206 SOILS AND FERTILIZERS 



3. What is a high-grade in distinction from a low-grade fertilizer ? 



4. Explain what is meant by a filler. 



5. What, in a general way, does a report on the inspection of a 

 fertilizer show ? 



6. How are trade values of plant nutrients evaluated ? 



7. What are the advantages to be derived from the home mixing 

 of fertilizers ? 



LABORATORY EXERCISES 



Exercise I. — Fertilizer inspection and control. 



Fertilizer laws are designed to protect the honest manufacturer 

 as well as the farmer. Obtain the laws of your state which have to 

 do with fertilizer inspection and control. Analyze them step by 

 step with this point always in mind. Decide whether or not the 

 law does really regulate and protect in the way that it should. A 

 study of fertilizer bags and tags could also be made with profit. 



Exercise II. — Laboratory mixture of fertilizers. 



Materials. — Sodium nitrate, dried blood, acid phosphate, 

 muriate of potash, sulfate of potash, balances, dry soil as a filler. 

 You must have the guaranteed composition of each carrier. 



Procedure. — Make 2000-gram lots of the following mixtures. 

 Fertilizers must be dry and fine. Put through sieve if necessary. 



No. 1. — Make up 2 kilos of a 3-7-10 fertilizer, using sodium 

 nitrate, acid phosphate and muriate of potash. Add filler as nec- 

 essary. 



No. 2. — Make up a fertilizer as above, using dried blood, acid 

 phosphate and sulfate of potash. 



Allow these mixtures to stand for some weeks and compare. 

 Also compare them as to physical condition with a ready mixed 

 fertilizer of a similar guarantee. 



Exercise III. — Home mixture of fertilizers. 



If possible cooperate with some farmer in the mixing of fertilizers. 

 Allow the pupils to check all calculations and to aid in the actual 

 mixing of the goods. The pupils should also understand the pro- 

 cedure of selecting and ordering the fertilizer carriers in order that 

 every step in the process may be familiar to them. The educational 

 value of a study of the crop, soil, fertilizer and rotation is a strong 

 point in favor of home mixing. 



