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Everglades Station Mimeo Report EES67-12 May 1967
RADISH RESPONSE TO PHOSPHORUS AND
POTASSIUM FERTILIZERS ON EVERGIADS SA
H. W. Burdine and V. UM LIBRARY
IUNI 21 1967
There seems to be little published data on the response of radishes o
fertilizer. Stephens at Gainesville reported a response to nitrogen and potassium
in virgin peat. In a further experiment in the fE t. 0 f Fi6A% signifi-
cant responses were not reported from nitrogen n ad' "tas-z for
crops planted in October, January, and April.
In the Everglades organic soil area, the radish is one of the few vegetable
crops grown for which correlation data of yields, quality, and soil tests used
here have not been obtained. The following data were obtained from a phosphorus
and potassium fertilizer experiment on Everglades Peaty Muck on the Station farm.
Experimental
Fertility levels: Soil samples were taken from each plot just before ferti-
lizer applications were made and the data given is pounds-per acre of phosphorus
and potassium found by our soil testing procedures, shown in Table 1.
Three rates of phosphorus as triplesuperphosphate, and potassium as muriate
of potash were applied in all combinations as follows:
Phosphorus Potassium
Rate 1, P = 20 lbs. P205/Acre Rate 1, K = 20 lbs. K20/Acre
Rate 2, P2 = 100 lbs. P205/Acre Rate 2, K2 = 140 lbs. K20/Acre
Rate 3, P3 = 180 lbs. P205/Acre Rate 3, K3 = 260 lbs. K20/Acre
Soil pH was relatively uniform, averaging 5.70. The single fertilizer
application for all three plantings was made December 16, 1965. The soil was
disked twice and rolled just before each planting.
Soil samples were also taken following each of the three plantings, after
seed germination. Results are given in Tables 2, 3, and 4.
Cultural Practices: Seed of the variety Scarlet Globe Short T op at the rate
of approximately 15 pounds per acre was sown in 6 row beds with rows spaced 9
inches apart on the individual beds. Yield data were obtained from harvesting
three inside rows from each of the two center beds. A total of 90 feet of row
was harvested from each plot. As grower practice leaves space between beds for
machine operations across the field, a factor for an average of 12 inches between
rows was used in calculation of yield data, or 43,560 linear feet of row per acre.
Yield data for the three harvests are calculated on this basis and presented in
Tables 5, 6, and 7.
/ Associate Soils Chemist and Horticulturist, respectively, Everglades Experiment
Station, Belle Glade, Florida.
At each harvest, roots were screened to marketable size, 3/4 to 1-1/4 inches
in diameter. Cracked roots and other culls, due to over or under size, and
elongated roots, were sorted out, counted and/or weighed. These data are presented
as percentages in Tables 9, .10, and 11. Yield data include only marketable roots.
Planting and harvesting dates, and number of days between treatments are as
follows:
Crop
1. 1st planting
2. 2nd planting
3. 3rd planting
Planting Date
12-16-65
2-8-66
3-25-66
Days
Harvest Date
1-17-66
3-12-66
4-22-66
Results
A. Phosphorus and potassium fertility as indicated by soil tests.
Table l.--Soil test results in pounds per
treated later as headed.
acre before fertilization on plots
Phosphorus, pounds per acre Potassium, pounds per acre
K Phosphorus levels K Phosphorus levels
levels P P P levels P1 P2 P3
K1 6 6 5 K1 67 66 70
K2 5 6 6 K2 72 67 72
K3 5 5 6 K3 68 65 72
Soil test results in pounds per acre after fertilization on plots treated as
headed.
Table 2.--First crop, sampled after germination.
Phosphorus, pounds per acre Potassium, pounds per acre
K Phosphorus levels K K Phosphorus levels K
levels P1 P2 P Ave levels P1 P2 P3 Ave
K1 8 12 18 13- K1 65 66 62 64
K2 7 13 20 13 K2 100 102 108 103
S3 6 13 19 13 .. K3 131 143 155 143
P, Ave 7 13 19 P, Ave 99 104 108
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Table 3.--Second crop, samples taken after germination.
Phosphorus, pounds per acre Potassium, pounds per acre
K Phosphorus levels K K Phosphorus levels K
levels Pl P2 P3 Ave levels P, P2 P3 Ave
K 6 12 16 11 K1 54 52 53 53
K 6 11 17 11 K2 84 81 92 86
K3 6 13 -19 13 K3 116 120 130 122
P, Ave 6 12 17 P, Ave 85 84 92
Table 4.--Third crop, soil samples taken after germination.
Phosphorus, pounds per acre : Potassium, pounds per acre
K Phosphorus levels K K Potassium levels K
levels P P2 Ave levels PI P2 P3 Ave
K1 8 14 18 13 K1 41 39 42 41
2 8 13 18 13 K2 63 60 67 64
S8 15 20 14 K3 87 91 107 95
P, Ave 8 14 19 P, Ave 64 63 72
n,
B. Estimated yields in pounds per acre of marketable roots
with varying levels of phosphorus and potassium.
on plots treated
Table 5.--First crop, harvested January 18, 1966.
Potassium Phosphorus levels Potassium
levels P1 P2 P3 Averages
K, 8869 8712 8760 8781
Kg 9087 8869 9269 9075
K3 9148 9244 8966 9119
P, Ave 9035 8939 8998
Yields on this harvest were not'significantly different.
-4-
Table 6.--Second crop, harvested March 15, 1966.
Potassium Phosphorus levels Potassium
levels P P2 P Averages
K10,200 10,031 10,539 10,257
K2 11,176 11,394 11,568 11,379
K3 11,047 11,749 12,209 11,668
P, Ave 10,808 11,058 11,438
Yield differences were highly significant for effects of
potassium.
both phosphorus and
Table 7.--Third crop, harvested April 26, 1966.
Potassium Phosphorus levels Potassium
levels P1 P2 P3 Averages
K.1 10,055 8,906 10,140 9,701
K2 11,435 12,197 12,173 11,935
K3 11,737 13,976 13,729 13,147
P, Ave 11,076 11,693 12,014
Yield differences were highly significant for effects of
potassium.
both phosphorus and
Table 8.--Estimated pounds of phosphorus and potassium per acre removed by the
first crop. (Based on total pounds of roots removed, percent dry
weight, and phosphorus and potassium content of root samples.)
Phosphorus, pounds per.acre Potassium, pounds per acre
K Phosphorus level K K Phosphorus level K
levels P1 P2 P2 Ave levels P P P Ave
K1 2.2 2.4 2.3 2.3 K1 29.0 26.2 27.3 27.5
K2 2.1 2.3 2.3 2.2 K2 32.2 29.4 30.5 30.7
K3 2.2 2.3 2.2 2.2 K 31.8 32.1 30.4 31.4
P, Ave 2.2 2.3 2.3 P, Ave 31.0 29.2 29.7
(Differences highly significant)
(Differences are significant)
-5-
Table 9.--Estimated pounds of phosphorus and potassium per acre removed by the
third crop. (Same calculation basis as Table 8.)
Phosphorus, pounds per acre Potassium, pounds per acre
K Phosphorus level K K Phosphorus level K
levels P P P Ave levels P P P Ave
1 2 3 1 2 3
K1 2.3 2.5 2.9 2.6 K1 23.9 20.8 24.5 23.1
K2 2.5 3.0 3.2 2.9 K2 32.3 34.5 35.1 34.0
K3 2.4 3.2 3.4 3.0 K3 39.3 46.8 48.9 45.0
P, Ave 2.4 2.9 3.2 P, Ave 31.8 34.0 36.2
(Differences highly significant) (Differences highly significant)
(The second crop was not sampled for chemical analysis.)
C. Percentage culls (total weight basis) for roots out of size and percent culls
from all discarding criteria.
Table 10.--First harvest.
Culls, out of size, percent Culls, total, percent
K Phosphorus level K K Phosphorus level K
levels P1 P P Ave levels P1 P P3 Ave
K1 4.8 4.1 4.5 4.5 K, 8.3 7.9 8.5 8.2
K2 4.4 4.8 4.4 4.5 K2 9.0 9.1 7.8 8.6
K3 3.5 3.5 3.8 3.6 K3 8.5 7.8 9.1 8.5
P, Ave 4.2 4.1 4.2 P, Ave 8.6 8.3 8.5
(Differences not significant) (Differences not significant)
Table 11.--Second harvest.
Culls, out of size, percent Culls, total, percent
K Phosphorus level K K Phosphorus level
levels P P P Ave levels P P2 P3 Ave
K1 6.7 6.9 5.6 6.4 K1 14.1 12.3 10.7 13.3
K2 6.0 5.5 4.9 5.5 K2 13.4 11.5 13.0 12.6
5.8 5.2 4.2 5.1 K3 13.8 14.0 11.4 13.1
P, Ave 6.2 5.9 4.9 P, Ave 13.8 12.6 11.7
(Significant decrease with P and K)
(Significant decrease with P)
Table 12.--Third harvest.
Culls, out of size,.percent -. Culls, total, percent
K Phosphorus level K K Phosphorus level K
levels P P P Ave levels P P P Ave
K1 5.0 6.9 5.9 5.9 K1 7.8 9.6 8.0 8.5
K2 5.0 4.5 4.0 4.5 K2 7.4 6.9 6.7 7.0
K3 3.7 3.3 5.2 4.1 K3 9.4 5.6 9.0 8.0
P, Ave 4.6 4.9 5.0 P, Ave 8.2 7.4 7.9
(K and PK interactions significant)
(K.and PK interactions significant)
Conclusions
1. Yields of the first crop, sown December 16 and harvested January 17 were
obviously limited by some factor not included as a variable in the experiment.
It is believed that this may have been nitrogen. Higher yields of the third
crop over the second crop indicates a limiting factor for the second crop also.
Nitrogen cannot be ruled.out as a limiting factor for the second crop also,
although it was not expected.
2. For maximum yields and quality of three consecutive radish crops, pending
further experiments, it isbelieved that.the Everglades Experiment Station soil
tests should.show about 12 pounds of phosphorus and 150 lbs. of potassium per
acre after fertilization.
3. Soil tests results given in Table 4, indicate that the highest yields and
quality of other vegetable crops would not be obtained without additional
fertilization following three radish crops started at the above suggested
fertility level.
EES67-12
400 copies
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