170 SOILS AND FERTILIZERS 



Exercise III. — Comparison of fertilizer effects on plant 

 growth. 



Materials. — Fertilizers, flower pots, poor sandy soil, oat seed. 



Procedure. — It may be of advantage to compare two or more 

 of the nitrogen fertilizers with reference to their effect on plant 

 growth. Fill flower pots with the same amount of a poor 

 sandy loam after thoroughly mixing the fertilizer with the soil. 

 Apply nitrogen fertilizers at the rate of 250 pounds per acre (1 of 

 fertilizer to 1 0,000 of soil) . Also add at the same time acid phosphate 

 and muriate of potash at the rate of 1 to 5000 of soil respectively. 

 One gram of lime per pot is also necessary. Leave one pot untreated 

 with the nitrogen fertilizers as a check. Now plant oat seeds and 

 bring the soil to optimum moisture content. When seedlings are 

 a week old thin to proper number. Keep pots in suitable place and 

 observe relative development of the plants under the different treat- 

 ments. 



