Title: Liming and fertilization of potatoes
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Title: Liming and fertilization of potatoes
Physical Description: Book
Creator: Myhre, Donald L.
Publisher: Potato Investigations Laboratory,
Copyright Date: 1959
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Bibliographic ID: UF00076258
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
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Resource Identifier: 137240325 - OCLC

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POTATO INVESTIGATIONS LABORATORY
Hastings, Florida

Mimeo Report 59-6(Revised) September 25, 1959


LIMING AND FERTILIZATION OF POTATOES
Donald L. Iyhre

Need for Liming
Most virgin and cultivated sandy soils in the Hastings area are naturally acid,
due to the nature of the parent material from which they are formed and also to the
soil-forming process in the humid climate which leached out the basic elements such
as sodium, potassium, calcium and magnesium. Periodic liming as indicated by a pH
test is necessary to replace the calcium and magnesium taken up by the potato crop
and lost by leaching, neutralize the acidifying effect of fertilizers, make the
nutrients in the soil and fertilizer more available to the plants, reduce the leach-
ing loss of ammonical nitrogen by heavy rains, make aluminum more unavailable, and
improve structure of soil. Liming also increases nitrification which is a precau-
tionary measure against nutritional leaf roll of potatoes.

Soil Sampling
Soil samples for pH determinations in indicating liming requirements should be
collected on old land in the fall immediately after the summer cover crop has been
turned under and on new land as soon as the land has been cleared and leveled but
before the cover crop is planted. However, if nutritional leaf roll has occurred in
potatoes grown on old land, the soil should be sampled in the spring soon after the
potatoes have been dug. In all cases, lime should be applied as soon as possible
after the soil samples have been collected and the pH determined in order to provide
additional time for the lime to react.
It is extremely important to obtain a representative soil sample from the field
being sampled. A tube, auger, or spade may be used to collect the sample. Each
type of soil should be sampled separately by taking from eight to ten plugs or
slices of the surface six inches over the area and mixing them together to make one
sample. Several such samples should be taken from each field, usually about one or
two per ten acres.

Soil Acidity (pH)
A soil pH of 5.5 is currently recommended for growing potatoes in the Hastings
section. Potatoes will grow at a higher pH than is recommended for them, but gen-
erally scab is less troublesome in acid soils below pH 5.5. A pH of 6.0 or higher
should be avoided because certain microelements such as boron, copper, manganese and
zinc become less available on most soils at high pH levels. For average sandy soils
lime may be used on the basis of 200 pounds per acre of ground limestone (dolomite
or high calcic limestone) or 120 pounds per acre of hydrated lime for each 0.1 pH
below 5.5.

Kind of Lime
Dolomite is preferred for general use to maintain proper soil pH for potatoes
because of the magnesium it contains. High calcic limestone is preferred where more
rapid correction of acidity is desirable. Hydrated lime gives still faster correc-
tion of acidity but is more costly and difficult to use. It may be used in emergen-
cies where liming of new lands or those subject to leaf roll has been delayed until
late fall.


1 f






Amount of Fertilizer
About 2,500 pounds per acre of 6-8-3 fertilizer applied in bands is currently
recommended for growing potatoes in the Hastings area. Proportionately less of
higher analysis material can be used. For example, 2,200 pounds of 7-9-9 contains
approximately the same amount of plant nutrients as 2,500 pounds of 6-8-8 and is
usually cheaper per unit of plant nutrient.

Contents of Fertilizer
1. Nitrate Nitrogen.- For average conditions, one-fifth of the nitrogen should
be nitrate nitrogen. The fertilizer tag would then show 1.2 percent nitrate nitro-
gen in a 6-8-8 fertilizer, or 1.4 percent in a 7-9-9 fertilizer. For new lands or
where nutritional leaf roll has been prevalent, the nitrate can be increased up to
one-third of the total nitrogen present.
2. Insoluble Nitrogen.- Generally, the use of more than one unit of nitrogen
from insoluble sources can not be economically justified for fertilizers used in
production of potatoes. Research in South Florida on soils similar to some in the
Hastings area indicates that the use of organic nitrogen, which is relatively costly
from natural organic, did not increase yields in any of the last four years com-
pared to inorganic nitrogen.
3. Potash and Chlorides.- Not more than one-half of the potash should be de-
rived from muriate (chloride) of potash, but the lower the better if harvest is to
be delayed beyond the average digging dates or if a dry season is encountered.
4. Magnesium.- The fertilizer should contain 2 percent soluble magnesia (MgO).

Fertilizer Sidedressing
Recommendation for Prevention of Nutritional Leaf Roll.- New lands or ones pre-
viously showing leaf roll should be sidedressed with about 150 pounds of nitrate of
soda, or its equivalent per acre at about 40 days after planting.
Recommendation at Present for Light and Dark Sandy Soils.- Results of tests
from 1947 to 1955 indicate that yield of potatoes on the lighter sandy soils may be
increased by a sidedressing supplying about 30 pounds of nitrogen per acre applied
about 40 days after planting. A similar sidedressing on dark sandy soils is un-
likely to prove beneficial unless excessive rainfall occurs early in the growing
season. Foliar sprays containing nitrogen, phosphorus and potassium are not recom-
mended at this time for potato production.
Recent Information.- Results from experiments during the last three years show
that potato yields were increased by a sidedressing application of 30 pounds of
nitrogen per acre, generally regardless of the source of nitrogen: ammonium nitrate,
6-8-8, 7-9-9, 10-0-10, urea, nitrate of soda, or nitrate of soda-potash. This sup-
plemental nitrogen was in addition to about 150 pounds of nitrogen per acre applied
in bands at planting. Based on these somewhat preliminary results ammonium nitrate
was usually the most economical sidedressing material for potatoes. However, addi-
tional studies will have to be made before the most economical sidedressing material
and method can be recommended for potato crops grown on soils that vary in texture,
organic matter, fertility and moisture.

References
1. Hayslip, N.C. and Howard W. Burdine. Results of potato fertilizer experiments in
the Indiantown and Palm City area. Fla. Agr. Exp. Sta. Indian River
Field Lab. Mimeo Rpt. 59-3. April 28, 1959.
2. McCubbin, E.N., D.L. Iyhre and G.M. Volk. Effects of sidedressing and foliar-
nutritional spray on yield of potatoes at Hastings, Florida. Fla. State
Hort. Soc. Proc. 68: 216-220. 1955.
3. Volk, G.M. and Nathan Gammon, Jr. Effect of liming and fertilization on yield
and correlation of nutritional leaf-roll of Irish potatoes, Fla. Agr.
Exp. Sta. Bul. 504. 1952.
4. Volk, Gaylord M. The value of organic nitrogen in vegetable fertilizers. Fla.
State Hort. Soc. Proc. 67: 153-157. 1954.
300 copies







V) POTATO INVESTIGATIONS LABORATORY
Hastings, Florida

Mimeo Report 59-6 October 1, 1958

LIMING AND FERTILIZATION OF POTATOES1
Donald L. Myhre

Most virgin and cultivated sandy soils in the Hastings section are natu-
rally acid, due to the nature of the parent material from which they were
formed and also to the soil-forming process in the humid climate which leached
out the basic elements such as sodium, potassium, calcium and magnesium. Peri-
odic liming as indicated by a pH test is necessary to replace the calcium and
magnesium taken up by the potato crop and lost by leaching, neutralize the
acidifying effect of fertilizers, make the nutrients in the soil and fertilizer
more available to the plants, and make aluminum more unavailable. Liming also
increases nitrification which is a precautionary measure against nutritional
leaf roll of potatoes.

Soil Sampling.- Soil samples for pH determinations in indicating liming re-
quirements should be collected on old land in the fall immediately after the
summer cover crop has been turned under and on new land as soon as the land has
been cleared and leveled but before the cover crop is planted. However, if
nutritional leaf roll has occurred in potatoes grown on old land, the soil
should be sampled in the spring soon after the potatoes have been dug. In
all cases, lime should be applied as soon as possible after the soil samples
have been collected and the pH determined in order to provide additional time
for the lime to react.
It is extremely important to obtain a representative soil sample from the
field being sampled. A tube, auger, or spade may be used to collect the sample.
Each type of soil should be sampled separately by taking from eight to ten plugs
or slices of the surface six inches over the area and mixing them together to
make one sample. Several such samples should be taken from each field, usually
about one or two per ten acres.

Soil Acidity (pH).- A soil pH of 5.5 is currently recommended for growing
potatoes in the Hastings section. Potatoes will grow at a higher pH than is re-
commended for them, but generally scab is less troublesome in acid soils below
pH 5.5. A pH of 6.0 or higher should be avoided because certain microelements
such as boron, copper, manganese and zinc become less available on most soils at
high pH levels. For average sandy soils lime may be used on the basis of 200
pounds per acre of ground limestone (dolomite or high calcic limestone) or 120
pounds per acre of hydrated lime for each 0.1 pH below 5.5, as shown in Table 1.

Kind of Lime.- Dolomite is preferred for general use to maintain proper
soil pH for potatoes because of the magnesium it contains. High calcic lime-
stone is preferred where more rapid correction of acidity is desirable.
Hydrated lime gives still faster correction of acidity but is more costly and
difficult to use. It may be used in emergencies where liming of new lands or
those subject to leaf roll has been delayed until late fall.


1Revision of Mimeo Report 58-6









TABLE 1.- Amount of Lime Required to Adjust Soil pH to 5.5.

Original Pounds per Acre Lime Required to
Soil pH Adjust Soil pH to 5.5
Dolomite or High Calcic Hydrated
4.3 2400 1440
4.4 2200 1320
4.5 2000 1200
4.6 1800 1080
4.7 1600 960
4.8 1400 840
4.9 1200 720
5.0 1000 600
5.1 800 480
5.2 600 360
5.3 400 240
5.4 200 120

FERTILIZATION

Amount of Fertilizer.- About 2,500 pounds per acre of 6-8-8 fertilizer applied
in bands is currently recommended for growing potatoes in the Hastings section.
Proportionately less of higher analysis materials can be used. For example, 2,200
pounds of 7-9-9 contains approximately the same amount of plant nutrients as 2,500
pounds of 6-8-8 and is usually cheaper per unit of plant nutrient.

Contents of Fertilizer.- The fertilizer should contain about 2 percent solu-
ble magnejsia. For average conditions, one fifth of the nitrogen should be nitrate
nitrogen. For new lands or where leaf roll has been prevalent, the nitrate nitro-
gen can be increased up to one third of the total nitrogen present. Generally, the
use of more than one unit of nitrogen from insoluble sources cannot be justified
for potato fertilizers. The chlorine content should be not more than three per-
cent, the lower the better if a dry season is encountered, or if harvest is to be
delayed beyond the average digging dates. Tests in 1955 and 1957 showed that
Sebago potato yields were increased about 15 percent by using fertilizer which
derived its potassium from sulfate of potash rather than muriate (chloride) of
potash.

Side Dressing.- New lands or ones previously showing leaf roll should be side-
dressed with about 150 pounds of nitrate of soda-potash, or its equivalent per acre
at about 40 days after planting. This sidedressing, ammonium nitrate, or a complete
fertilizer are recommended after heavy leaching rains have occurred.


References

l* Volk, G. M. and Nathan Gommon, Jr. Effect of liming and fertilization on
yield and correlation of nutritional leaf-roll of Irish potatoes.
Fla. Agr. Exp. Sta. Bul. 504. 1952.
2. Myhre, D. L., E. N. McCubbin and G. M. Volk. Effects of irrigation, ferti-
lization and seeding rates on potato yields in 1955 at Hastings, Florida.
Fla. State Hort. Soc. Proc. 68: 233-235. 1955.




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