75 



of a rain, these salts arc largely washed down into the 

 deeper layers of the soil, to be again returned to the 

 surface, with the return of dry weather. In labora- 

 tory work, where the water content is kei)t nearly con- 

 stant, there is little chance for this niovenieni of the 

 salt into zones, and hence, retarded, or even inhibited 

 nitrification results. 



While the data given in Tables IX and X show that in- 

 cubating acid soils with either dried blood or sulphate 

 of annnonia tends to bring manganese into solution, it 

 sould be remembered that our soils contained initially, 

 but little soluble manganese. It is not surprising, 

 therefore, that dried blood was nitrified to a considera- 

 ble extent. On the other hand, several of the soils 

 used failed to nitrify ammonium sulphate. It is prob- 

 able that manganese brought into solution by this com- 

 pound, acted as the agent inhibitory to nitrification. 



To make a practical application, our work indicates 

 that unfertilized acid soils supporting a slow rale of ni- 

 trification, develop but little soluble manganese. On 

 the other hand, if such soils be liberally fertilized with 

 nitrogenous fertilizers, the acids produced therefrom 

 may bring into solution sufficient quantities of manga- 

 nese to cause serious injury to crop plants. The use 

 of lime in connection with high fertilization becomes 

 imperative, then, if full benefit is to be derived from 

 such fertilization. Whether or not plowing under of 

 large crops of leguminous plants would produce results 

 similar to those obtained with certain fertilizers, is a 

 point that cannot be answered at present. 



Summary 



1. Acid soil on the Alabama Experiment Station 

 Farm has been shown to l)e injured by the use of dried 

 blood as a fertilizer. It is indicated that cotton seed 

 meal may also cause injury in time; as yet, little injury 

 has resulted from its use. 



2. In pot experiments, dried blood and ammonium 

 sulphate produced almost complete sterility in two dif- 

 ferent soils from the Experiment Station Farm. Lime 

 added to these soils not only prevented injury, but pro- 

 moted a very vigorous plant growth. 



3. Soil which has been made highly unproductive 

 by heavy applications of dried blood, still supports ni- 

 trification under field conditions, 



4. The infertility of this soil is attributed to the pres- 



