330 Bulletin 179. 



that phosphate was the only plant-food that was useful, and that all 

 the money paid for the other two was wasted. 



Such being tlie results of a number of the experiments with fer- 

 tilizers, it would seem that a wise and prudent farmer would attempt 

 to keep a sort of a bank account with every field on his farm that is 

 under cultivation. To accomplish this, he would charge to each 

 field the cost of the fertilizer applied to it, if he uses commercial 

 fertilizers ; after the harvest he would credit every field with the 

 market value of its produce. It would cost him but little time 

 and labor to measure three plats, say of a tenth of an acre, in each 

 field to be treated with commercial fertilizers, one plat being left 

 unfertilized ; multiplying the yield of each of these plats by ten 

 would give the yield per acre. He has then all the data that are 

 necessary in order that he may learn by a simple calculation whether 

 the increase of the crop has more than paid for the cost of the fer- 

 tilizer used. 



The farmer may say that he cannot spare the time for carrying 

 out this plan ; or he may say that he does not want to lose the 

 increase of crop that the fertilizer would give on the one unmanured 

 plat. But this loss on a tenth of an acre only would be very small 

 and it would be of much more importance to him to know whether 

 he gains or loses by the application of fertilizers. Better still would 

 it be if he could carry on a set of experiments with the three import- 

 ant i^lant-foods in a complete fertilizer in the manner described in 

 the preceding pages. He might then learn that only one of the 

 three foods, say, for example, the phosphoric acid in a plain super- 

 phosphate, or potash, or some combination of two of the three foods 

 is all that the field experimented upon requires, and that money 

 spent for any other food is simply thrown away. 



Frequently during the summer the representative of the Station 

 was asked by the farmers if it would ])ay to use such large quanti- 

 ties of fertilizers as were sent out by the Station and if smaller 

 quantities would not do just as well. The answer was that in these 

 experiments the cost of the fertilizers was not taken into considera- 

 tion, the main object being to find out whether the use of any one 

 or more of the plant-foods would give profitable yields over and 

 above the yield without any fertilizer. For such a purpose it is 



