14 



Eight species of plants representing six families were tested in the 

 plats, namely: Rice, soy beans, bush beans, rachshes, sunflowers, 

 sweet cassava, sugar cane, and pineapples. Six different crops of 

 each plant were grown at various times during the three yeai-s tliat 

 the investigation was in progress, so the results represent the growth 

 made under average weather conditions. It is beheved that the aver- 

 age weights of the six crops represent withLa an accuracy of about 5 

 per cent the comparative growths made on the different soils. 



Since the purpose of the investigation was to determine the effect 

 of a soil constituent upon the ash composition of the plants, it was 

 necessary to cut the plants before they reached complete maturity. 

 If harvested at complete maturity, variations in the ash induced by 

 the soil might liave been obscured by losses in the muieral constitu- 

 ents which take place in the later stages of maturity.' Moreover, for 

 our purpose the seeds or fruits from the plants on the different soils 

 were not so important as the stems and leaves, since the ash compo- 

 sition of the seeds is less affected by the composition of the soil than 

 the vegetative portion of the plant. Wliile the mineral matter of 

 the stems and leaves is assimilated from the soil, the mineral matter 

 of seeds comes from a translocation of the mineral matter already in 

 the vegetative parts of the plant.- 



Soy beans and bush beans were harvested in flower, wliile the 

 leaves were still sound. Radishes were grown to the proper market- 

 able size and not to seed. Sunflowers were gi-own until the heads 

 had formed, but were cut before the seeds were filled, in order to 

 secure unwithered leaves. Some of the rice was grown to maturity, 

 while other crops were cut at a very early stage and when the panicles 

 were just appearing. Tliis crop was analyzed at several stages of 

 gi-owth. Sugar cane was grown for 148 days and sweet cassava for 

 122 days. Pineapples were grown ten months. In preparmg the 

 samples for analysis none but sound leaves were used, since the ash 

 content of withered leaves is probably dependent more on the leach- 

 ing to which they have been subjected than to influences of the soU. 



The methods used for the aiuxlysis of the plant ashes were essen- 

 tially those of the Association of Official Agricultural Chemists. The 

 ignition of the dry substance was carried out at a low temperature 

 without the addition of calcium acetate, as the hme in the original 

 substance could be determined more accurately without tliis addition. 

 Comparative analyses made of the dry substance ignited with and 

 \sdthout calcium acetate showed that in the absence of the acetate 



1 WiUarth, Romer, and Wimmer(Landw. Vers. Stat., 63 (1905), No. 1-2) have shown that considerable 

 losses of potash and nitrogen oociir during the ripening of wheat and barley. Le C!erc and Brcazeale (U.S. 

 Dep. Agr. Yearbook, lUO.S, p. 38'.i) have also shown that there is a loss of mmeral constituents, particularly 

 at maturity, due to the leaching action of rain or dew. 



2 See Fittbogen, J., Landw. Vers. Stat., 6 (1864), p. 47-1; quoted by Dikow, A. von, Jour. Landw., 39 

 (lS91),p. 134. 



