1917] SOILS FERTILIZERS. 121 



dairy cake and meal, linseed cake, dried grains, soy-bean cake and meal, and 

 oats. The first year the net manurial value for all the farms equaled 0.33d. 

 (0.66 ct.) per gallon of milk produced. In the second year the net manurial 

 value was 0.36d. (0.72 ct.) per gallon of milk produced. The range of net 

 manurial values per gallon of milk was from zero to 0.83d (1.66 cts.). 



"A comparison of the results from the groups of farms shows that the meth- 

 ods of management of the liquid and solid manure is one cause of variation in 

 the results from the individual farms, but at least two other factors must be 

 taken into account. These are (1) the quantity of cakes and meals used, and 

 (2) the variation in manurial value of individual cakes and meals." 



A plan for testing' efficiencies of fertilizers, P. L. Gile and J. O. Cakrero 

 (Jour. Amer. Soc. Ayron., 8 {1916), No. 4, pp. 247-255, fig. i).— In a further 

 contribution to the subject (E. S. R., 81, p. 28), " it is proposed that tests of the 

 efficiencies of different fertilizers furnishing the same element shall include 

 applications of three to five different quantities of the standard fertilizer, and 

 that from the data of the tests so planned the efficiencies be calculated on the 

 basis of the relative quantities of the different fertilizers required to produce 

 the same increased yields. It is pointed out that the usual method of conduct- 

 ing such tests and the usual method of calculating efficiencies may be subject 

 to some error, as they are based on an assumption concerning the law of mini- 

 mum, namely, that the curve of increased growth with increasing amounts of 

 the fertilizer in minimum will be a straight line. This assumption is some- 

 times false, as the curve may take a variety of forms. . . . 



" [The pi'oposed method J being based on no assumption concerning the law of 

 minimum, an accurate comparison is possible irrespective of how the yield in- 

 creases with increasing amounts of the fertilizer in minimum. The form of the 

 curve, plotted from the increased yields produced by increasing amounts of the 

 standard fertilizer, shows when a calculation of relative efficiencies is allow- 

 able, and gives some idea of the accuracy of the comparison. As the proposed 

 method involves the idea of always comparing yields of approximately equal 

 magnitudes, an analysis of the crop and determination of dry matter ai'e not so 

 important as in the old method. This principle of the propo.setl method is of 

 particular value for vegetative tests in pots where large and small yields are 

 subject to somewhat different conditions in respect to ratio between soil and 

 root volume and total amount of mineral matter supplied in the water." 



[Fertilizer experiments], E. F. Gasklll {Mnssachusctts Sta. Rpt. 1915, pf. 1, 

 pp. 37a-44(f).- — The results of the twenty-sixth year of an experiment with 

 clover and grass on the relative value of barnyard manure, sodium nitrate, am- 

 monium sulphate, and dried blood as sources of nitrogen are reported, together 

 with a summary of the whole period. " On the basis of 100 for nitrate of soda, 

 the relative standing of the different nitrogen plats and no-nitrogen plats, as 

 measured by total yield during the season, was as follows : Dried blood, 102.46 ; 

 no nitrogen, 99.61; sulphate of ammonia, 99.48; and manure, 99.1; [and] for the 

 26 years, nitrate of soda, 100 ; manure, 76.47 ; dried blood, 75.83 ; and sulphate 

 of ammonia, 57.93. Considering the relative standing of the different nitrogen 

 fertilizers on the basis of yields per aci*e with a mixed crop of clover and grass 

 there is very little difference between the different materials, and the no-nitrogen 

 plats gave yields about as large as those receiving nitrogen." 



Experiments with asparagus, blackberries, raspberries, currants, rhubarb, 

 potatoes, mangels, and alfalfa on the relative value of potassium sulphate and 

 chlorid as sources of potash gave, except in the case of asparagus, results in 

 agreement with those of previous years. " Considering the different crops 

 grown during the 23 years of the experiment, the muriate has proved the better 



