be $96.77, hence the gain clue to manure has been $58.71, while 

 the chemicals have given a gain valued at $62.55. 



It will be interesting to see how the amount of deficient 

 plant food in the fertilizer compares with that contained in the 

 excess of crop, over that produced without fertilizer. 



In the table showing the plant food removed by various crops 

 I have computed the amounts removed b}' average crops, or 

 perhaps by what might be termed good crops, in the table on 

 page 25 is arranged the plant food, taken by each crop on acres 

 three and four, and also on the plots having no manure. The 

 difference shows the drain upon the land by the increased yield 

 marked {difference to co7ne from fertilizer.) While the last column 

 marked {furnished in manure or chemicals) shows the plant food 

 furnished in the manure, and also in the chemicals for the 

 whole period. 



It will thus be seen that in the acre fertilized with Chemi- 

 cals there has been applied about four times as much phosphoric 

 acid and nearly two times as much potash as was removed by 

 the excess of crop over the natural production of the land, but 

 only a little over one-third as much nitrogen was provided as the 

 crops would seem to require. It is true that certain quantities 

 of ammonia are yearly brought down in the rain, but this is off- 

 set by the loss in drainage water, we must conclude therefore 

 that more of the soil nitrogen is rendered available each year 

 than there is of the phosphoric acid or potash, and that the ap- 

 plication of one or both of these latter substances would increase 

 the yielo without the aid of nitrogen, and as has already been 

 shown, the potash is the element that controls, and nitrogen is 

 comparitively useless. 



There can be no doubt, that there is still potash and phos- 

 phoric acid enough left in the acre fertilized with chemicals, to 

 give two or three more good crops of hay and it is quite prob- 

 able that the supply of nitrogen will not fail. 



On the acre with manure we are not so certain of our figures 

 for the analyses of the manure is an average one taken from 

 many sources but is probably somewhere near the truth, the 

 phosphoric acid is about the same as that supplied in the chemi- 

 cals, but the potash is considerably greater, while there has been 

 a most wasteful amount of nitrogen applied. Allowing that 

 there was need of supplying the whole excess of 93.47 pounds 



26 



