71 



most favourable circumstances. Artificial manures 

 can be obtained which supply the manurial require- 

 ments of the crop at less cost than when they are 

 in the form of dung. Under most circumstances it is 

 more profitable to use the two in conjunction than 

 either one singly. The average composition of a 

 6-ton crop of potatoes, with 18 cwt. of haulm, has 

 been estimated as follows : Of ash in tubers 126 Ibs., 

 of ash in haulm 50, total 176 Ibs.; of nitrogen 

 47 Ibs. in tubers and 20 Ibs. in haulm, total 67 Ibs. ; 

 of sulphur 2*7 and 2' 1, total 4-8 Ibs.; of potash 75*4 

 and 1-1, total 76*5 Ibs.; of soda 2 and 2, total 4 Ibs.; 

 lime 2-9 and 22-7, total 25-6 Ibs.; of magnesia 5-7 

 and 12-4 Ibs., total 18'L Ibs.; of phosphoric acid, 

 24-1 and 2'7, total 26'8 Ibs. ; of chlorine 3-5 and 1-9, 

 total 5-4 Ibs.; of silica, 2-9 and 2-1, total 5 Ibs. In 

 heavier crops the quantities would be proportionately 

 increased. Nitrogen, potash, lime, and phosphoric 

 acid are therefore present in greatest quantity, and 

 must be supplied. These are supplied in dung, 

 though all fertile soils contain them in some quantity. 



The following analyses were made by Dr. Munro in 

 connection with the Warminster experiments, and are 

 specially valuable for the remarks which accompany 

 them. The "Potato Manure" mentioned was a 

 special compound purchased. 



SOOT. The sample of soot contains : 



Moisture 5 '92 



Organic Matter .. 68 -68 containing Nitrogen 5 '17 

 Mineral Matter ... 25 '40 Phosphoric Acid 0.30, 



and Potash 0'86. 

 100-00 



