January 7, 1916] 



SCIENCE 



31 



dried blood in soil from fertilizer plata of an 

 experiment that has been in progress for eight 

 years. In some cases the use of one per cent, 

 dried blood resulted in no nitrification at all 

 in four weeks' incubation, but rather a partial 

 loss of the nitrates originally present. In soil 

 from other plats, however, vigorous nitrifica- 

 tion took place. The soil throughout these 

 plats has been derived from disintegrated 

 granite and is quite sandy and very low in 

 organic matter and nitrogen. In view of the 

 extensive use now being made of dried blood, 

 and the scientific interest attached to the sub- 

 ject, an extended study of nitrification in 

 Southern California soils has been undertaken. 

 Such questions as the relative rates of nitrifi- 

 cation of dried blood, bone meal, ammonium 

 sulfate, etc., the effects of lime, the influence 

 of organic matter and other factors are being 

 studied. The investigations are still in prog- 

 ress. Certain of the results already obtained, 

 however, seem of sufficient interest to war- 

 rant preliminary discussion at the present 

 time. Later, a more complete presentation of 

 the investigation will be submitted. 



At the outset it was found that vigorous 

 ammonification of different organic fertilizers 

 took place in all plats studied and that the 

 addition of lime did not greatly affect either 

 ammonification or nitrification. When the 

 conventional amount of nitrogenous materials 

 was added, however, dried blood was not nitri- 

 fied in soil from certain plats, while bone meal 

 and ammonium sulfate underwent vigorous 

 nitrification. In soil from other plats no such 

 difference was observed. The following re- 

 sults illustrate the difference in nitrification 

 in two plats. 100 gm. of soil in duplicate was 

 employed in each case. 



Increase In Nitric. N. p. p. m. 

 Plot B, Plot U, Manure. 

 Rock Plios. 

 Materials Added Unfertilized and Legume 



1 gm. dried blood — 2.8 170 



1 gm. bone meal 92.8 154 



0.15 gm. ammoniuua sulfate. 67.8 136 



Similar observations have been reported 

 from other soils of California.^ 



2 Lipman and Burgess, Calif. Sta. Bull. 251 and 

 260, 1915. 



It is of interest in this connection that cer- 

 tain plats in the field experiments, from which 

 the above soils were drawn, have been fertil- 

 ized annually for eight years with dried blood 

 only, and that marked stimulation has resulted 

 in the growth and vigor of the citrus trees, on 

 the one hand, and in the yield of fruit, on the 

 other. For example, the yield during the past 

 two years has been increased more than 100 

 per cent, by the use of dried blood. Further- 

 more, a material increase in the nitrate con- 

 tent of the soil is foimd at the present time 

 wherever dried blood has been applied, indi- 

 cating that this material undergoes nitrifica- 

 tion in the field. 



Two questions, therefore, present them- 

 selves. First, why should dried blood fail to 

 undergo nitrification in soil from certain plats 

 but be nitrified vigorously in others, while at 

 the same time bone meal and ammonium sul- 

 fate are capable of being vigorously nitrified in 

 each? This question seems especially per- 

 tinent since ammonification, generally con- 

 sidered to be essential as preliminary to the 

 nitrification of organic substances, takes place 

 actively. Second, why does dried blood 

 undergo nitrification in the field but not in 

 the laboratory? 



Entirely satisfactory answers to these ques- 

 tions can not now be given. Some light has 

 been thrown on them, however, as will appear 

 from the discussion below. 



While the proportion of dried blood to soil 

 employed in the above experiments was the 

 same as is commonly used in laboratory ex- 

 periments on nitrification, nevertheless, the 

 possibility that excessive concentrations of 

 dried blood had been employed was at once 

 suggested. In the field experiments an annual 

 application of 1,080 lbs. of dried blood per 

 acre is now being made to certain plats, ap- 

 plied in approximately equal applications in 

 February, April and July. The addition of 

 1 gm. per 100 gm. of soil, on the other hand, 

 corresponds to an application of 15,000 lbs. per 

 acre, estimating an acre foot at 3,000,000 lbs. 

 and reckoning that the field application be- 

 comes incorporated with the soil to a depth of 

 six inches. Accordingly, a series of laboratory 



