1918] SOILS FERTILIZERS. 321 



and uniform in texture to a depth of at least 10 ft. and containing approxi- 

 mately 40 per cent calcium and magnesium carbonates. Various amounts of 

 irrigation water were used, and 1-ft. sections of soil taken to a depth of 10 ft. 

 were collected at different intervals of time before and after the irrigation 

 treatments. The results are discussed in some detail and pictured diagrammati- 

 cally, and may be briefly summarized as follows : 



A marked similarity was apparent in the content and distribution of moisture 

 in soils producing potatoes and sugar beets. The efficiency of the water de- 

 creased with the amount applied, 1-in. weekly applications showing a greater in- 

 crease in moisture to a depth of 10 ft. in proportion to the amount applied than 

 either 2.5, 5, or 7.5 in. weekly and also gave a higher crop yield. 



The initial percentage of moisture in the soil influenced the distribution of the 

 irrigation water applied. Furrow irrigation was found to be more effective in 

 conserving moisture than flooding. The lateral movement of soil moisture after 

 irrigation was slow, particularly in the upper feet 



A straw mulch proved to be more effective in moisture conservation than an 

 earth mulch, and the latter more effective than no mulch with the weeds pulled, 

 although after the eighth day the differences were so small that the advisability 

 of mulching hinged on the question of labor. When no irrigation water was ap- 

 plied the soil retained as much moisture where the weeds were pulled as where 

 the soil was cultivated. 



The crop was able to reduce the soil moisture to a depth of 10 ft., the differ- 

 ence in the moisture content of cropped and uncropped soil decreasing with an 

 increase in the amount of irrigation. 



Manure had very little effect upon the distribution of moisture in the soil. 



It is concluded that the application of more irrigation water than is actually 

 required to satisfy the needs of the crop is a wasteful practice. 



The rate of water movement in aerated soils, H. E. Pulling {Soil Sci., 4 

 {1911), No. S, pp. 239-268, fiffs. 13). — Osmometer experiments conducted at the 

 University of Wisconsin on nontoxic, nonsaline black sandy loam garden soil and 

 sandy soil are reported and discussed. A form of osmometer specially adapted 

 to the study of mass or molar movement of the soil water is described and its 

 methods of use are explained in detail, as are the reducing and plotting in form 

 of graphs of the data obtained. 



A list of 22 references to literature on the subject is given. 



The shrinkag'e of soils, H. A. TsifPANY {Jour. Agr. Soi. [England], 8 {1917), 

 No. 3, pp. 312-330, figs. 4)-— Experiments are reported in which by determina- 

 tion of the internal pore space in blocks of soils and comparison with the ob- 

 served value for the linear shrinkage it was found that a linear relationship 

 appeared to exist between the two values. This relation is expressed by the 

 equation 



C=(3a-jj2-f^j, 



in which 0=the percentage of cubical contraction and a the percentage of linear 

 contraction. 



By extrapolating the curve thus obtained an approximation for the limiting 

 value of the shrinkage in the case of pure colloidal clay was arrived at amount- 

 ing to approximately 23 per cent. On this assumption it was possible to calcu- 

 late the approximate content of colloidal material in any soil from a knowledge 

 of the linear shrinkage. Results are adduced showing the values obtained for 

 the shrinkage in the case of separated fine silt and clay fractions in the case 

 of two soils of known shrinkage and physical composition and compared with 

 the values calculated from previous assumptions. The results of the calcula- 



