cows, which are about 8% and 54% of the dry mat-
ter, respectively (National Research Council, 1984).

Fertilization effect on minerals in bahiagrass
 Fertilization with P205 and K20 increased P and
K content of bahiagrass regrowth forage, and the
degree of increase was related to the amount of P205
and K2O applied (Table 3, Appendix Table 2A).
 Dietary P levels recommended by the National
Research Council (1984) for the types of beef cattle
grazing in Florida range from 0.18% of the dry
matter for dry cows to 0.23% of the dry matter for
lactating cows of average milking ability (most
Florida brood cows), and to 0.29% of the dry matter
for lactating cows with superior milking ability.
Phosphorus levels in regrowth forage were highest
in 1987 (Table 3). Only one site had average P levels
below that recommended for most beef cattle and
that was in treatments not fertilized with P205.
Levels of P in bahiagrass were lowest in 1988, and
average P levels of treatments not receiving P20O at
two sites were slightly below that required by most
lactating cows.
 The P content in available forage was lower than
the P content in regrowth forage (Figure 5). The P
level was particularly low in available forage in the
fall and winter. These levels would cause P defi-
ciency in lactating brood cows not supplemented
with P. A deficiency in P could have a negative
effect in rebreeding.


S% Phosphorus


May Jun JUI
 S *Regrowth' Fo


Figure 5. Phosphorus conte
 bahiagrass forage
 ranches in south F
 fertilizer treatment


1989




L


for Florida (Cunha et al., 1964) would satisfy the P
needs of cattle, and would be more economical than
fertilizing bahiagrass to provide P nutrition for
cattle.
 The National Research Council (1984) recom-
mends a dietary K level for beef cattle of 0.5 to 0.7%
of the dry matter. Bahiagrass K levels were below
this range at several sites in 1988. Other minerals
were present in bahiagrass forage in adequate
amounts as recommended by the National Re-
search Council, with the exception of Cu. The
National Research Council recommends that cattle
diets contain 4 to 10 ppm of Cu. Forage copper
levels were at or below the lower end of this range
in many cases. Possibilities of a Cu deficiency for
cattle grazing Florida pastures has long been
recognized, so the addition of this element to the
mineral supplement is recommended routinely
(Cunha et al., 1964).

Soil analyses from demonstration sites
 Soil P values were very low (< 10 ppm) to low (10
to 15 ppm) at seven sites and medium (16 to 30
ppm) at only one site (Table 4). Soil K values were
very low (< 20 ppm) to low (20 to 35 ppm) at five
sites, medium (36 to 60 ppm) at two sites and high
(61 to 125 ppm) at only one site. All soil parameters
were variable among sites and with there being no
obvious relationships between any parameter and
bahiagrass yield. Fertilization treatment also had
no effect on any soil parameters. These data
indicate that soil testing as now commonly used to
manage the fertilization of Florida bahiagrass
pastures is of limited value. This could be because
soil test data and plant response relationships were
developed with annual crops and bahiagrass is a
deep-rooted perennial plant.


 Fertilizer recommendations for established
 bahiagrass
 From data developed in this field study in
 Aug Sep Oct Nov Dec conjunction with other data from the literature, the
 rage AvailabeForagefollowing recommendations are presented for
 rage Available" Forage
 fertilizing established bahiagrass pasture in
int in regrowth and available Florida. These recommendations support revised
by month averaged over eight University of Florida, IFAS recommendations
-lorida (one year average over all (Kidder et al., 1990)
). (Kidder et al., 1990).


 Although a mineral supplement containing P is
recommended for all grazing cattle in Florida,
mineral supplementation would be more critical if
pastures are not fertilized with P20.5 A mineral
supplement similar to one commonly recommended


1. With the annual application of 60 lb or less N/A
 of bahiagrass pasture, do not apply any P205 and
 K20 for at least 3 years. The field study is
 continuing (1990) and future recommendations
 of 60 lb/A of N only may be extended to periods
 longer than 3 years.