220 EXPERIMENT STATION RECORD. [Vol.40 



soil was maintained at 60 or 80 per cent of its water-holding capacity. In the 

 40 and 20 per cent series, the osmotic concentration of the soil solution after 

 the addition of the nutrient solution was greater than that of the nutrient 

 solution itself. By adding the nutrient solution to the sand at any of these four 

 moisture contents its osmotic concentration increased, this being attributed to 

 the formation of acid or acids with the high moisture content, and to the forma- 

 tion of acid or acids and the adsorption of water with the low moisture content. 



The adsorptive and the absorptive capacity of the soil for salts prevented the 

 effect of these two agencies from becoming noticeable in the change of the 

 osmotic concentration of the soil solution in the Sassafras light sandy loam 

 with GO and 80 per cent of the water-holding capacity. The osmotic concen- 

 tration of the soil solution at the end of the growing period (30 days) was 

 smaller than that at the beginning of the experiment The decrease was 

 greater in the sand than in the soil, and also in the lower moisture content 

 than in the higher moisture content of either the sand or the soil. 



The nutrient solution consisting of 0.4 gm. ammonium sulphate, 0.S gm. 

 monopotassium phosphate, 2 gm. calcium carbonate. 0.2 gin. magnesium sul- 

 phate, and 0.05 gm. ferrous sulphate per 2 kg. of sea sand cultures with a 

 moisture content equivalent to 80 per cent of the water-holding capacity was 

 benefited by the additional application of magnesium sulphate and ferrous 

 sulphate and also by small applications of potassium chlorld, sodium chlorid, 

 sodium nitrate, calcium sulphate, and sodium Blllcate, The beneficial effect of 

 these salts on plant growth was attributed to the Improvement In the balance 

 of the ions of the component salts in the resultant soil solution. Aluminum 

 sulphate under similar conditions had Caused some injury to plants. The 

 rigidity of the straw of plants was modified by different salts added to the 

 nutrient solution. A proper balance in the nutrient solution was found to he 

 •ntial for the rigidity of the straw. The lodging effect of the large 

 amount of nitrogenous material may be entirely subdued by modifying the 

 proportions between the component salts in the nutritive solution in sand 

 cultures. 



When the evaporation of water from the surface of the sand or of the BOU 

 was taken together with the transpiration of water by plants, it was found 

 that the water requirement of plants diminished with an Increase in plant 

 yield, and vice versa. The use of water by plants in Sassafras light Bandy 



loam was mosl economical with a moisture content equivalent to 10 per cent 

 of the water-holding capacity, and was followed by that of 60 and so per cent 



in the order named. If plant-food is the limiting factor in either soil or sand. 

 the variations in the moisture content are said not to affect the plaid growth. 



The germination of seeds of barley was influenced by the same general 

 agencies that affected the growth of the plant, although not to the same extent. 

 Germination in the sand occurred even when the moisture content was redo 

 to 10 per cent of the water-holding capacity (2.4S per cent based on the dry 

 sand), or when it was raised to 80 per cent of saturation I19.IP per Cant 

 water). In the soils the limits in moisture content between which the germi- 

 nation of seeds could normally take place was much narrower. In two soils 

 germination could not occur at 20 per cent of the water-holding capacity, while 

 In no case with the soils studied did it take place below this point. In all of 

 the soils studied germination was retarded at 80 per cent of saturation. In 

 three soils out of four the best germination was observed at -to per cent, fol- 

 lowed by 00 per cent. Treatment of the sand or soil with a nutrient solution 

 at high moisture contents had very little, if any, effect on the germination of 

 barley seeds. With a decrease in moisture content some retardation In seed 



