138 HATCH EXPERIMENT STATION. [Jan. 



The Effect of tlie JSfitroyeu. — It will be remembered that 

 nitrate of soda was applied to the four plots receiving this 

 fertilizer in double the usual quantities, viz., at the rate of 

 320 pounds per acre. It increases the crop to a consider- 

 able extent only where it is used in connection with dissolved 

 bone-black. Used in connection with this fertilizer, it gives 

 an increase sufficient, with potatoes at 60 cents per bushel, 

 to much more than cover the cost. The fact that it does 

 not give an increase when used in connection with potash 

 (which as will be seen later was the most useful of the fer- 

 tilizer elements) is strongly indicative of the fact that the 

 soil on the plot receiving nitrate and muriate of potash is 

 once more acid, even on the part limed in 1898. A study 

 of the results leads to the conviction that the experiment 

 furnishes but an imperfect test as regards the necessity of 

 an application of nitrogen on account of the poor ):)hysical 

 and chemical condition of the soil, due to deficienc}^ both of 

 humus and lime. 



77^6 Effect of the Phosphoric Acid. — The dissolved bone- 

 black (furnishing phosphoric acid), when used in connection 

 with either or with both of the other fertilizers, gives an 

 increase more than sufficient to cover its cost. It gives the 

 largest increase in connection with both of the other fer- 

 tilizers, which indicates a high degree of general exhaustion. 

 It gives the smallest increase when used in connection with 

 muriate of potash, which is still further evidence of the 

 probable deficiency of lime, for such deficiency is known to 

 be most marked where muriate of potash is largely emplo}'ed 

 as a fertilizer. 



The Effect of the Potash. — The increase in crop pro- 

 duced by the application of mm-iate of potash, where it is 

 used alone or with either or both of the other fertilizers is 

 in all cases much more than sufficient to cover the cost of 

 the fertilizer. The increase on the limed half of the plots is 

 without exception, if small and large tubers both be included, 

 considerably greater than on the un limed portion of the 

 plots ; indicating that, although there may be a present de- 

 ficiency in the amount of lime necessary for the best results, 

 the effects are not yet wholly exhausted. In practically all 



