KOOT-CKOPS. 61 



results with those on plot 5, with superphosphate without 

 potash as the mineral manure, the evidence of the effects of 

 potash on sugar-production is very marked ; for the increase 

 is very much less under all the conditions of nitrogenous 

 manuring, but especially with the ammonium-salts, where the 

 superphosphate was used without potash. 



This is further strikingly illustrated in the bottom division 

 of the table, which shows the increase of sugar produced for 

 1 lb. of nitrogen supplied in manure. Thus with full supply 

 of potash the increased production of sugar for 1 lb. of 

 nitrogen was — with the nitrate 20.7 lb., with the ammonium- 

 salts 17.8 lb., with the rape-cake 19.6 lb., and with the 

 excess of nitrogen in the ammonium-salts and rape-cake 

 together only 12.8 lb. ; but with the superphosphate without 

 potash the increase was only 17.1 lb. with the nitrate, 8.5 lb. 

 with the ammonium - salts, 12.3 lb. with the rape -cake, 

 and only 5.0 lb. with the excessive amount of nitrogen in 

 the ammonium-salts and rape- cake together. 



Although it is clear, therefore, that the effect on sugar-pro- Sugar and 

 duction of a given amount of nitrogen depended very materi- ^^ure. 

 ally on a liberal supply of potash, the results in the following 

 table (p. 62) show that the amount of sugar for 1 of potash 

 in the roots may vary very greatly according as there is a 

 deficiency or an excessive supply of potash. Thus in the top 

 line of the table we have the amounts of sugar produced for 

 1 of potash in the roots with superphosphate of lime alone — 

 that is, when there was obviously a deficient supply of 

 potash for full sugar-production under the influence of the 

 amount of nitrogen available. Under these conditions it is 

 to be supposed that there would be the maximum produc- 

 tion of sugar for a given amount of potash present. The 

 bottom line shows, on the other hand, the amounts of sugar 

 produced for 1 of potash in the roots where potash was 

 liberally supplied, when doubtless an excess was taken up ; 

 and under these conditions it is seen that the amount of 

 sugar produced for 1 of potash in the roots was in all 

 cases of nitrogenous supply and luxuriant growth less than 

 half as much as when there was a deficiency of potash. 

 Comparing these results with mangels, with those relating to 

 sugar-beet as given on p. 47, it is seen that in the case 

 of that crop, where the same amount of potash was sup- 

 plied, it would, with the much greater amount of sugar 

 produced, not be so much in excess ; the amounts of sugar 

 for 1 of potash in the roots being much greater under the 

 corresponding conditions than with the mangels. 



To summarise in regard to the mangel-wurzel results on summary 

 these various points : There is the more sugar produced °f^ sults > 



