22 maine agricultural experiment station. i916. 



Sulphate of Ammonia Compared with Nitrate op 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 nitrogen, 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 sulphate 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 nitro- 

 gen on the potato crop. In earlier publications it has been 

 pointed out that the potato 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 nitro- 

 gen should be immediately 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 

 increasing use of high grade organic nitrogen for food of 

 animals, the price of tankage has been going higher and higher 

 year by year. It is, of course, desirable, if it can be done, 

 that as much as possible of this sulphate of ammonia, which 

 is a comparatively cheap source of nitrogen, be used in Maine 

 fertilizers. 



Because of these facts, arrangements were made to begin 

 in 19 14 a series of experiments to run over a period of several 

 years. The "base" which was used in these goods was made 

 by the wet process, whereby nitrogen from rather low grade 

 goods is made as available as from high grade goods. The 

 available phosphoric acid was furnished in the form of acid 

 phosphate and the potash in the form of sulphate of potassium. 

 The fertilizer was free from chlorides so as to preclude the 



