350 



CASSELL'S POPULAE GARDENING. 



—of Grasses nearly 95 per cent., and of species repre- 

 senting other orders less than 5 per cent. 



On the other hand, the plot receiving mineral 

 manures alone — which are of little avail for Grami- 

 naceous crops grown separately in rotation, but which 

 favour Beans, Peas, Clover, and allied plants— has 

 given, on the average, 43 species. Of these, 17 in 

 number are Grasses, 4 Zeguminosce, Sind. 22 belong to 

 other orders; but, by weight, the percentage of 

 Grasses has averaged only 65, that of the Legumi- 

 nos<B nearly 20, and that of species belonging to other 

 orders less than 15 per cent. 



obtained whan the soil supplies a liberal amount of 

 both carbonaceous and nitrogenous matter (as well 

 as mineral constituents) , and when they are already 

 available within the soil, or are supplied in the fonn 

 of farmyard manure, rape-cake, Peruvian guano, 

 ammonium salts, nitrate of sodium, &c., the rapidity 

 of growth and the amount of the crop are greatly 

 increased by the use of superphosphate of lime 

 applied near to the seed." 



Effect of Different Manures on the Growth 

 OF Norfolk White Turnips at Rothamsted. 



Effect of Manure on Koot Crops..— We 



now turn our attention to the so-called root crops ; 

 and the cultivation, habit, and uses of these |)lants 

 are well suited to form a contrast to those of the 

 cereal crops, or to those of the various species found 

 in the mixed herbage of grass land. The results, 

 previously quoted, of the Eothamsted experiments 

 upon Wheat and Barley, members of the Gramina- 

 ceous family, have shown that not only is the soil 

 the main source of the nitrogen of these crops, 

 but also that the character of exhaustion which 

 the soil suffers by their growth is primarily nitro- 

 genous. 



The greatly varying forms and outward appear- 

 ance of plants, implying essential differences in the 

 sources of nutriment, have led, from but superficial 

 observation of them, to false assumptions regarding 

 their growth. Thus it is by some maintained that 

 the large surface of leaf put forth to the atmosphere 

 by the Turnip and allied plants bespeaks an almost 

 exclusive reliance upon the natural resources of the 

 atmosphere for their carbonaceous supply ; and the 

 direct application of nitrogenous manures has ac- 

 cordingly been recommended, with the view of 

 favouring to the greatest extent the development of 

 leaf as a means of securing bulb. 



After forty years' experimenting at Rothamsted on 

 various members of the root-crop family, Lawes and 

 Gilbert say : " It is impossible adequately to state the 

 bearing of the results in a few words, but the follow- 

 ing are some of the most characteristic indica- 

 tions : " — 



"1. Without manure of any kind, the produce 

 of roots was reduced in a few years to a few cwts. 

 per acre ; but the diminutive plants (both root and 

 leaf) contained a very unusually high percentage of 

 nitrogen. 



2. Of * mineral ' constituents, phosphoric acid 

 (in the form of superphosphate of lime) was by far 

 the most effective manure ; but, when this manure is 

 used alone, the immediately available nitrogen of the 

 soil is rapidly exhausted. 



" 3. Really large crops of Turnips can only be 



Description of 

 Manure. 



Produce per Acre. 



Bulb. 



13 



1 13 

 9 8 

 10 4 



Leaf. 



14 



1 



18 

 8 9 

 3 12 



Without Manure . 

 Sulphate of Am- 



monia, 3 cwts. . j 

 Rape-cake, 10 cwts. 

 Calcined Bone- ) 



dust, 400 lbs. . f 

 Superphosphate ) totq o'qic 



of Lime . . r ^1 ^ 



Superphosphate 



and Eape-cake 

 Farmyard Dung, ) ^ 



12 tons . .] ^' ^ 



Increase over' 

 Unmanured. : 3 



Bulb. I Leaf. 



03 . to 05 



VI ' a 



- ^ ^ o e 



19 10 3 



8 15 oj 7 15 



9 10 2 2 18 



12 



13 18 1 5 14 2^13 

 3|16 



7 7 



3 3 2 



2j 5 



6 13 



I 



0-11 



22 



0, o•^^7 



2' 92 



2 118 



I 



1 1 33 



I 



2 1-61 



Comparing the results here given, it is seen that 

 the undecomposed bone-dust and the supherphos- 

 phate tend to increase the size and weight of the 

 bulbs ; while the effect of rape-cake alone, with its 

 excess of nitrogenous constituents, is rather to 

 enhance the leaf-forming tendencies of the plant, 

 which it is true may probably aid carbonic acid accu- 

 mulation from the atmosphere, but at the same time 

 gives a less profitable appropriation of the plant-food 

 resources within the soil. With an application of 

 twelve tons of farmyard manure per acre, the 

 greatest amount of total produce is obtained and 

 the largest average weight of bulb. So far as sup- 

 ply of manurial ingredients is concerned, we may 

 reasonably suppose that every constituent, excepting 

 carbon, was given more fully in quantity, and more 

 favourably for assimilation, in the combination of 

 superphosphate and rape -cake than in the dung ; yet 

 the latter, with its greater carbonaceous supply to 

 the root and root-fibres, yields the largest crop and 

 the heaviest weight of individual bulbs in the 

 series. 



The effect of an equal amount of superphosphate 

 of lime on land ploughed in the ordinary way, com- 



