DIVISION OF SOILS. 135 



FUTURE WORK. 



It is proposed to investigate as thoroughly as possible during the 

 coming year the apparent forces between soil particles, and the floccu- 

 lation of clay. The imi^ortance of such a research is at once evident, 

 when we consider that the unproductiveness of many soils is due 

 primarily to the compact, unyielding mass resulting from the apparent 

 forces between soil grains. A satisfactory metliod of bringing soils 

 of this kind into a more friable condition, so essential to proper plant 

 development, would be of untold value to our agricultural interests, 

 and is worthy of the most earnest research. 



It is also projjosed to investigate during the coming year the diffu- 

 sion of salts in the capillary spaces of soils. This has never been 

 investigated in a manner applicable to our work, and the information 

 is necessary before proceeding further with the study of the distribu- 

 tion of soluble salts in the soil formation of hardpau, and many 

 kindred problems. 



LABORATORY OF SOIL CHEMISTRY. 



The work of the past year has involved the examination of a large 

 number of soils, irrigation waters, rocks, minerals, and similar mate- 

 rials, sent in by the field parties, together with furnishing data of a 

 miscellaneous character to others. In addition to this routine work, 

 a number of investigations have been carried on which have yielded 

 results of considerable economic importance, as well as of scientific 

 interest. 



The work on the chemical composition of type soils from Mar3dand, 

 which had been undertaken some time before under the joint auspices 

 of the Maryland experiment station and this Department, was brought 

 to a conclusion. The results have been published in Bulletin No" 70 

 of the station. The principal needs of the soils with respect to fer- 

 tilizers were so clearly brought out as to justify suggestions with a 

 considerable degree of confidence. 



The study of the effect of certain soluble salts which find applica- 

 tion as mineral fertilizers on type soils has been carried on and results 

 of interest have been obtained showing that the solubility of the 

 mineral components of the soil are much affected thereby, generally 

 in the direction of an increased solubility. The importance of this 

 work for a rational control of the fertilizing problem is thoroughly 

 appreciated, but it is not advisable to give details of the work at the 

 present stage of the investigation. 



CHEMICAL PROPERTIES OF THE MOISTURE IN SOILS. 



Further attention has been given to the subject of soil solutions, or 

 the nature and composition of the material dissolved in the ground 

 waters which are present in all arable soils. The importance of 

 investigations along this line for making clear the chemical and 

 chemico-physical processes taking place in the soil, the relation of the 

 plant to its mineral nutrients, and the development of rational methods 

 of fertilizing, is becoming more evident with the progress of the work. 

 The nature and function of soil solutions has been discussed in a 

 publication from the Division during the year in which the role of 

 water, iron, calcium, carbon dioxide, hydrous silicates, organic mat- 

 ter, etc., is carefully considered, together with adsorption by soils, 

 soil acidity, and related jDhenomena. 



