22 



Journal of Agricultural Research 



Vol. XVI, No. I 



such result. The greater absorption of sulphur trioxid occurs in the 

 only plot treated with great quantities of sulphates, but the increase 

 is not great. 



In some cases a marked increase in a given constituent accompanies 

 the presence in excess of some other ion. This is seen in the plot treated 

 with sodium sulphate, in which potassium absorption in both root and 

 top is high. A similar result is seen in the plots treated with stable 

 manure and with both acid and basic complete mixtures. On the 

 other hand, potassium absorption is decreased in the acid-phosphate 

 plot in both tops and roots. Potassium chlorid in excess also accom- 

 panies a reduction of potash in the ash of both parts of the plant. 



Silica is greatest in plots receiving calcium carbonate and acid phos- 

 phate, lowest in those dosed with sodium salts, and in the control plot. 



It is interesting to note that, although the manganous oxid content 

 when referred to dry weight is small in all cases, it is consistently higher 

 in the roots than in the tops, acid complete mixture excepted, this being 

 the only constituent which is not more abundant in the tops than in 

 the roots. 



RATIOS BETWEEN PAIRS OF CONSTITUENTS 



In a number of cases there seemed to be some evidence that a roughly 

 reciprocal relation exists between pairs of constituents. This tendency 

 was most marked in the plots receiving mixtures of salts. Thus, in 

 general, when silica was high, potash was low in both tops and roots. 



The silica-potash ratios, as worked out for the different plots, are 

 summarized in Table II. 



Table II. — Silica-potash ratio in ash of spinach plants. Silica (5i6>2)=/ 



Potash (K2O). 



Fertilizer. 



Sodium nitrate. .. . 

 Sodium sulphate . . 

 Sodium chlorid ... 

 Potassium chlorid . 

 Calcium carbonate 

 Acid phosphate . . . 



Complete acid 



Basic complete . . . . 



Manure 



Control 



It will be noted that, while both of these constituents belong to the 

 group of the more variable ones, the ratio is less variable; silicia being 

 unity, potash lies between i.oo and 2.00 in a majority of cases. In 

 plots receiving heavy doses of calcium -containing fertilizers (calcium 

 carbonate and acid phosphate) as well as in the tops from the sodium- 

 chlorid plot, the silica exceeds the potash. Again, potash has high 



