14 Maine; agricuIvTural e;xperime:nt station. 1905. 



soluble, 158 pounds phosphoric acid, of which two-thirds is avail- 

 able, and 102 pounds potash. 



While the 100 pounds of available phosphoric acid in this 

 formula is about four times the amount removed by the crop, 

 the best experimental evidence indicates that a liberal application 

 of available phosphoric acid is profitable for potatoes. Since 

 phosphoric acid does not leach from the soil, the excess will be 

 available for the following grain and grass crops. Following 

 a crop of potatoes manured as above, usually a good crop of 

 clover could be grown by the use of 200 pounds per acre of a 

 complete fertilizer for a "starter," and 200 pounds of muriate of 

 potash. This last with the phosphoric acid left in the soil would 

 furnish the needed minerals, and the clover would obtain its 

 needed nitrogen from the air. 



Nitrate of soda carries about 16 per cent nitrogen, all of which 

 is water soluble. High grade cottonseed meal, carrying 43 per 

 cent of protein, has about 7 per cent nitrogen, 2 per cent phos- 

 phoric acid and i per cent potash. High grade finely ground 

 bone tankage carries 5 to 6 per cent nitrogen, about one-third of 

 which is water soluble, and about 15 per cent phosphoric acid, 

 one-half of which is available. Muriate or sulphate of potash 

 each carry about 50 per cent potash. 



As the result of correspondence on this subject, the writer 

 assisted farmers in Brunswick, Houlton and Fort Fairfield in 

 mixing goods for use with potatoes. The formula used at 

 Brunswick was : Portland Rendering Company's screened tank- 

 age 500 pounds ; cottonseed meal 200 pounds ; nitrate of soda 

 100 pounds ; acid phosphate 400 pounds ; and sulphate of potash 

 200 pounds. This 1,400 pounds of materials carried nitrogen 

 55 pounds; available phosphoric acid 103 pounds; total phos- 

 phoric acid 154 pounds; and potash 103 pounds. The percent- 

 age composition as found by analysis was water soluble nitrogen 

 1.39 per cent; insoluble nitrogen 2.52 per cent; total nitrogen 

 3.91 per cent; water soluble phosphoric acid 4.51 per cent; cit- 

 rate soluble phosphoric acid 2.84 per cent, making the available 

 phosphoric acid 7.35 per cent; insoluble phosphoric acid 3.67 

 per cent and total phosphoric acid 11.02 per cent; and potash 

 7.38 per cent. This was used by several farmers in Brunswick. 

 The fields were not visited by the writer. Mr. W. S. Morrill, 



