22 Subtropical Vegetable-Gardening 



elements of a complete fertilizer, one may proceed as 

 follows: Choose four rows of, say, tomatoes, that run 

 across a typical portion of the field, and withhold from 

 these one of the fertilizer elements, for instance nitrogen. 

 Treat the next four rows the same as the bulk of the field. 

 From the next four rows withhold the potash. Again 

 treat four rows with the usual fertilizer : and withhold 

 the phosphoric acid from the next set of four rows. 



While the test rows are being prepared, a number of 

 strong stakes are made ready to mark off each plot by 

 driving them securely into the ground at the first row of 

 each of the three sets of four rows. If a second dressing 

 of fertilizer is given to the crop, care must be exercised not 

 to apply the element that was withheld when the first 

 dressing was made. In making such a test, it is almost 

 useless to employ only one or two rows, as the plants 

 may draw their supply of the wanting element from the 

 neighboring row. After such a test has been made, the 

 crop from this portion should be measured carefully and 

 compared with that of the neighboring rows. If the first 

 four rows produce a decidedly inferior crop, and the other 

 two sets of four rows are of an average production, it is 

 evident that the field needs nitrogen ; but if only the first 

 and third sets of four rows have fallen off in yield, the field 

 needs nitrogen and phosphoric acid and not potash. 



Another way that has been employed, but one that does 

 not answer the question whether more than one element is 

 deficient, is to use the plots in the way described above ; 

 but in the place of two elements in each, to use only one. 

 For example, choose four rows and fertilize these with a 

 nitrogenous fertilizer only, containing neither potash 



