CHAPTER XXVI 



SHORT-TIME POT-CULTURE AND WATER-CULTURE EXPERI- 

 MENTS IN COMPARISON WITH FIELD RESULTS 



THE United States Bureau of Soils has developed methods of 

 making culture experiments in paraffined wire pots and in water 

 extracts of soils, which it was hoped would furnish information from 

 two or three weeks' growth of seedling plants that would serve as 

 a useful guide in determining the fertilizer requirements of the soil. 



TABLE 108. EXPERIMENTS ON WOOSTER (OHIO) SOIL 



Comparison of Ohio Field Experiments with Bureau of Soils' Pot Cultures for 



determining Needed Elements of Plant Food 



(a) OHIO STATION'S NINE YEARS' TEST IN FIELD 

 Average Increase in Yield per Acre 



(b) BUREAU OF SOILS' TWENTY-DAY TEST IN POTS 

 Weight of Green Tops (Increase only, in Grams) 



N = nitrogen; P = phosphorus; K = potassium. 



1 Increase in clover and timothy hay. 



5*3 



