246 SOILS AND FERTILIZERS 



will generally furnish the necessary available plant 

 food. Instead, however, of providing the one element 

 needed, others which may already be present in the soil 

 in- liberal amounts are often supplied at an unnecessary 

 expense, instead of being made available by cultivation. 

 Another abuse of fertilizers is their application to the 

 wrong crop. A heavy application of potash fertilizer to 

 a wheat crop grown on a rich clay soil, or of nitrate of 

 soda on land seeded to clover, or of land plaster to flax 

 grown on a limestone soil, would be a waste of money. 



294. Judicious Use of Fertilizers. In order to make 

 the best use of commercial fertilizers, both the soil and 

 the crop must be carefully considered. All soils do not 

 alike respond to commercial fertilizers, and farm crops 

 possess different powers of assimilating food ; turnips, 

 for example, have very restricted power of phosphate 

 assimilation, hence they require phosphate manures, and 

 wheat may need help in obtaining its nitrogen. A 

 wheat crop will starve for want of nitrogen, while an 

 adjoining corn crop will scarcely feel its need. Wheat 

 has strong power of assimilating potash, while clover 

 has less. Hence in the use of fertilizers the ability of 

 the plant to obtain its food must be considered. A 

 light application of either a special purpose or a com- 

 plete fertilizer at the time of seeding is often advanta- 

 geous, as it encourages plant growth by supplying food 

 when it is most needed. There should be some at this 

 time in a highly available condition for the use of the 



