KOOT-CKOPS. 49 



with the turnips and sugar-beet; and following the sugar- 

 beet, they were commenced in 1876, and are still continued 

 — the last crop, that of 1894, being therefore the nineteenth 

 in succession. We propose to draw our illustrations from 

 results obtained in the field during the 17 years, 1876-92, 

 and in the laboratory during shorter periods. 



Table 14 (p. 50) gives the average produce — roots, leaves, 

 and total — over the 17 years for six plots, each with five 

 different conditions as to nitrogenous supply. 



A glance at the table shows that the produce of roots of Mangels 



the mangel-wurzel is on a much higher level than that of "^J™"' 

 oti o'~ . nips com- 



either common or Swedish turnips, and there is also much pared. 

 more leaf. There was, however, a general similarity in 

 amount of produce obtained under similar conditions of 

 manuring with the mangel as with the sugar-beet. Compared 

 with turnips, the mangel-seed is sown earlier, and the plant 

 has a longer period of growth. It has a much more deeply 

 penetrating tap-root, throws out a less proportion of its feed- 

 ing-roots near the surface, and exposes a comparatively large 

 area of leaf to the atmosphere. With its more extended 

 root-range, it is less dependent on continuity of rain when 

 growth is once well established; and it bears, or rather 

 requires, for full growth a higher temperature than the 

 turnip. These conditions determine in what localities it is 

 most suitably grown in this country. But where the soil and 

 climate are suitable, very much larger crops can be obtained 

 than of turnips. The mangel requires, however, very heavy 

 dressings of manure if it is to yield full crops. 



The Table (14) shows that with farmyard manure alone, Dung and 

 which was applied at the rate of 14 tons per acre per annum, su ^P ?hos ' 

 there was an average produce of 15| tons of roots, and that 

 the addition of superphosphate of lime increased it very little. 

 This result, compared with that with turnips, is quite con- 

 sistent with the difference in the character and range of the 

 feeding-roots of the two crops ; and it is also quite consistent 

 with common experience in the matter. 



Notwithstanding that the amount of farmyard manure Nitrogen- 

 employed would supply annually about 200 lb. of nitrogen ous man ' 

 per acre per annum, it is seen that the addition of specially 

 nitrogenous manures greatly increased the crops. Thus the 

 average produce was raised from 15 tons 10 cwt. to 21 tons 

 8 cwt. by the addition of nitrate of soda, to 21 tons 1 cwt. by 

 ammonium-salts, to 22 tons 18 cwt. by rape-cake, and to 23 

 tons 16 cwt. by ammonium-salts and rape-cake together. Mineral 



With purely mineral manure the produce of this more alone and 

 powerfully rooting plant is much higher than was obtained with nitr0 ' 

 with Swedish turnips by the same manures. The addition manures, 



VOL. VII. D 



