MODERN HIGH FARMING. 87 



elements in sufficient quantity to the soil, and even when, by work- 

 ing into the compost heaps a sufficiency of phosphatic materials, we 

 bring up the phosphoric acid to the requisite standard, they will 

 still lack other elements to make them perfect. 



A complete manure may be denned a& that which puts back, in 

 its true proportion, each element taken away by the preceding crop. 

 And to exemplify this, we take a crop of wheat, estimating the 

 average production at 38 to 40 bushels of grain per acre, or at 4,750 

 pounds in weight including the straw. On the basis of our previous 

 calculations, we shall find that this crop has approximately taken 

 from the soil : 



55 pounds of Nitrogen, 



25 " " Phosphoric acid, 



30 " " Potash, 



without counting the lime, the silica and other matters, which we 

 shall presume a good old soil to contain in sufficient quantity ; and 

 that, therefore, if we wish the production to be maintained, the 

 same amounts must be returned. 



Now, the calculation of the requisite quantity of well-made farm- 

 yard manure to represent the nitrogen, can be easily made, since we 

 Imve already shown that in every hundred pounds there is about 

 half-a-pound of this precious fertilizer : 



^ pound Nitrogen = 100 Ibs. farm manure. 



55 pounds " = 11, 000 Ibs. " " or 5^ tons per acre. 

 And our experience has taught us that of all those who farm, say, 

 50 acres of land, there are very few who can produce 275 tons of 

 high- class stable dung ! 



We must consequently look to compound fertilizers of chemical 

 manufacture to supply the deficiency, unless within easy reach are 

 to be found such articles as we have tabulated on page 49, in a 

 form adapted to convenient manipulation. 



So many difficulties are connected, however, with the manu- 

 facture of chemical fertilizers on the farm in arriving at the proper 

 proportions, in the constant attendance to the perfect working and 

 decomposition that we have come to consider the abandonment of 



