FERTILIZER INSEECTION. IO5 



by laboratory tests compared favorably with other equally high 

 grade brands offered in Aroostook county in 1907. The nitro- 

 gen was practically all in the form of tankage of good grade and 

 sulphate of ammonia. While in the opinion of the writer, it is 

 desirable that a potato fertilizer for Maine and particularly 

 Aroostook county carry nitrate nitrogen, there is nothing in the 

 fertilizer law or the guaranty given by the R. T. Prentiss Com- 

 pany respecting the form of the nitrogen. The nitrogen which 

 was used is practically as high priced a form as nitrate nitrogen. 

 As is well known, the season of 1907 was unfavorable for the 

 growth of potatoes in Aroostook county; the late wet spring, 

 the wet summer, the conditions favoring blight, and the early 

 freezing all tended to make it difficult to obtain a satisfactory 

 crop of potatoes. There seems to be quite a widespread dis- 

 satisfaction among the users of the R. T. Prentiss Company's 

 goods, and the Station has received frequent letters asking if 

 this can be due to the quality of the fertilizer. It is evident that 

 the R. T. -Prentiss Company's Aroostook Complete Potato 

 Fertilizer was about 9 per cent short in its constituents, but a 

 fertilizer carrying in good form 2.83 per cent nitrogen, 5.63 per 

 cent available phosphoric acid and 9.45 per cent potash is still a 

 high grade concentrated fertilizer. Applied as liberally as it was 

 in most cases, it is doubtful if in a field experiment a difference 

 between a fertilizer of this composition and one with the guar- 

 anteed analysis would show decisive results. Twelve hundred 

 pounds to the acre of a fertilizer as shown by the analysis would 

 carry 34 pounds of nitrogen; 68 pounds available phosphoric 

 acid and 113 pounds of potash. A crop of 300 bushels of 

 potatoes removes in the tubers about 55 pounds of nitrogen; 25 

 pounds of phosphoric acid and 85 pounds of potash. On six- 

 teen hundred pounds of a fertilizer carrying 3 per cent nitrogen, 

 6 per cent available phosphoric acid and 5 per cent of potash, 

 the Station grew in Houlton in 1907 on a measured acre of land, 

 167^ barrels (460 bushels) of merchantable potatoes. This 

 fertilizer furnished 48 pounds of nitrogen, 96 pounds available 

 phosphoric acid and 100 pounds of potash. Sixteen hundred 

 pounds of Prentiss Aroostook Complete, on the average as 

 analyzed would furnish 45 pounds of nitrogen, 90 pounds of 

 available phosphoric acid and 151 pounds of potash. 



