1 410 



SOIL PHYSICS, CHEMISTRY AND MICROBIOLOGY 



Table I. — Moisture intake of Xanthmm seeds in osmotic solutions , 

 temperately e 23.50 C; intake in percentage of air-dry weight. 



Solutions 

 volume molecular 



I hour 



4 hours 7 hours 



ID hours 24 hours | 48 hours □ 



o ji a 



H 2 O 



0.1 M — Na CI . 

 0.2 M — Na CI . 

 0.3 M — Na CI . 

 0.4 M — Na CI . 

 0.5 M — Na CI . 

 0.6 M — Na CI . 

 0.7 M — Na CI . 

 0.8 M — Na CI . 

 0.9 M — Na CI . 

 i.o M — Na CI . 

 2.0 M — Na CI. 

 4.0 M — Na CI . 

 Sat. — Na CI . 

 Sat. — Na CI , 



16.39 



16.79 



17.12 



16.07 



14.36 



13.96 



13-80 



13.32 



13-13 



12.58 



11.90 



8.19 



4.81 



3-42 



0.67 



44-38 

 39-43 

 38.67 

 34-05 

 31.21 

 30.26 

 25-57 

 26.29 

 25.22 

 24-34 

 22.92 

 14-55 

 8.37 

 4.94 

 ■ 0.77 



48.78 

 45-87 

 45.00 



40-75 



38.08 



35-87 



32-41 



30-99 



29.21 



27-64 



25.42 



18.25 



9.84 



5-24 



— 0.58 



51-18 

 46-39 

 45-93 

 42.24 



40-33 

 38-70 

 34-77 

 32-79 

 31.12 

 29.14 

 26.21 

 18.60 

 11.00 

 6.21 

 I— 0.58 I— 0.58 



50.38 



46.48 



45-57 



41-95 ! 



39-97 1 



38-oS 



33-57 



31-73 I 



29-95 



28.95 



26.48 



18.43 



10.08 



51.58 

 46.33 

 45-52 

 42.05 

 40.27 

 38.98 

 35-18 

 32.85 

 31-12 

 29-79 

 26.73 

 1855 

 11.76 



6-35 

 ' 0.29 



0.0 



3-8 



7.6 



11.4 



15.2 



19.0 



22.8 



26.6 



30.4 



34-2 



38.0 



72.6 



130.0 



375.0 



965.0 



to be in equilibrium. Though by no means exact the calculations are 

 near enough to the osmotic determinations to be of great interest. 



The earliest soil measurements were made with No. 2) sand. Seeds 

 of known weight were packed firmly in sand of knowTi water content in 

 paraffined wire baskets, and allowed to come to equilibrium. The tests 

 were confined finally to the region of soil moisture from air-dry to the wilt- 

 ing coefficient, because with a higher moisture content the seeds always 

 became saturated with water. In the case of this sand it was not until 

 the water content was reduced to about i per cent that a noticeable " back 

 pull " was developed by the soil. 



This method is obviously open to the criticism that fiiction retards the 

 movement of water in dry soils, and that the seeds therefore do not reach 

 actual equilibrmm with the total soil mass, but only witlf the soil lying 

 near them. In order to meet this difficult}-, a rotation method (bottles 

 arranged on rotating wheels driven by a motor) was adopted which brings 

 the seeds constantly into contact with fresh soil particles. 



