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 Everglades Station Mimeo Report EES68-9 May 1968


 Some.Soil pH Effects on Soil Tests and Growth of
 Some Vegetable Crops on Everglades Organic Soil
 1/
 H. W. Burdine and V. L. Guzman-


 The pH of our organic soils is one of the most important soil test deter-
 minations made for planning treatments and cropping procedures that must be
 followed for maximum yield and quality of vegetable crops. It has been com-
 pared to taking the temperature of a patient by a physician. It affects the
 solubility or availability of plant food elements to plants. As the reaction
 goes down from pH 7, the condition is more acid, as it goes up from 7, it is
 more alkaline. The most favorable soil reaction for most vegetable crops seems
 to be on moderately acid soil, about pH 5.8. Within the normal ranges found on
 the organic soils, availability of calcium, phosphorus and manganese are most
 affected, with the latter most frequently affecting plant growth. However, as
 will be shown further in this report, not all crops or even varieties within
 the same crop will respond to pH for the same reason, nor is the same pH
 mentioned above most favorable for all crops under the same specific conditions.

 A. Changes in soil reaction:

 The following data taken from experiments conducted over a period of years
 indicates that soil reaction is not constant and pH tends to drop following
 fertilization and crop growth. It is assumed, but not established, to return
 more or less to its original level during the summer fallow period unless
 flooded. The purpose of the following table is only to show that pH may not
 remain constant, but probably drops under crop growth. The second samplings
 were mostly taken before fertilization, but not all. The third samplings were
 mostly taken at the end of experiments, but not all.

 Table 1. pH differences from the same plot areas during experiments.

 Plot Before Plowing Second Sampling Third Sampling
 No. Date pH Date pH Date pH
 *1. Sept. 1 7.26 Sept. 18 7.25 Nov. 3 6.51
 2. Jan. 12 6.58 Feb. 6 6.50 March 17 6.01
 3. Nov. 10 6.63 Dec. 2 6.52 Jan. 19 6.39
 4. Nov. 3 6.70 Dec. 10 6.27 March 16 6.28
 5. Jan. 19 6.72 Feb. 10 6.38 May 15 6.24
 6. Sept. 24 6.48 Oct. 18 6.43 Dec. 23 6.03
 *7. Nov. 28 7.00 Jan. 6 6.41 March 19 6.24
 *8. Dec. 10 7.00 Jan. 2 7.00 April 3 6.63

 Fields previously flooded.


 / Associate Soils Chemist and Horticulturist, respectively, Everglades
 Experiment Station, Belle Glade, Florida.