66 SUCCESSFUL FARMING 



would be much more beneficial than in the other. In the same way the 

 results obtained on one farm might not be duplicated on the adjacent 

 farm, although the soil is of the same formation and type, difference in 

 the previous cropping or management of the soil being responsible for the 

 difference in results. 



Which is the Best Fertilizer to Use? This question is a pertinent 

 one, and is often asked by practical farmers. A definite answer can seldom 

 be given. The consumer of fertilizers can best answer it by tests such as 

 above suggested. In a general way, however, the consumer should 

 select those fertilizers which contain the largest amount of plant food 

 in suitable and available forms for the least money. Until a rational 

 scheme of fertilizer treatment has been established it is safest to depend 

 upon high-grade fertilizers used in rather limited amounts. Low-grade 

 materials and elements in slowly available form may prove cheaper for 

 certain soils and crops, but their use involves a larger risk, especially 

 for the farmer who is not well informed on the subject. For soils poor in 

 humus, nitrogenous fertilizers will generally be advisable. For those 

 well supplied with humus, phosphates and potash generally give best 

 results. 



Needs of Different Soils. Since the fertilizer is determined by both 

 soil and crop, the needs of the soil can be determined only in a rather 

 general way. There is no definite statement that will hold under all 

 conditions. A particular soil type in one locality may be greatly bene- 

 fited by a certain fertilizer, while the same type in another neighborhood 

 may have quite a different requirement. 



Heavy soils generally respond to phosphates. Sandy soils are more 

 likely to need potash and nitrogen, while clay soils are generally well 

 supplied with potash. There are some exceptions to this rule. 



Experiments at various experiment stations show that soils vary 

 widely in their fertilizer requirements. The results in one locality may be 

 inapplicable in another. Acid soils respond to application of lime and 

 generally to available phosphates. Marshy soils, especially those con- 

 sisting chiefly of muck or peat, are generally in need of potash and seme- 

 times phosphoric acid and lime. The prairie soils are as a rule deficient 

 in phosphorus, and on such soils the insoluble phosphates are economically 

 used. The need for lime is frequently determined by the failure of clover 

 and the encroachment of sorrel and plantain. Potassium is likely to be 

 needed in soils that have long been exhaustively cropped, especially if 

 hay and straw have been sold from the land as well as the grain. 



Crop Requirements. Crops differ in their fertilizer requirements. 

 This difference is due to the purpose for which the crop is grown, to the 

 length of the growing season required by the crop, and to the period of 

 the season when it makes its chief growth; also to the composition of the 

 crop. It is also influenced by the character of the root systems. Plants 

 which grow quickly generally need their food supply in a readily available 



