72 



tion, with the formation of a corresponding amount of 

 calcium sulphate. The increased productiveness then, 

 may have been due to the precipitated manganese com- 

 pounds, or to the stimulating action of calcium sul- 

 phate, or to the sulphur applied. In discussing these 

 results. Skinner and Reid state that "The action of 

 manganese in decreasing the oxidation in the soil while 

 acid is in harmony with the decreased yield, and its 

 action in increasing the oxidation of the neutralized 

 soil is in harmony with the increased yield. The ac- 

 tion of manganese in the acid soil was probabl}' to stim- 

 ulate the life processes in the soil, acting on the organic 

 matter in such a way as to produce changes which re- 

 sulted in a lessened crop-producing power, while its 

 action in the neutralized soil was such as to stimulate 

 oxidation and other biological processes, acting on the 

 organic soil constituents and producing changes favor- 

 able to the growing plants." 



Skinner and Reid's view as to increased oxidation 

 due to manganese sulphate applied to a basic soil is 

 substantiated by the work of Greaves (5) who, working 

 with a soil which was clearly basic from the analysis 

 given, found that moderate amounts of manganese sul- 

 phate stimulate ammonification. Brown (2) has pub- 

 lished the results of similar studies, with results similar 

 to those obtained by Greaves, with respect to ammoni- 

 fication. However, the data obtained by Brown in his 

 studies on nitrification would seem to indicate that his 

 soil was acid, since there was little or no nitrification of 

 ammonium sulphate in four weeks. 



In discussing the peculiar soils of Hawaii, Kelley (9) 

 states that "In Hawaii the growth of certain crons is 

 enormously influenced by the mere burning of small ac- 

 cumulations of brush and undergrowths of Ciuav.-i and 

 lantana. The effect on cotton on the uplands of Oahu 

 produced by these small fires may represent the dif- 

 ference between success and failure. The color and 

 vigor of the crop on these small areas dotted here and 

 there over a field attract attention. Other crops are 

 affected similarl3\" Again he says "A field plowed 

 for the first time, although the soil be thoroughly ])ul- 

 verized and reduced to a state of fine tilth, usually will 

 not support plant growth satisfactorily. The farmers 

 of Hawaii have found it necessary to areate newly 

 plowed lands for a period of several months before 

 planting the first crop. It has been observed, however, 

 that excellent growth of crops is obtained on the small 



