306 Mineral Nutrition of Plants 



During 1946 a large shipment of peas was unsatisfactory from the 

 standpoint of cooking. The normal process is to soak the peas over- 

 night, cook in an open kettle, pass through a cyclone to remove skins 

 and hard peas, and then blend into soup. Many lots of the peas grown 

 in 1946 would not cook normally. In fact, some of these peas continued 

 to get harder instead of soft on cooking. Experimental lots cooked 24 

 hours were just as hard as at the beginning of the cooking period. 

 Samples of soil and peas were collected for investigation. The data in 

 Table V summarize this information. The Scotch peas were soaked 



TABLE V 

 Influence of Soil Conditions on the Cooking Quality of Scotch Peas 



*This is a New Jersey soil for comparison. 



overnight, cooked 30 minutes, and then the texturemeter reading was 

 taken. As the calcium and magnesium content of the soils increased, 

 the potassium decreased, and the peas became increasingly hard to cook. 

 Lots of peas that were difficult to cook were electrodialized in the 

 Mattson dialysis cell for 30 minutes, thus removing considerable calcium 

 and magnesium, and then cooked. These became soft before the water 

 boiled. When equivalent amounts of the extracted calcium and mag- 

 nesium were added to the electrodialized peas in the form of chlorides, 

 they again failed to cook properly. In the purchase of dried yellow peas 

 in Canada, it has long been the custom to purchase them on the basis 

 of their suitability for cooking. 



Soils from Warroad, Minnesota, were put in 3-gallon coffee-urn liner 

 pots in the greenhouse for investigation. Increased amounts of potas- 



