272 SOILS AND FERTILIZERS 



ally, and at the end of five hours observe the comparative amounts 

 of insoluble matter remaining in the beakers, also the color and 

 appearance of the solution in each beaker. See Section 158. 



Experiment No. 26. 

 Preparation of Fertilizers. 



Mix in a box 200 gms. acid phosphate, (saved from Experiment 

 2 4) 50 grams kainit, and 50 gms. sodium nitrate. Calculate the 

 percentage composition of this fertilizer and its trade value. 



Experiment No. 27. 



Testing Ashes. 



Test samples of leached and unleached ashes in the way de- 

 scribed in Section 240. 



Experiment No. 28. 



Extracting Water Soluble Materials from a Commercial Fertilizer. 

 Dry and weigh a 7 cm. filter paper. Fit it in a funnel, and place 

 in it 2 gms. of commercial fertilizer. Pass through the filter, a 

 little at a time, a half litre of pure water at about 40 deg. C. (dis- 

 tilled water preferred). Transfer the filter paper and contents to 

 a watch glass, dry in a water oven, weigh and calculate the per 

 cent, of material extracted by the water. If the fertilizer is made 

 of such materials as acid phosphate, kainit, muriate or sulphate of 

 potash, nitrate of soda and sulphate of ammonia, from 60 to 90 per 

 cent, will dissolve. Inspect the insoluble residue and note if it is 

 composed of dried blood, bones or animal refuse materials. In a 

 high grade complete commercial fertilizer, from 40 to 80 per cent, 

 or more should dissolve in water. 



Experiment No. 29. 



Influences of Continuous Cultivation and Crop Rotation upon the 

 Properties of Soils. 



For this experiment, a soil that has been under continuous culti- 

 vation, and also one of a similar character from an adjoining field 

 where the crops have been rotated and farm manures have been 

 applied, should be used. Make the following determinations with 

 each soil : 



Weight per cubic foot. 



Capacity to hold water. 



