MISCELLANEOUS 425 



Soil Studies 



Peats and composts. McCool ^^ made a study of widely different classes 

 of peats as substitutes for the ever-diminishing supply of manure. The 

 peats varied in mineral content from 3.45 to 53.75 per cent, in nitrogen 

 from 1.78 to 3.35 per cent and in pH from 3.39 to 6.85. Under storage they 

 showed considerable but variable nitrate formation. When added in large 

 amounts along with complete fertilizers, and lime for the more acid peats, 

 they brought non-productive mineral soils to a high level of fertility. Use 

 of peats ^^ in composts increased nitrification and plant growth, but differ- 

 ent peats varied considerably in effectiveness. A partly decomposed, sedi- 

 mentary, fibrous peat, when composted Avith fertilizer salts, Hme, and a 

 small amount of manure, proved to be a valuable soil improver. It was 

 superior to the same material mthout composting. Straw disintegrated 

 readily when composted ^\ith the peat mentioned above and with proper 

 amounts of fertilizer salts and lime ; it was more effective for soil improve- 

 ment than equal amounts of commercial manures. A number of factors ^^ 

 were found to modify the pH of peats. In some peats increasing the water 

 content increased the pH by 1, while in others adding water had little 

 effect. Oven-drying of peats had little effect upon the pH when they were 

 again soaked, although the effect was measurable in some cases. Air-drying 

 increased the soluble salt content of some peats and oven-drying was more 

 effective. Very acid peats were rendered far less acid by leaching with 

 large volumes of distilled water. The less acid peats showed slighter 

 changes. Addition of salts to peats including fertilizers increased the 

 acidity of peats. Salts with bivalent cations were more effective than salts 

 of monovalent cations and less acid peats were more modified than more 

 acid ones. It took heavy applications of super phosphate and complete 

 fertilizers to change the pH noticeably. 



A study *^ was made of various methods of composting several kinds of 

 plant materials (leaves of oak, Norway maple and sugar maple, pine leaves, 

 salt-marsh hay, straw and cat-tail plants) and the value and best methods 

 of applying the several composts to soils. Additions of cyanamide greatly 

 hastened the decomposition of leaves, pine needles, and cat-tail composts. 

 The acidity of leaf composts decreased rapidly upon standing, and salt- 

 marsh hay composts were alkaline. Adding the uncomposted materials to 

 soil decreased crop growth; oak leaves and some other composts also 

 decreased crop growth if added to soils alone, but proved very beneficial 

 if added with complete fertilizers. A domestic peat composted with cyana- 

 mide alone proved injurious; but when composted with cyanamide plus a 

 still greater amount of acid phosphate it was beneficial to the growth of rye. 



Soil solutions. Following the suggestion of Knudson and Ginsburg that 

 the density of juice pressed out of plant tissue varied Avith the amount of 

 pressure used, McCool and Youden ^' determined the acidity of successive 

 samples of water pressed out of ground tissue of several plant organs and 



