. 

 For large plants this cost may possibly be reduced as a result of further 

 experience. 



"The activated sludge containing 4 per cent or more of nitrogen is much 

 nearer a commercial possibility than the sludges obtained by the older methods 

 of treatment, such as chemical precipitation, septic tanks, or the ImhofE pro- 

 cess, which . . . contain only 1.5 to 3 per cent of nitrogen." The data indi- 

 cate "that the recovery of the nitrogen in sewage sludge has at last been 

 brought within the range of a commercially practicable problem." 



Report on humogen, E. J. Russell (Jour. Bd. Agr. [London], 24 (1917), 

 No. 1, pp. 11-20). — Reviewing fully the experimental work which has been 

 done on the subject, the author finds " no evidence that humogen possesses any 

 special agricultural value. There is not the least indication that it is ' 50 times 

 as effective as farmyard manure," to quote an often repeated statement, and 

 there is nothing to show that it is any better than any other organic manure 

 with the same content of nitrogen. It is offered at present at £5 per ton in 

 2-ton lots; . . . [the Rothamsted] experiments give no reason for supposing 

 that it is worth anything like so much." 



The investigations have shown wide variations in the composition of the 

 material, as well as in the results of tests of its fertilizing value. The author 

 states that " there is no definite evidence that ' bacterizatlon ' really adds to 

 the value of peat." 



Further careful experimental work on tlie subject is recommended. 



Grape cake as a fertilizer. L. Roos (Prog. Agr. et Vit. (Ed. VEst-Centrc), 

 57 (1916). No. 46, pp. 463-46S). — It is stated that grape cake contains on the 

 average 1 per cent of nitrogen, 0.5 per cent of potassium, 0.5 per cent of 

 phosphoric acid, and 35 per cent of organic matter. Its fertilizing value is 

 considered to be double that of barnyard manure. 



Information on its use as a fertilizer is also given. 



Comparison of four nitrogenous materials as sources of nitrogen, Z. 

 BoNOMi and G. Mabgbeth (/?. Lab. Chim. Agr. Udinc, Ric. Spcr. c Aitiv. 

 Spiegata, 4 (1911-1914), pp. 29-34). — Comparative tests with grain, on a soil 

 low in nitrogen and organic matter, of calcium nitrate, sodium nitrate, am- 

 monium sulphate, and calcium cyanamid are reported. In the order named the 

 fertilizers are applied at rates of 8.57, 6, 4.5, and 6 kg. per hectare (7.62, 5.34, 

 4, and 5.34 lbs. per acre). 



In grain production, the best results were obtained with calcium nitrate, 

 followed in order by sodium nitrate, ammonium sulphate, and calcium cyan- 

 amid. In straw production, calcium nitrate showed the best results, followed 

 In order by ammonium sulphate, sodium nitrate, and calcium cyanamid. Con- 

 sidering the value of the results obtained with calcium nitrate as 100, sodium 

 nitrate, ammonium sulphate, and calcium cyanamid stood, respectively, as 42, 

 37, and 31. 



The action of superphosphate in tests in 1913, J. M. Geerts (ilcded. 

 Proefstat. Java-Suikcrindu^., 6 (1916), No. 19, pp. 543-651, figs. 7; Arch. Suiker- 

 indtis. Nederland. Indie, 24 (1916), No. 52, pp. 2065-2173, figs. 7).— This is an 

 extensive report of fertilizer experiments with double superphosphate on cane 

 soils. 



It was found that double superphosphate had a distinct action on cane soils 

 poor In phosphoric acid, but in soils rich in phosphoric acid no effect was 



