102 EXPERIMENT STATION EECORD. 



activity of soil organisms. Several "species of anaerobic or facultative 

 anaerobic bacteria were found in abundance in the soil, where they 

 developed Avith great rapidity, forming butyric acid wherever there 

 were roots or other organic matter capable of supplying the requisite 

 carbohydrates. Experiments in destrojdng the bacteria showed that 

 by the injection into the soil of carbon bisulphid, creolin or other 

 germicides, the trouble was corrected. The cost of the carbon bisul- 

 phid required for the treatment is so great as to make its use almost 

 prohibitive on a field scale, and as a consequence a number of experi- 

 ments are in progress to bring the treatment within the range of 

 economic use. 



A study is also in progress on the catalase of soils ; and as bacteria 

 are one of the chief sources of catalase, the soil treatment mentioned 

 above is found to have an inhibiting effect on the catalytic action of 

 soils. 



In Hawaii studies of the soil were among the earliest scientific 

 investigations taken up by the station. The total nitrogen content of 

 some of the soils was found to be higher than the crop production 

 would indicate, and investigations showed much of the nitrogen to be 

 present in organic forms that are not available for plant growth, if 

 not actually detrimental. 



Much attention has been given to the study of pineapple soils. In 

 certain sections pineapples do not thrive. The young plants start off 

 well, but in a few months the leaves turn j^ellow and many of the 

 plants never bear fruit, or if any is produced it is inferior in both 

 size and quality. An examination into the probable causes for this 

 showed the presence of an unusual amount of manganese in the soils, 

 in some cases as much as 5 per cent of manganese oxid. Such soils 

 are black and apparently very fertile, but the manganese forms a 

 deposit about the roots, interfering Avith their functions. The degree 

 of yellowing of the plants was found to be in direct proportion to the 

 percentage of manganese present. The red soils of the islands showed 

 less manganese and were better adapted to pineapple growing than 

 the black type, the dark color of which is attributed to the presence 

 of the higher oxicls of manganese. Experiments are in progress to 

 correct the influence of abnormal amounts of manganese, and in the 

 meantime the planting of this crop on such soils is advised against. 



Another study which has connection with soil work is the use of 

 commercial fertilizers in the growing of rice. The rice soils of 

 Hawaii are largely of volcanic origin, and in spite of the submerged 

 culture they j^uddle very poorly and there is a great loss of fertilizers 

 through leaching. As a result of studies made by the station, the 

 substitution of sulphate of ammonia for nitrate of soda has been fol- 

 lowed with excellent results. These experiments also indicate that 

 the oriental practice of applying a considerable amount of the fer- 



