Title: Vegetarian
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Permanent Link: http://ufdc.ufl.edu/UF00087399/00063
 Material Information
Title: Vegetarian
Series Title: Vegetarian
Physical Description: Serial
Creator: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: November 1969
 Record Information
Bibliographic ID: UF00087399
Volume ID: VID00063
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.

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,- I V._ i ,I. it/--% /-*%:;i ~,i L_- *- *. "i&s I C"INi.
UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIEN


4,)~


Vegetable Crops Department

V#Gi3E VAEIR A


CES


fj^Tj L

4- -^^<_7


George A. Marlowe, Jr.
Chairman

Mason E. Marvel
Associate Vegetable Crops Specialist


James Montelaro
Vegetable Crops Specialist

James M. Stephens
Assistant Vegetable Crops Specialist


November 18, 1969


TO: COUNTY AGRICULTURAL AGENTS

NO: 86

IN THIS ISSUE


Drop in pH from Summer to Winter
Use of Low Salt Index Fertilizers in Vegetable Production


I. Drop in pH from Summer to Winter

Vegetable growers in Florida should be aware of a possible drop in
soil pH from summer or early fall to winter. if this possibility is not
taken into consideration, the result can be costly to the producer. In most
cases, the drop in pH is quite small-ranging only from 0.1 to 0.3 units.
However, the drop can be considerably more under certain conditions. A
change of up to 0.8 of a unit has been observed on many occasions on both
sandy and organic soils,

The problem that develops following such a change is simply an
imbalance in nutrition. Quite often, a deficiency of one or more of the
minor elements becomes evident. The problem is considerably harder to se've
during tha growth of the crop than it would be if measures were taken before
the crop is planted.

Soil scientists explain the drop in soil pH on the basis of: (1) n
reduction of the active lime, (2) production of acids and (3) a change in
the colloidal complex resulting from the decomposition of humus in the soil.

To co;;s.nsate for a drop in pH, a soil can be limed slightly heavier
;.an r:omal providing that the amount of minor element applied is also
increased. Another alternative is the use of base-forming or low-acid
forming fertilizer materials. Calcium nitrate is an example of a base-forming
fertilizer source. On the opposite end of the scale is ammonium sulfate-an
acid forming material.








-2-


2. Use of Low Salt Index Fertilizers in Vegetable Production

Vegetable crops in many of the more important production areas in
Florida are subject to injury from excessive soluble salts on occasions.
This,is especially true where growers use large amounts of fertilizer
together with irrigation water that is high in soluble salts. The problem
is most severe following drought periods. Growers should be aware of this
potential problem and make every effort possible to keep soluble salts to a
minimum consistent with good, economical production practices.

One practice that is not being used to the fullest extent is to
keep total soluble salts down In vegetable production by the use of "low
silt-index fertilizer materials."* They can be used to formulate the
primary fertilizer application used before, during or after seeding or
transplanting. They can also be used as sources for sidedressing materials.
Low salt-index materials do not increase the cost of fertilizer significantly.

This is clearly pointed out in the tables that follow which were
prepared by Dr. D. R. Hensel, Soils Chemist in Charge, Potato investigations
Laboratory, Hastings, Florida. They are reprinted here with Dr. Hensel'-
permission. The information was presented at grower meetings held at
Hastings and Bunnell, Florida, where salt problems are quite common. The
information in these tables should be carefully studied by everyone involved
in the fertilization of vegetable crops in Florida.


*Salt Index (definition) Fertilizers increase the
salt concentration of the soil solution. The salt index
of a fertilizer is a measure of this phenomenon and is
determined by placing the material u;der study in the
soil and measuring the osmotic pressure of the soil solu-
tion. Osmotic pressure is expressed in atmospheres. Salt
index is actually the ratio of the increase in osmotic
pressure produced by the material in question to that pro-
duced by the same weight of sodium nitrate, based on a
relative value of 100.













TABLE 1

SALT INDEXES OF SELECTED FERTILIZER MATERIALS
SALT INDEX PER UNIT OF:


MATER I ALS

NITROGEN SOURCES

Sodium Nitrate 16.5%N

Ammonium Nitrate 35. O%N

Ammonium Sulfate 21.2%N

Nitrate of Soda Potash 15%N, 14%K20

Calcium Nitrate 11.9%.N

Urea 46.6%N

Natural Organics 5%N

PHOSPHORUS SOURCES

Regular Superphosphate 20%P205

Concentrated Superphosphate 45%P205

Monoammonium Phosphate 12.2%N, 61.T/%P205

Diammonium Phosphate 21.2%N, 53. 8%P205

POTASSIUM SOURCES

Potassium Chloride 60%K20

Potassium Nitrate 13.8%N, 46.6%K20

Potass i um Sul fate 5L-'.,20

Sulfate of Potash Magnesia 21.9y/K20


RAd MATERIAL PRIMARY NUTRIENTS-


100

49

54

51

73

27

16


100

105

69

92

52

75

4



8

10

30

34



116

74

46

43


Prepared by Dr. D. R. Hensel, Potato Investigations Laboratory, Hastings,
Florida.













TABLE II

TOTAL SALT If:;EXES OF VARIOUS MATERIALS PROVIDING
40 LBS NITROGEN AND 40 LBS K20
: : ,,, ,,


MATER AL A

Sodium Nitrate

Potassium Chloride


So d um N i tr'ate

Potassium Sulfata


Nitrate of Soda Potash

Potassium Chloride


Nitratr of Soda Potash

Potassium Sulfate


Calcium Nitrate

Potassium Sulfate


Am:zon i um N i trate

Potessium Nitrate


Urea

Potassium Nitrate


Prepared by Dr. D. R.
Hastings, Florida.


H3nsel, Potato Investigations


Laboratory,


ANALYSIS

16.5%N

60%K20


16.5%N

54%K 20


15-0-14

60%K2 0


15-0-14

54%K20


11.9% I

54%K20


33.5%N

13-0-44


45%N

13-0-44


LBS

242

67
309

242

74
316

266

5
271

266

5
271

336

74


87

91


63


154


UNITS

2.0

2.0


2.0

2.0
.T.o

3.9

.1
4.0

3.9

.1
*.0

2.0

2.0
V..o

1,.4

2.6
4.0

1.4

2.6
470


SALT INDEX
UNIT TOTAL

100 200

32 64


100 200

14 28
228

51 200

32 3
203

51 200

14 1
201

73 146

14 28
T74

49 69

20 52


27 38

20 52
90


--- -













TABLE ilI

SUMx;ARY OF SEVERAL MATERIALS PROVIDING 40


LBS N AND 40 LBS K20


MATERIAL

Sodium Nitrate &
Potassium Chic

Sodium Nitrate &
Potassium Sulf

Nitrats of Soda P
Potassium Sulf

Calcium Nitrate &
Potz.s i umr Sulf

Ammonium Nitrate
Potassium Nitr

Ammonium Nitrate
Potassium Chic

Ammon i U,- N i t i'a te
Potassium Sulf

Urea, Ammonium Ni
Potassium Nitr

Urea & Potassium
Nitrate

Urea & Potassium
Su: 7,le

Urea & Potassium
Chloride


Prepared by
Florida.


LBS OF SALT APPROX.
MATERIAL INDEX COST

$
ride 309 264 8.90


fate 316 228 9.60

'otash &
ate 221 201 9.00


fate 332 188 10.30


ate 178 121 6.90

&
>ride 187 162 4.80

&
ate 194 126 5.60

rate &
ate 166 108 7.10


154 90 7.60


153 82 6.70


156 118 5.90


Dr. D. R. Hensel, Potato Investigations


%
N03-N


100


100


100


100


65


50


50


50


30


0


0


Laboratory,


*


Sincere;y,


James Montelaro
Vegetable Crcps Specialist


LBS
CHLOR I NE


35


0


0


0


0


35


0


0





0


35


Hastings,




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