48 MAINE AGRICULTURAI, EXPERIMENT STATION. I915. 



this, arrangements were made to begin in 1914 a series of experi- 

 ments 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 possibility of the formation of 

 poisonous ammonium chloride. The base carried approximatel}- 

 one-third of the nitrogen that went into the formula. The 

 remainder of the nitrogen was furnished in the form of nitrate 

 of soda and sulphate of ammonia, as indicated in the following 

 plan: 



Plot I. Basal mixture and 2-3 of the nitrogen in form of 

 nitrate of soda. 



Plot 2. Basal mixture and 2-3 of the nitrogen in form of 

 sulphate of ammonia. 



Plot 3. Basal mixture and 1-3 of the nitrogen in form of 

 nitrate of soda and 1-3 in form of sulphate of ammonia. 



Plot 4. Basal mixture, and 1-3 of the nitrogen in form of 

 high grade organic and 1-3 in form of nitrate of soda. 



Plot 5. Basal mixture and 1-3 of the nitrogen in form of 

 high grade organic and 1-3 in the form of sulphate of ammonia. 



There was about an acre in each plot. The Lowell Strain 

 Green Mountain potato was used for seed. The fertilizer was 

 applied at the rate of 1500 pounds per acre, and supplied about 

 60 pounds of nitrogen, 120 pounds of available phosphoric acid 

 and 105 pounds of water soluble potash per acre. Other than 

 the fertilizer used the plots were planted, cultivated, sprayed 

 and cared for in all particulars alike. 



May and June were rather cool months and hence would be 

 favorable to the nitrate of soda. The mean temperature for 

 May was 53.2 degrees, for June 56.0 degrees, July 63.5 degrees, 

 August 60.1 degrees and September 55.8 degrees. There were 

 several cold nights with frosts in June. May 4 the thermometer 

 went to 25 degrees, May 5 to 32 degrees, June 9 to 30 degrees 

 and June 28 to 31 degrees, and on this latter date there was 

 quite a heavy frost so that it injured potatoes, not in these ex- 

 periments but on some other plots at Aroostook Farm. The low- 

 est temperature in July was 40 The lowest temperature in 



