88 BOTANICAL GAZETTE 



FEBRUARY 



La WES and Gilbert (36) found, in their fertilizer experiments 

 with red clover, that ''the produce was considerably increased by 

 the application of gypsum, and still more so by that of the sul- 

 phates of potash, soda, and magnesia, and superphosphate of lime." 

 In four years the increased yield from the use of gypsum was 3.5 

 tons of dry hay, or an average of 0.9 ton per acre per year. 



Hunt (35), at the Pennsylvania Agricultural Experiment Sta- 

 tion, used gypsum in a rotation of corn, oats, wheat, and hay 

 (timothy and clover). Gypsum was applied at the rate of 320 

 pounds per acre per rotation in two appHcations, 160 pounds to 

 the corn and 160 pounds to the wheat. No other fertilizers were 

 used, and no increases in yields were obtained from the use of 

 gypsum. These experiments would be more valuable if the gypsum 

 had been applied to the clover and other fertilizers had been used 

 to remove the possibility of another limiting factor. 



Miller (51) grew clover in pots containing Oregon soils. 

 Applications of sulphur were made in the form of flowers of sul- 

 phur, sodium sulphate, and gypsum. Gypsum and sodium sulphate 

 gave increased yields, but the flowers of sulphur had little effect. 



ScHREiNER (61) studied the effect of different salts on oxida- 

 tion in soil extracts in which wheat seedlings were grown. He 

 reports increased oxidation from the use of calcium sulphate, 

 potassium sulphate, and sodium sulphate. 



Dymond, Hughes, and Jupe (18) compared the effect of 

 ammonium sulphate and ammonium chloride on cabbages grown 

 on non-calcareous soil. Greater yields were obtained with the 

 ammonium sulphate than with the ammonium chloride. In their 

 experiments with clover they obtained a 20 per cent increase in 

 hay from the use of gypsum. In pastures they observed that 

 legumes predominated where sulphates were appUed, and grasses 

 where no sulphates were used. Gypsum increased the yields of 

 red clover, maize, and vetch in sand cultures, and of vetch in soil 

 cultures. All the pots received applications of calcium and mag- 

 nesium carbonates. 



LiPMAN and Gericke (40) compared the effects of different 

 nitrogenous fertilizers on barley grown on Oakley's vitro sand, and 

 found the greatest increase with ammonium sulphate. When 



