84 BOTANICAL GAZETTE [February 



and noncalcareous soils, but had no efifect on phosphorus. Lip- 

 man and McLean (42) found that composting rock phosphate 

 with sulphur increased the solubility of phosphorus. McLean 

 (48) found an increase of solubility of phosphorus in the sulphur- 

 rock phosphate compost when compost was inoculated. The 

 presence of soluble phosphates and sulphates did not inhibit the 

 action. Lipman, McLean, and Lint (43) found a great increase in 

 acidity in the sulphur-floats mixture. Lipman and Joffe (41) 

 found no increased availability in phosphorus when acidity was 

 increased by the addition of sulphuric acid. Ellett and Harris 

 (20) found greater availability of phosphorus in a manure-soil- 

 floats-sulphur compost than in a soil-floats-sulphur compost. 

 Ames and Richmond (2) found no increased availabihty of 

 phosphorus in a compost to which calcium carbonate had been 

 added. Acid conditions are necessary for the solution of the 

 phosphorus. Brown and Gwinn (id) found an increased solu- 

 bility of phosphorus in soil treated with sulphur as well as in com- 

 posts. Brown and Warner (12) found no increased solubility 

 of phosphorus in a manure-floats compost, but a great increase 

 when flowers of sulphur were added to the compost. 



The use of gypsum as a preservative of the nitrogen in manure 

 has been investigated by Heinrich (30), Vivien (71), Nolte (53), 

 and by Ames and Richmond (i). All these investigators report 

 a saving of nitrogen from the use of gypsum on the manure. 



Investigations on the efifect of flowers of sulphur on the avail- 

 ability of potassium in greensands were conducted by McCall 

 and Smith (45). They found an increase in the availability of 

 potassium in composts of sulphur, greensands, and manure, but 

 no increase in availability of potassium in composts of sulphur, 

 greensands, and soil. 



Reports of investigators who studied the influence of gypsum 

 on the availability of potassium do not agree. McCool and 

 Millar (46) found calcium sulphate applied to soil lowered the 

 freezing point of the soil. No report was given as to the character 

 of the compounds that lowered the freezing point. Bradley (4) 

 found an increase in solubiHty of potassium but not of phosphorus 

 in Oregon soils. Briggs and Brezeale (6) found a decrease in 



