Ixxviii Department of Soil Investigation 



purpose of the investigation now is to ascertain (i) the cause or 

 causes of deflocculation ; (2) the manner in which defiocculation 

 affects the growth of plants. 



Project 5. Effect of soil mixture and ternperature upon the avail- 

 ability and utilization of plant nutrients in the soil. — It is desired 

 to ascertain to what extent the moisture supply affects not only the 

 plant growth, but especially the proportions in which the several 

 nutrients arc absorbed, how this is influenced by changes in the 

 moisture content at different stages in the life of the plant and by 

 changes in the density of the nutrient solution at different stages. 

 As temperature is an importan!: factor in solubility it must be con- 

 trolled. This may have a practical application in irrigation and in 

 the use of fertilizers. 



Project 6. Influence of certain atmospheric conditions on the 

 absorption of mineral nutrients by plants. — Owing to the delay in 

 obtaining a glass house in which the atmospheric conditions can be 

 controlled, this experiment has not been continued. 



Project 7. The character and concentration of the aqueous ex~ 

 tract of the soil under different methods of treatment. — This is 

 really a part of project 5 and will no longer be reported as a sep- 

 arate investigation. 



Project 8. Influence of different methods of soil treatment on the 

 loss of calcium in drainage xvdter. — The decrease in basicity which 

 is a constantly increasing difficulty in soils of humid regions is due 

 largely to the loss of calcium salts from the soil. The rate of loss 

 is possibly influenced by ordinary agricultural practices, as, for ex- 

 ample, clean cultivation, use of fertilizers leaving acid residues in 

 the soil, etc. It is intended to investigate this in the soil tanks. 



Project 9. 1 he loss of potassium and other substances occasioned 

 by manuriiu/ i^'itli lime. — The extensive use of lime necessitated 

 by the acid condition of large areas of soil may have a secondary 

 effect, and by replacing other bases in the polysilicates may result 

 in a considerable loss of potassium in the drainage water. Whether 

 this is the case, and if so, how it may be ameliorated, is the purpose 

 of this investigation. 



Project 10. Extent to zvhich soils under field conditions are re- 

 newed bv accession of lozver soil to the plozved portion. — V>y com- 

 paring productiveness, composition, and certain properties of sim- 

 ilar soils cropped for a long period of years in the soil tanks and 

 in the field it is hoped to discover to what extent the upper layers 

 of soil gain material either by the upward movement in solution 



