Jackson B. Hester 299 



ent amounts to produce over 6 tons of tomatoes per acre, this element 

 is likely to become deficient. Consequently, our fourth problem is that 

 of supplying an adequate amount of boron without producing toxicity. 

 This is done by the use of approximately 10 pounds of borax per acre. 

 (e) Owing to the fact that these soils have been acid so long, much 

 of the native supply of manganese has come into solution and been 

 leached out. Manganese becomes a limiting factor particularly when the 

 soils are limed to an optimum condition for the growth of tomatoes. 

 (/) Fertilizer materials with large amounts of phosphoric acid have 

 been used on these soils for so many years that it is only in exceptional 

 cases that a response from phosphorus is obtained. Some of these soils, 

 in the plowed area, have as much as twenty times the original supply. 



The same problems that occur in the aforementioned sections also 

 occur in New Jersey. However, in the case of boron, response to the 

 application will probably result after a yield of 7 to 8 tons rather than 

 the 6-ton yield previously mentioned. 



When you move into a section like Pennsylvania, however, the situ- 

 ation changes. Instead of calcium and magnesium becoming a limiting 

 factor, phosphorus is the number one problem. This is because the 

 principal crops grown in the past have been grain, corn, and sod crops 

 in which a limited amount of fertilizer has been used. Many of these 

 soils are derived from limestone and, although liming is necessary in 

 many cases, it is not the limiting factor in plant growth. So, owing to 

 the high fixing power of many of the red soils, phosphorus must be 

 added. The second problem is nitrogen and potassium, followed by lime 

 and the minor elements. Boron is the most important minor ele- 

 ment that becomes deficient and it is not likely to show up in the 

 Piedmont belt soils until a yield of 10 or more tons per acre is realized. 

 It might be noted that copper and zinc have not been mentioned. The 

 reason for this is that a spray program to control disease has been in- 

 augurated in which the alternating sprays are a zinc compound and 

 a copper compound. This seems to have been sufficient to take care of 

 these two deficiencies under all conditions. 



Conditions in the Midwest and Canada are like those in Pennsyl- 

 vania: phosphorus is the first limiting factor, and next are nitrogen 

 and potassium. Here again, the yield must be 15 tons of tomatoes 



