Field Truck Crops 243 



In reference to the form of nitrogen, both theoretical 

 considerations and the experience of growers confirm 

 the belief that for the early crop a portion of the nitrogen 

 should exist in the form of nitrate or ammonia and the 

 remainder in quickly available organic forms, although no 

 definite experiments have been conducted to determine 

 this point, nor the one as to whether all of the nitrogen in 

 the form of nitrate should be applied at the time of plant- 

 ing. A top-dressing after the potatoes have come up is a 

 very desirable method of practice on light soils which 

 have been liberally supplied with the minerals. 



On good potato soils, therefore, a good fertilization would 

 consist of 1000 pounds to the acre, as a minimum, of a 

 mixture containing : 



Nitrogen 4% 



Phosphoric acid 8% 



Potash 8% 



The nitrogen is to be in quickly available forms; the 

 phosphoric acid, also, is to be available, and the potash to 

 be derived from sulfate, particularly if fine quality of crop, 

 as indicated by appearance, is desired. If only yield is 

 considered, the muriate is quite as serviceable. 



LATE POTATOES 



For late potatoes, the considerations in reference to the 

 form of the constituents and the amount of the application, 

 as suggested for early potatoes, do not always hold good, 

 since in many cases the crop is able to secure a larger pro- 

 portion of its plant-food from soil sources, due, first, 

 to the longer period of growth of the plant, and second, to 

 the fact that the crop is usually grown upon soils naturally 



