1902.] PUBLIC DOCUMENT — No. 33. 37 



It will bo noticed that the employment of nitrate of soda 

 alone results in a considerable increase both in the first and 

 second cuttings, but its effect in increasing the crop is com- 

 paratively small here, no doubt because the soil of that 

 plot must be quite deficient in both phosphoric acid and 

 potash. It will be noticed that the increase produced by 

 the nitrate of soda is greater where it is used with other 

 fertilizers. It gives the greatest increase where used with 

 potash alone, though much the best crop is secured where 

 it is used in combination with both potash and dissolved 

 bone-black. The effect of the dissolved bone-black when 

 used alone amounts to nothing ; when combined with potash, 

 or with both nitrate and potash, it appears to be very 

 useful. This is undoubtedly due to the fact that its pres- 

 ence is favorable to the growth of clover, which, as will 

 be seen from the tables below, is very abundant on those 

 plots where bone-black and potash are used together. The 

 abilit}^ of clover to thrive in the presence of suitable- 

 amounts of bone-black, potash and lime is well known. 

 The crops on the plot where the dissolved bone-black 

 and potash have been so long used, and without any addi- 

 tion of either manure or fertilizer which furnishes nitrogen 

 during the entire thirteen years, afford a striking object 

 lesson. Here we have a yield at the rate of 1,900 pounds 

 of hay to the acre in the first crop and 1,500 pounds in 

 the second. Such crops are far above the average under 

 much more expensive systems of manuring. They are ac- 

 counted for by the capacity which clover grown under such 

 soil conditions as must exist on this plot possesses to draAV 

 the needed nitrogen from the air. It will be noticed that 

 the potash alone gives but a moderate crop, but when used 

 in combination with either of the other fertilizers or with 

 both of them the result is a large increase. As will be 

 seen from the table below, the plots where the potash is 

 used are characterized by relatively large percentages of 

 clover, while there is no clover on the plots to which no 

 potash has been applied. Especially striking is the large 

 increase in the rowen crop where potash is used in connec- 

 tion with dissolved bone-black, — an increase due almost 



