BIG BEND HORTICULTURAL LABORATORY ,
March 21, 1966 /i
Big Bend Hort. Lab. Mimeo Report BBL66-2
THE EFFECT OF NITROGEN FERTILIZATION ON THE YI
OF MONEYMAKER AND MOORE PECANS IN NORTH FLORIDA.
by H. W. YOUNG and H. H. BRYAN
An experiment was initiated in 1960 at the North Florida Experiment
Station, Quincy, Florida in a pecan orchard that was planted in the early
1930's and consisted of 100 Moneymaker and 91 Moore trees spaced 50 feet
apart. The two objectives of this experiment were: (1) to determine the
effect of nitrogen, zinc and pest control, and (2) to rejuvenate a run
down orchard. The orchard had been used for many years to evaluate disease
controls, but it was recorded that for the eight years proceeding 1960, the
nut production was practically non-existent.
The results reported here are for the period 1960 through 1965.
During this period Phosphorus and Potassium was supplied each year by the
addition of 500 pounds per acre of 0-10-10. Soil tests indicated that
Calcium, Magnesium, Phosphorus and Potassium levels were high and the pH
was about 6.5. Clover and native grass were maintained in the orchard
which was used for cattle pasture periodically throughout the year. The
pasture was mowed short to facilitate harvesting.
Ammonium nitrate was applied each year before growth started. The
rates used, expressed in pounds of nitrogen per acre, were 0, 56 and 122
each year from 1962 through 1965. In 1961 the rates were 0, 18 and 36.
Because it was the intent to gradually rejuvenate the entire orchard an
individual tree did not necessarily receive the same rate of nitrogen each
Table 1 presents the yields in pounds of nuts per tree of Moneymaker
and Moore pecans which had been treated with the three rates of nitrogen.
It must be kept in mind that the clover provided an additional source of
nitrogen. In the same year the nitrogen was applied the two rates of
nitrogen applied did not greatly increase the yield of nuts, however,
the trend was consistent. When 56 or 112 pounds of nitrogen was applied
the yield of nuts was increased slightly regardless of nitrogen appli-
cation in previous years.
1Associate Horticulturist and Head, Big Bend Horticultural Laboratory,
Monticello, Florida, and Assistant Horticulturist, North Florida
Experiment Station, Quincy, Florida, respectively.
Table 2 is perhaps more significant. This table presents four year
yields of Moneymaker and Moore pecan trees treated with three rates of
nitrogen from 1961 through 1965. The figure for the average nitrogen ap-
plied in pounds per acre for the five years was obtained by totaling all
the nitrogen applied to each tree. The totals were then grouped (on a
per acre basis) in 100 pound increments and the mean shown in table 2.
For example, those trees shown as receiving 50 pounds of nitrogen per
acre received between 0 and 100 pounds of nitrogen per acre over the five
year period. The trend for both varieties indicated with a clover cover
an additional 60 pounds of nitrogen per acre seemed optimum insofar as
yield was concerned.
The total yields per tree obtained, as well as nut quality improve-
ment, was not as rapid as might be desired, however, it should be consid-
ered that these trees had been in a neglected condition for a number of
years and had reached the size where competition for soil moisture was
acute. In 1961 and 1962 some of the trees were sprayed for pest control
and others were not sprayed. In results reported here this was not con-
sidered, even though spraying did increase yields considerably.
Distinct relationship between zinc and nitrogen applications did
not exist in this experiment. However, it was interesting to note the
different responses of the two varieties to zinc applications made in
1960. Table 3 gives the yields in pounds per tree of pecans treated
in 1960 with 0, 2 and 4 pounds of Zinc Sulphate per tree. The Money-
maker variety, regardless of nitrogen applications, consistently gave
higher yields where the 4 pounds of zinc sulphate was used. On the
other hand, the Moore variety yielded the highest in three of the four
years where zinc sulphate had not been applied.
TABLE 1. YIELDS IN POUNDS OF NUTS PER TREE OF M'CiEYM'IAKER AND
MOORE PECANS TREATED VITH THPEE RATES OF NITROGEN.
Rate of Nitrogen applied per acre (2)
1961 i oneymaker (1)
No yield data
(1) In brackets, number of trees from which data was taken.
(2) Rates of Nitrogen in pounds per acre.
1.- 56 in every year except 1961 when 18 was applied.
2.- 112 in every year except 1961 when 36 was applied.
THE EFFECT OF NITROGEN FERTILIZATION ON THE YIELD
OF MONEYMAKER AND MOORE PECANS IiN NOPTH FLORIDA.
by H. Vi. YOUNG AND H. h. BYAN
TABLE 2. FOUR YEAR YIELDS OF iO,1EYE~AKER AND i:OORE PECANS
TREATED WITH THREF RATES OF NITROGEN FROM 1961
THROUGH 1965. (NO YILLD RECORDS FOR 1964).
Average Nitrogen applied
in pounds per acre for
Total four year yield of nuts
in pounds per tree".
* In brackets, number of trees included in data.
TABLE 3. YIELD IN POUNDS OF NUTS PER TREE OF PECANS
TREATED IN 1960 WITH THREE RATES OF ZINC
Pounds of Zinc Sulphate applied
iloore 1961 50.6 (3) 32.2 (47) 30.8 (10)
1962 27.2 (3) 18.5 (47) 10.7 (10)
1963 24.4 (3) 20.0 (47) 19.1 (10)
1965 21.4 (3) 21,9 (47) 21.2 (10)
* In brackets, number of trees included in data.