DAIRY, SEED IMPROVEMENT, STOCK BREEDERS'" MEETINGS. 299 



from the organic matter o>i the soil and to correct acidity. Tt 

 is also a plant foo'cl and is essential to craps. Clover and al- 

 falfa, in particular, require it. It can be had in the oxide (that 

 is, burned lime), the water-slaked (hydrated lime), or the car- 

 bonate (air-slaked lime and ground limestone.) Lime and 

 ashes tend to make a soil alkaline and an alkaline soil is favor- 

 able to the growth of the fungus which produces potato scab. 

 Hence care should be taken that large amounts of ashes and 

 lime are not lapplied to a soil wlhere potatoes are to be grown. 



Commercial Supplies oe Plant Food. 



MINERAL AMMONIATES. 



Calcium cyanamid at present prices is probably the cheapest 

 source of commercial nitrogen today. The amount that can be 

 safely used in mixed goods is limited, probably not more than 

 200 pounds per ton. Cyanamid nitrogen contains free lime 

 and hence is incoanpatible wdth sulphate of ammonia, and also 

 if allowed tO' stand in mixed goods, it might have a tendency to 

 revert the phosphoric acid. Nitrate oif soda is the most speedily 

 available of all ammoniates. Cyanamid nitrogen is probably 

 as available as sulphate of ammonia and more available than 

 dried blood. In a cold climate such as ours and with crops like 

 potatoes which demand early growth, nitrate of soda is valua- 

 ble and it will probably have to be used in our climate in 1916 

 despite its high price. 



Sulphate of ammonia gave as good results as nitrate of soda 

 with potatoes at Aroostook Farm last year, but plot experiments 

 indicate that it is only from 75 to 80 per cent as available as 

 nitrate of soda. 



orcanic ammoniates. 



These practically all come from refuse sources. Alost of 

 the organic ammoniates are high in price, but they will still 

 have to 'be used in 'mixed goods to a consideraible extent. Tank- 

 age, cotton-seed meal, blood and fish are the standard sources. 

 People living near the wool factories in Maine may find wool 

 waste a valuahle source of nitrogen. It also will carry some 

 potash. Wool Avaste should ibe .composted before using. Along 

 the shores, if they can be cheaply obtained, starfish are quite a 



