210 NITROGEN, PHOSPHORUS AND POTASSIUM 



These results show that the plant, as well as the animal, requires a 

 "balanced ration" to enable it to use its food materials most 

 economically. This emphasizes the necessity of keeping a balanced 

 condition in the soil in regards to the fertilizing elements. 



No general rule can be given for fertilizing soils, since condi- 

 tions are so variable and soils differ so widely in their characteris- 

 tics. A certain fertilizer may prove a "best fertilizer" for one soil, 

 while on another it may be of no value whatever. The only sure 

 way of determining the fertilizer needs of a crop on any particular 

 soil is by actual field tests. How the fertilizer needs of soils and 

 crops may be determined is discussed fully. 



High Grade Fertilizers More Economical. High grade fertil- 

 izers are usually considered as those containing a relatively large 

 amount of plant-food elements. Another distinction is: High 

 grade fertilizers are made of high grade, standard materials like 

 nitrate of soda, ground bone, acid phosphate, muriate and sulfate 

 of potash. The low grade preparations, on the other hand, 

 are usually made by mixing cheaper, inferior and less soluble 

 materials, like low grade tankage, wood ashes, kainit, peat, etc. 

 When the amount and quality of the fertilizing ingredients, 

 freight, and cost of handling are considered, the high grades are 

 the cheaper. 



Home Mixing of Fertilizers. By home mixing is meant the 

 mixing of purchased fertilizing materials on the farm. This is 

 commonly recommended, because the cost per pound of plant-food 

 elements is lowered, mixtures can be varied to suit particular 

 soils and crops, and better knowledge is obtained concerning kinds 

 and quality of different materials carrying fertilizing elements. 



The mixing operation is simple. A clean floor, one or two 

 shovels, a pair of scales, and a sand sieve having about four meshes 

 to the linear inch is all the apparatus needed. The materials are 

 first weighed out and placed in a pile on the floor the bulkiest 

 material at the bottom. All lumps are broken with the shovel. 

 The pile is then shoveled over about three times, and the mixture 

 passed through the sieve. Lumps are broken and added to the 

 mixture, which is again shoveled over, if necessary, until thor- 

 oughly mixed: 



Home Mixing Rules. The following rules may be helpful in 

 home mixing: 



(a) Determine the number of pounds of each fertilizing element 

 contained in one ton or any other araount,of theproposedmixture. 



