ROOT-CROPS. 43 



growth than during the three years, generally only about 

 half as much as over the preceding period ; but, as above 

 stated, the amount was greater in proportion to the dry sub- 

 stance produced — the supply of potash being the same, but 

 the available nitrogen and the consequent growth much less. 

 Further, as over the three years, so now over the two years 

 with only residual nitrogenous supply, and very much less 

 growth, the percentage of potash in the dry matter of the 

 leaf is very much higher than in that of the root ; but also 

 as over the three years, the actual quantity of potash per acre 

 in the leaf is very much less than that in the root. 



As to the phosphoric acid, its percentage in the dry sub- Phosphoric 

 stance of the root is fairly uniform throughout the live acid m the 

 series with the same supply of it by manure, but with great 

 difference in the available supply of nitrogen and in the 

 amounts of growth. The amounts of phosphoric acid per 

 acre in the roots are, however, by no means uniform in the 

 different series, but have a very obvious relation to the 

 quantities of dry substance grown. The percentage of phos- 

 phoric acid in the dry substance of the leaf is also pretty 

 uniform throughout the different series; but the quantities 

 per acre in the leaf, as in the root, have distinct relation to 

 the amounts of growth. They are, however, in all cases 

 much smaller than those in the root, and very much smaller 

 than the amounts of potash in the leaf. 



The relation of the potash and phosphoric acid to the 

 amount of substance grown will be further referred to 

 presently. 



The following Table (13) shows — in the upper division the Produce 

 percentage of sugar in the sugar-beet roots under the °/ su ff ar - 

 specified different conditions of manuring ; in the second 

 division the amounts of sugar yielded per acre (in lb.) ; in the 

 third division the increase of sugar per acre by the nitro- 

 genous manures ; and in the bottom division the increased 

 amount of sugar for 1 lb. of nitrogen supplied in manure. 

 The mean results are given for the three years of the direct 

 nitrogenous supply, for the two years of residual supply 

 only, and for the five years, three with, and two without, the 

 direct supply. Further, the results are given both for plot 

 5 with superphosphate only as the standard or mineral 

 manure, and for the mean of plots 6 and 4, the former with 

 superphosphate and potash, and the latter with superphos- 

 phate, potash, soda, and magnesia, as the mineral manure. 



It may in the first place be observed that the percentage Effect of 

 of sugar is about one and a-half time as high as in mangel- JJSS^? 

 roots grown under similar conditions as to manuring. Re- of sugar. 

 ferring to the results for the first three years, the table shows 

 that the percentage of sugar is the highest in Series 1 — that 



