34 



THE ROTHAMSTED EXPERIMENTS. 



Produce 

 ofleaf. 



Table 10 

 explained. 



Propor- 

 tions of 

 leaf and 

 root. 



Composi- 

 tion ofleaf 

 and root. 



nitrate of soda raises the produce to nearly 19 tons, that of 

 ammonium - salts to nearly 15 tons, that of rape - cake to 

 nearly 18 tons, and that of rape-cake and ammonium-salts 

 together to more than 22 tons. It is also seen that during 

 the succeeding two years, when no further nitrogenous 

 manure was used, there was still more or less increase, due 

 partly to the manure-residue of the previous applications, and 

 partly to the increased amount of leaf that had been annually 

 returned to the land as manure where nitrogenous manures 

 had been employed. Thus the average produce over the two 

 years by the mineral manures, including potash, but without 

 nitrogenous manure, was 5 tons 14 cwt., raised where nitrate 

 of soda had previously been applied to 8 tons 13 cwt., where 

 ammonium - salts had been used to 7 tons 12 cwt., where 

 rape-cake to 9 tons, and where rape-cake and ammonium- 

 salts together to 11 tons 6 cwt. 



The summary further shows that over the three years of 

 the application of nitrogenous manures, the produce of leaf 

 was raised from 1 ton 7 cwt. with the mineral manures alone, 

 to 5 tons 2 cwt. by the addition of sodium nitrate, to 3 tons 

 10 cwt. by ammonium-salts, to 3 tons 13 cwt. by rape-cake, 

 and to 7 tons 16 cwt. by rape-cake and ammonium-salts to- 

 gether. Over the next two years, without further nitro- 

 genous manuring, but with some nitrogenous manure-residue, 

 and increased return of leaf to the land, where nitrogenous 

 manures had been applied, the produce of leaf was raised 

 from 1 ton 2 cwt. by the mineral manure alone, to 2 tons 2 

 cwt. where in addition nitrate of soda had previously been 

 applied, to 1 ton 10 cwt. where ammonium-salts had been 

 used, to 2 tons 8 cwt. where rape-cake, and to 3 tons 6 cwt. 

 where rape - cake and ammonium - salts had been applied 

 together. 



The next Table (10, p. 35) which relates to the mean pro- 

 duce of plots 6 and 4 (with potash), over the three years 

 during which the nitrogenous manures were annually applied, 

 shows the proportion of leaf to 1000 of root, some particulars 

 of the percentage composition of the root, and of the leaf, 

 and the amounts of certain constituents per acre in the root 

 and in the leaf. 



The first line of figures shows a range of from 205 to 354 

 parts of leaf to 1000 of root, according to the manure, and 

 the consequent degree of luxuriance and of maturity. The 

 proportion of leaf was thus much higher than in Swedish 

 turnips ; it is also higher than in mangel-wurzel, but much 

 lower than in common turnips. 



The percentage of dry matter in the root is more than 

 twice as high as in common turnips, more than one and a-half 



