Field Truck Crops 255 



richer in nitrogen and potash than in phosphoric acid. A 

 mixed fertilizer composed of : 



Nitrate of soda 300 Ibs. 



Bone tankage 500 Ibs. 



Acid phosphate 800 Ibs. 



Muriate of potash 400 Ibs. 



would contain, approximately, 75 pounds of nitrogen, 

 156 of phosphoric acid and 200 of potash in each ton. 

 An application of 1000 pounds to the acre of this mixture 

 would furnish nearly half as much nitrogen as is contained 

 in a crop of ten tons, a surplus of phosphoric acid, and an 

 equal amount of potash. Hence a dressing containing the 

 amounts, kinds and proportions of plant-food here shown 

 would be regarded as very desirable, since one-half of 

 the nitrogen is in the form of a nitrate, which would con- 

 tribute to the immediate growth of the plant. The 

 amount of soluble and available phosphoric acid is suffi- 

 cient to satisfy the needs of the crop throughout its entire 

 growth, and such an abundance of potash as to contribute 

 to the normal development of both plant and fruit. For- 

 mulas of this character have been used with good results, 

 though the large proportion of salts sometimes make 

 mixtures of this sort too moist to handle well, in which 

 case a part of the potash, or even of the nitrate, may be 

 applied separately with advantage. On poorer soils, 

 the artificial supply of plant-food should be proportionately 

 greater, or sufficient to provide for the entire needs of a 

 fair-sized crop, since as a rule the relative power of the 

 plant to acquire food is somewhat slighter on poor soils 

 than on good soils ; or, stated in another way, the results 

 from the use of fertilizers are proportionately better upon 

 soils in good condition than upon those not well cared for. 

 A good formula for these may consist of : 



