Barn and Field Experiments in 1917. 37 



POTATOES GROWN AT AROOSTOOK FARM ON 



FERTILIZERS CONTAINING AMMONIA 



(NITROGEN) IN DIFFERENT FORMS. 



A few rears 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 ni- 

 trogen, 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- 

 creasing use of high grade organic nitrogen for food of ani- 

 mals, 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 ferti- 

 lizers. 



Because of these facts, arrangements were made to begin 

 in 1914 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 



