SOILS FERTILIZERS. 321 



iug adequate aeration of the soil. Moreover, wlien tlie irou exists in tlie 

 ferrous state, and the soil can not be aerated, the use of fertilizers gives little 

 or no benefit. It is therefore necessary to adopt a rational soil program with 

 the central idea, that of securing a better aeration and better physical proper- 

 ties of the soil. Studies, which are designed to throw light on the practical 

 methods of accomplishing such a result, are now in progress at the station, and 

 the suggestions, already made by the station chemist, are being put into 

 practice in a number of localities. It may be truthfully said that in many 

 localities the chief soil problems are concerned with the physical leather than 

 the chemical properties of the soil. Improper aeration not only causes the 

 iron to become reduced to the ferrous state, but may also prevent the utiliza- 

 tion by the plant of the plant food naturally present in the soils." 



The Hawaii Station is studying, by means of pot and field experiments, 

 cultural and rotation methods for securing better aeration of the soil. 



Deli soils, J. G. C. Vriens and S. Tijmstra (Medcd. Dcli-Procfstat. Medan, 

 5 (1911), ^os. 6, iUK 1J,5-161 ; 8, pp. 259-295, map i).— In this article, which 

 reports a continuation of investigations (E. S. R., 24, p. 713), results of studies 

 on the relation of various physical soil factors to each other and to the chemi- 

 cal constituents of the soil are reported. Among the more important conclu- 

 sions reached are the following: 



The nitrogen-fixing power and the water-holding capacity varied with the 

 fineness of the soil, being highest from the fiuest soils. A high nitrogen-fixing 

 power was associated with a high water capacity, a low absorptive capacity, 

 and a low porosity, whereas a low nitrogen-fixing power indicated a low water 

 capacity. A high nitrogen content was associated with a high water capacity 

 and a low absorptive capacity, whereas a low nitrogen content indicated a 

 low water capacity and high pos'osity, A .medium to high phosphoric acid 

 content was associated with a high water capacity and a low volume weight ; 

 a good phosphoric acid content went with a high absorptive capacity and a 

 high porosity. A high potash content went with a low retentive power with a 

 decrease In volume, whereas a low potash content indicated a high water 

 capacity, a medium retentive power with increase in volume, a low volume 

 weight, high absorptive capacity, and high porosity. A high lime content went 

 with a high nitrogen -fixing power and a high water capacity. No definite 

 relation between lime content and absorptive capacity, volume weight, and 

 porosity could be established. 



Deli soils, J. G. C. Vbiens (Meded. Deli-Proefstat. Medan, 4 (1910), No. 6, 

 pp. 177-180; 5 (1911), No. 8, pp. 255-257).— This is a continuation of the report 

 on the analyses of tobacco soils previously noted (E. S. R., 23, p. 224). 



Methods and results of ten years' soil investigations in Illinois, C. G. 

 Hopkins (Illinois Sta. Circ. 149, pp. 12-32, figs. 5). — This is an address delivered 

 before the Illinois State Farmers' Institute in February, 1911, and gives an 

 account of the plan, purpose, and progress in three lines of soil investigation 

 carried on by the Illinois Experiment Station, (1) soil surveys, (2) soil analyses, 

 and (3) culture experiments. 



A list of firms from which natural rock phosphate, bone meal, potash salts, 

 and ground limestone may be obtained is added. 



Results of scientific soil treatment, F. I. Mann (lUinois Sta. Circ. 149, pp. 

 3-11, figs. 5). — This is an address delivered before the Illinois State Farmers' 

 Institute in February, 1911, and deals with the method of soil improvement, 

 namely, use of raw phosphate in a rotation of cereals and leguminous plants, 

 recommended by the Illinois Experiment Station. 



The natural plant food content and fertilizer requirements of soils, 

 F. LEmEN (Gartenflora, 60 (1911), N.os. 2, pp. 25, 26; 5, pp. 94-106) .—This is a 



