VI.] 



EFFECT OF POTASH ON MANGOLDS 



169 



the two plots possessed practically the same leaf 

 development, working under identical conditions of 

 illumination, carbon dioxide, and water supply. But 

 in one case the photo-synthetical process had been 

 limited by the want of potash ; all the machinery was 

 there and the power was in excess, but the machinery 

 was running idle for the lack of one necessary link — in 

 this case the potash : — 



Table XLV.— Effect of Potash on the Produce of Mangolds 

 at rothamsted, 1900. 



Plot. 



Manure. 



Leaf 

 per acre. 



Roots 

 per acre. 



Sugar 

 per acre. 



5A 

 4A 



Ammonium Salts and Superphos- 

 phate ..... 



Ammonium Salts, Superphosphate, 

 and Potash . . • . 



Tons. 

 2'95 

 3-25 



Tons. 

 12 00 

 28-95 



Tons. 

 0-797 

 2-223 



The effect of potash upon the mangold crop is also 

 to be seen upon the plots where dung is also supplied, 

 as shown in Table XLVI. : — 



Table XLVI.— Rothamsted Mangolds (12 years, 1895-1906). 



Here it will be seen that potash increased the crop 

 in every case, except where nitrate of soda had been 

 used as the nitrogenous cross dressing, in which case 

 the soda liberates so much potash from the soil that 



