128 EXPERIMENT STATION RECORD. 



Investigations on the influence of the physical properties of 

 soils on the growth of crops, E. Wolln y ( Forsch, Agr. Phys. [ Wollny], 

 30(1898), ¥o.3, pp. 291-344). — This is a detailed account of experiments 

 during several years with a large variety of crops grown in boxes and 

 pots. The special subjects investigated and reported on in this article 

 are inclination and exposure of the surface of the soil, depth of the 

 cultivated soil layer, fineness of the soil particles, color of the soil, and 

 character of the soil. 



VS ith normal weather conditions and sufficient moisture the greatest 

 yield was obtained on soils having a southerly exposure and the greater 

 inclination (not over 30°). Plants also started growth earlier in the 

 spring on the soils with the greater inclinations. In dry weather, 

 however, the opposite results were obtained. 



There did not appear to be any direct and uniform relation between 

 the depth of the soil and the growth of the plants. 



Within the limits experimented with (less than 0.25 to 2 mm.) the 

 smaller the soil particles the greater the yield. 



Plants germinated more quickly and uniformly and produced larger 

 crops in dark-colored soils than in light-colored soils. 



\Yith approximately the same chemical composition the highest yields 

 were obtained from humus soils; the lowest from sandy soils. 



The experiments show in general that the influence of the physical 

 properties of soils on their productive capacity is of the highest impor- 

 tance and that fertilizers exert a most marked influence upon the 

 physical properties of soils. 



Relative sensitiveness of plants to acidity in soils, W. Maxwell 

 (Jour. Amer. Ghem. Soc, 20 (1898), JVo. 2, pp. 103-107).— The methods 

 followed in the study of this subject are thus described : 



"Two tubs having a diameter of 24 in. and a depth of 20 in. and perforated bot- 

 toms, which were covered with linen cloth, were each tilled with 120 lbs. of air- 

 dried soil of moderate fertility, having a neutral behavior toward acid and alkaline 

 tests. These tubs were placed in tin pans which were 6 in. deep, the perforated 

 bottoms of the tubs being raised 4 in. above the bottoms of the tin pans. The tin 

 pans were filled with water up to the level of the perforated bottoms, and the water 

 was kept up to that level until the soil in the tubs had absorbed moisture to satura- 

 tion, the water absorbed being 48.2 per cent on the water-free weight of the soil. 

 To tub No. 1 enough citric acid was added to make the whole volume of water 

 absorbed a one-tenth per cent solution. To tub No. 2 citric acid was added to make 

 the absorbed water a one-fiftieth per cent solution. In each of the tubs 17 varieties 

 of seeds were planted, these being planted in a circle and equal distances apart. 

 The seeds germinated quickly, were up within four days, and had a healthy appear- 

 ance. After the plants were up and 1 in. high the mode of applying the acid was 

 changed. When the acid was applied in the water absorbed by capillarity from the 

 tin pans it was not equally distributed through the mass of the soil, but was more 

 or less lixed by the bases in the soil at the bottom of the tubs, and did not reach the 

 plants. Therefore the acid was dissolved in water and applied around the plants at 

 the surface. This was controlled by determining the loss of water from the tubs by 

 evaporation and replacing the lost water, with the weight of citric acid dissolved 

 in it necessary to bring up the whole volume of water in the tubs to one-teuth per 

 cent and one-fiftieth per cent solutions, respectively. This was repeated every fourth 

 day." 



