304 AGRICULTURE OF MAINE. 



acre. Other than the amount of potash used, all the plots were 

 treated exactly alike. 



Throughout the growing season the vines on both the no 

 potash plots were a distinctly brighter green and had a thriftier 

 look than on the adjoining plots. The difference was so marked 

 that it attracted mudi attention from visitors at the farm. 

 Although some slight irregularities occurred in the yield from 

 the different plots, the average figures show fairly consistent 

 increases with the increase in potash. The plots without potash 

 yielded no barrels or 302 bushels of merchantable potatoes. 

 The plots with two and five per cent potash gave practically 

 the same yields of 116 barrels or 320 'bushels per acre. The 

 eight per cent potash plots averaged to yield 120 barrels or 331 

 bushels per acre. This is an increase of ten barrels from the 

 eight per cent plots over the no potash plots. This amount is 

 undoubtedly large enough to be significant and to indicate that 

 the potash increases the yield of potatoes in Aroostook county. 

 On the other hand, no barrels (302 bushels) per acre is a good 

 yield — considerably above the average and nearly double the 

 average in the county in 191 5. So far as the results of this one 

 year are concerned, they indicate that a profitable yield of po- 

 tatoes can be obtained on Aroostook soils without the addition 

 of potash for at least one year. In a few farmers' trials made 

 by the various fertilizer companies, in which no exact records 

 were made, satisfactory results were obtained without the use 

 of potash by all of the growers from whom the Station has 

 heard. Quite a number of farmers tested mix'tures containing 

 varying amounts of nitrogen, phosphoric acid and without pot- 

 ash. The consensus of opinion seems to be that a five per cent 

 ammonia and ten per cent phosphoric acid gave on the whole 

 the best yields. Based upon the reports of these trials, a good 

 many of the fertilizer companies are increasing the amount of 

 phosphoric acid the present year. Fertilizers that normally 

 carried eight per cent will in 19 16 carry ten per cent available 

 phosphoric acid. To the speaker this increase in phosphoric 

 acid does not seem to be necessary. Outside of the special fer- 

 tilizer experimental plots at Aroostook Farm and at Highmoor 

 Farm, the fertilizer to be used in 19 16 will carry five per cent 

 ammonia (with one-third of the nitrogen in the form of nitrate 



