RECENT WORK INAGRICUETURAL SCIENCE. 



AGRICULTURAL CHEMISTRY— AGROTECHNY. 



Proceedings of the twenty-sixth annual convention of the Association of 

 Official Agricultural Chemists, held at Denver, Colo., August 26-28, 1909, 

 edited by H. AY. Wilf.y (C7. 8. Depi. Agr., Bur. Chcm. Bui. 132, pp. 127, figs. 7).— 

 This is the usual detailed report of the proceedings, extracts from which have 

 been previously noted (E. S. R., 22, p. 614). Papers were also i)reseuted as 

 follows : 



Determination of ammonia hi/ the official magnesium oxid method, T. C. 

 Trescot (p. 20.) — The author believes that the results obtained by distilling 

 with magnesium oxid should not be reported as free ammonia, but should be 

 expressed as ammonia obtained by distillation with magnesium oxid. 



Inter prclation of soil analyses with respect to pliosphoric acid, G. S. Fraps 

 (pp. 33, 34). — The author states that the phosphates of lime and the normal 

 ferrous or ferric and aluminum salts are easily soluble in fifth-normal nitric 

 acid, while the basic salts of iron and aluminum are only sparingly so. From 

 this, however, it must not be concluded that all soils which contain the same 

 amount of phosphates of lime react in the same manner toward phosphoric 

 fertilizers and particularly to plants. _ 



" Reducing it to its lov.-est terms, the analysis of a soil with fifth-normal 

 nitric acid amounts to this: Knowing the quantity of phosphoric acid exti'acted 

 by the solvent, and the absorptive power of the soil for phosphoric acid, esti- 

 mate how much phosphate of lime is present in the soil. Then, knowing the 

 amount of acid consumed, consider to what extent this phosphate is distributed 

 W'ithin the mass of the dissolved material and to what extent it is exposed to 

 the roots of the plants. Having estimated the amount of exposed phosphate of 

 lime, we have next to inquire how much of it is necessary to make a soil fertile. 

 What conditions .iffect the rate and the quantity of phosphoric acid which these 

 phosphates give up? Then the probable value of the basic ferric and aluminum 

 phosphates present must be considered, and whether or not organic phosphates 

 are in the soil. Having considered all these questions, we will be in a positioa' 

 to interpret the analysis of a soil with fifth-normal nitric acid." 



Methods for the determination of the nitrifying and ammonifying poicern 

 of soils, F. L. Stevens and W. A. Withers (pp. 84-38). — The nitrifying indexes; 

 set up by the authors are as follows: Nitrification inoculating power (N. I. P.> 

 has to do with the factor of the live organisms present and does not take into 

 consideration the fitness or nonfitness of a soil for their activity. It also does; 

 not consider species of bacteria but takes them as a whole. Nitrifying capacity 

 (N. C.) regards the fitness of a soil outside of the sphere of micro-oi'ganisms.. 

 in other words, the capacity to support nitrification if the proper micro- 

 organisms are present. Nitrifying efficiency (,N. E.) considers the function 

 of the soil as a whole to produce nitrates as an end product. Ammrioificatiam 

 508 



