Two 4 x 8 ft wire cattle-exclusion cages were
placed on each 50 x 100 ft treatment area in March.
Cages were positioned on an area where the
bahiagrass had been previously staged to a 2-inch
stubble height, if needed, with a plot harvester.
Forage from a 20-sq-ft area inside and outside each
cage was harvested to a 2-inch stubble every 30 to
60 days from April or May through December. On
each harvest date, each cage was moved to a
pasture area harvested outside that cage, thus
cages were moved around the 50 x 100 ft treatment
areas throughout the year.
 Total fresh forage harvested inside and outside
each cage was weighed and sampled for analysis.
Dry matter content was determined on samples
dried in a forced-air dryer at 60C. Dry matter
yield was calculated from fresh weight data and dry
matter content. Crude protein content and total
digestible nutrients (TDN) were determined with a
near-infrared analyzer. Forage samples were
ashed at 6000C and acid digested to determine P, K,
Ca, Mg, Zn, Mn, Cu and iron (Fe).
 The field study was initiated in March 1987 and
completed in December 1989.

Forage yields and additional production cost
 Two important terms are used in this publication
to describe the type of forage harvested during the
study. Regrowth forage is bahiagrass harvested
inside an animal exclusion cage which had grown
from a 2-inch stubble since the last harvest. Avail-
able forage is bahiagrass harvested outside the
cage and is forage actually available to the grazing
animal. Yield data were obtained from regrowth
harvests.
 There was a consistent increase in forage yield to
60 lb of N/A applied in March over the no fertilizer
treatment (Table 1, Appendix Table 1A). Over
three years the treatment receiving 60 lb N/A
averaged 1,760 lb more dry matter per acre annu-
ally than the treatment receiving no fertilizer. It
presently costs about $20/A to apply 60 lb of N,
including $4 per acre spreading cost. This expense
appears justifiable, costing about $23 for each ton
of additional dry forage produced (Table 2).
 In comparison to 60 lb of N/A only, a positive
response in dry matter yield was obtained when 45
lb of P205 and 45 lb of K20/A were applied in March
along with 60 lb of N/A (Table 1). However, the
increased production was only 400 lb of dry forage
per acre annually. It costs about $14/A for the P2,O
and K20 and approximately $72 for each additional
ton of dry forage produced.


 Applying 60 lb of N/A in March and then again
in September produced an average of 480 lb more
dry matter per acre than one 60 lb N application in
March (Table 1). It would cost about $20/A for the
second N application, and the cost for each addi-
tional ton of dry forage would be about $84 (Table
2). Several research studies have shown a linear
response in dry matter yield of bahiagrass to
increasing rates of N fertilization, even when N
was applied as split applications (Blue, 1966; Blue
and Graetz, 1977). However, these studies did not
evaluate a situation in which one half of the N was
applied as a second application as late as Septem-
ber, a practice used on some ranches in Florida
because of heavy summer rains.
 In comparison to two applications of 60 lb N/A, a
positive response was obtained in dry matter yield
with the addition of 90 lb of P205 in March, and 90
lb/A of O20 equally split between March and
September, along with 120 lb of N (Table 1). The
increased yield averaged 700 lb more dry forage per
acre annually than the 120 lb of N/A alone. It
presently costs about $29/A for the P205 and K20
applied, thus costing approximately $82 for each
additional ton of dry forage produced.

Effect of N on bahiagrass growth distribution
 Increased yield due to the application of N in
March was immediate, and continued throughout
the summer period (Figure 1). Early spring growth
of pasture forage is important because of low forage
availability after the winter months, and demands
by cows which are usually nursing calves and being
rebred. Typical low spring rainfall was experienced
in all three years of this field study, and yet sub-
stantial responses in forage growth and forage
quality to N fertilization were obtained both in
April and in May. This points out the importance
of applying N fertilizer to bahiagrass pasture as
early as February or March.
 The response to N application in September was
also immediate but limited only to the September
or October harvests. Forage growth in general was
reduced after October, because of shorter days, so a
response to N fertilization might not be expected.
The results of this field study document the poor
response of bahiagrass to N applied in September,
and suggest that N should be applied to bahiagrass
as a single application in the spring, but if split, the
second application should be well before Septem-
ber. Research data developed previously at
Gainesville (Blue, 1966; Blue and Graetz, 1977)
support this conclusion.