coastal bermudagrass was highest in cuttings immediately following N
application (Fig. 4.). Fertilizer N was applied in the spring when growth
resumed and again following the second cutting, with each application
supplying one-half of the total amount. We suggest that N be applied to
coastal bermudagrass in four equal applications, with one -application in
spring when growth resumes and one application following each of the first
three cuttings.

 Ammonium nitrogen is oxidized to nitrate nitrogen by microbial activity
when applied to the soil. The resulting chemical reaction increases soil
acidity, thereby lowering soil pH. Since ammonium nitrate contains only half
as much ammonium N per unit of N applied as does ammonium sulfate, we expect
ammonium sulfate to produce twice as much soil acidity per unit of N as
ammonium nitrate. Soil pH in coastal bermudagrass plots ranged from 5.7 with
200 Ib of N/acre as ammonium nitrate to 5.4 with 800 lb of N/acre as ammonium
nitrate in December of 1988 after four annual applications of N, and three
tons of dolomite/acre. However, soil pH ranged from 5.7 to 4.9 with the same
N rates applied as ammonium sulfate (Fig. 5.). Obviously, more lime would be
required if all nitrogen is supplied by ammonium sulfate rather than ammonium
nitrate. But, when ammonium sulfate is used only in amounts to supply sulfur
for coastal bermudagrass soil acidity can be kept in the favorable range with
a nominal liming program. The use of equations in table 1 to calculate the pH
change resulting from the use of 200 Ib of ammonium sulfate per acre and 1200
Ib of ammonium nitrate per acre reveals that soil pH would be reduced by about
0.4 units and most of the reduction would be due to ammonium nitrate (Table
2.). Ammonium sulfate is an excellent source of sulfur for coastal
bermudagrass and it supplies part of the nitrogen.



Table 1. Regression equations for soil-pH versus rate of ammonium sulfate and
 ammonium nitrate on two sampling dates.


Sample Fertilizer
date source Equation C.D.+


June, 1986 I Ammonium Sulfate Y = 5.71-0.00022X 0.508

Dec, 1988++ Ammonium Sulfate Y = 6.01-0.000533X+(7x10- )X2 0.854

June, 19864 Ammonium Nitrate Y = 6.22-0.000285X 0.377

Dec, 1988++ Ammonium Nitrate Y = 5.92-0.000217X 0.724


C.D. = Coefficient of determination.
#Sampled after 2 tons of dolomite/acre in 1984 and 2 annual applications of S
 and N.
"Sampled after 2 tons of dolomite/acre in 1984, 1 ton of dolomite/acre in
 1987 and 4 annual applications of S and N.