114 Barn and Field Experiments in 1916 



as little as 45 pounds per acre of potash increased the yield of 

 potatoes at least when grown on sod land. The amount of this 

 increase depends upon the condition of the land and probably 

 also upon the seasonal conditions. The results obtained this 

 year on sod land indicate that it paid to use goods with 2 per 

 cent potash even at the present abnormal price. Second, a pro- 

 fitable yield of potatoes can be obtained without the use of 

 potash for at least one year. If it should happen that potash 

 is absolutely unobtainable, growers may still plant on land that 

 is in good heart with the prospect of obtaining a profitable 

 yield. 



SULPHATE OF AMMONIA COMPARED WITH NITRATE 

 OF SODA AS A SOURCE OF NITROGEN IN 

 POTATO FERTILIZERS AT AROOS- 

 TOOK FARM. 



A few years ago there was quite a general failure of the 

 crop of potatoes in Aroostook County where a certain brand of 

 fertilizer was used. This fertilizer was analyzed by the Station 

 chemists and found to be high grade. While it was not quite 

 up to its guaranty in some particulars it did carry enough nit- 

 rogen, phosphoric acid and potash to more than grow a good 

 crop of potatoes. This fertilizer carried none of its nitrogen in 

 the form of nitrate of soda, but it was all in the form of sul- 

 phate of ammonia and high grade organic materials. This led 

 to the stronger reaffirming of the position which the Station 

 had taken relative to the use of nitrate nitrogen in the potato 

 crop. In earlier publications it has been pointed out that the po- 

 tato makes its demands for nitrogen early in the season and 

 that in the cold, late springs so common in Aroostook County, 

 the crop demands that part of the nitrogen should be immedi- 

 ately available. For this reason the Station has strongly urged 

 that about one-third of the nitrogen in a potato fertilizer be 

 nitrate nitrogen. 



In the process of making gas and coke from coal there is 

 developed a large amount of sulphate of ammonia, which in 

 many coke and gas plants is still going to waste. In some 

 plants this now is being conserved and many thousand tons of 

 sulphate of ammonia are thus obtained each year. With the in- 



