Transcript Basics of Plant Nutrition

Micronutrient Needs for Crops
on the Southern Plains
Dave Mengel
Professor of Soil Fertility
Kansas State University
The Essential Elements
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Carbon, Oxygen, Hydrogen
Macronutrients
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Secondary Nutrients
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Ca, Mg, S
Micronutrient metals
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N, P, K
Fe, Zn, Mn, Cu, Ni
Other micronutrients
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Cl, B, Mo
Micronutrient Metals
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Of the five micronutrient metals:
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Zinc deficiency is common on corn and
grain sorghum
Iron deficiency is common on corn, grain
sorghum and soybeans
Manganese deficiency is not common in
the region, but is of interest due to reports
of Manganese x glyphosate interactions in
RR soybeans
Micronutrient Metals
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Of the five micronutrient metals:
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Copper is not a problem in the region, but
recently “foreign experts” have been
raising questions concerning potential Cu
deficiencies in wheat.
Nickel is of academic interest only at this
time.
Zinc
Zinc
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Zinc: the most common micronutrient
deficiency of corn in the region
Deficiencies also are seen in sorghum,
soybeans and pecans.
Deficiencies in wheat and sunflowers are rare.
A cofactor in many enzyme processes in
plants, the exact role of the zinc in these
reactions is generally not known.
Zinc is generally immobile in the plant, and
deficiency is commonly noted on the young
tissue.
Zinc
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Multiple symptoms have been described for
zinc deficiency, with some genotypes
responding differently.
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In corn a stunting, yellowing at the whorl and
intervienal striping is common.
A stunting or rosetting and internode shortening
of young seedlings with distinct white band on one
side of the mid-rib is also common.
Zinc Deficient Corn
Where Zinc Deficiency is Seen
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Zinc is low in many soils across the
region, and especially in areas of high
pH, and where organic matter has been
removed, such as eroded areas or land
leveled fields.
Assessing Zinc Deficiency
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The DTPA Soil Test is commonly used
for zinc
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The critical level ranges from 0.5 to 1 ppm
Zn for most crops
Levels 0-0.5 considered strongly deficient
Applications are roughly 1 lb Zn per 0.1
ppm below the critical level
Correcting Zinc Deficiency
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Application of zinc can be by:
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Broadcast applications of a high
percentage water soluble zinc source, such
as zinc sulfate, oxysulfate or zinc chelate.
Band application of these same products
with starter fertilizers.
Foliar application of zinc, especially on
pecans and rice.
Application of animal manure. Most
manure contains large amounts of zinc
Iron Chlorosis
Iron in Plants
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Iron deficiency in field crops is common, especially
on corn, soybeans, and sorghum. It is less common
on wheat, but does occur.
Iron is the most common micronutrient deficiency of
turgrass and ornamentals in Kansas. Iron chlorosis
occurs frequently on lawns in new developments or
on golf greens built with unwashed river sand.
Considerable difference exists between varieties in all
crops. Corn and soybean varieties are screened for
iron chlorosis.
Iron is a structural component of cytochromes,
hemes and other substances involved in oxidationreduction reactions in photosynthesis and respiration.
Iron Deficiency Symptoms
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Iron is very immobile in plants, once
deposited in tissue, iron is not easily
remobilized to younger tissue.
Deficiency symptoms are generally found in
the youngest leaves on the plant.
Young leaves develop an intervienal chlorosis
that rapidly progresses over the entire leaf.
This may include a bleaching of the veins and
in severe cases the entire leaves will turn
white.
Iron Chlorosis in Sorghum
Iron Chlorosis
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Corn
Iron Chlorosis
Iron Chlorosis in Wheat
Where Does Fe Chlorosis Occur?
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On high pH depressional soils
Most commonly found in “spots” in the
field
In eroded spots or leveled areas .
Assessing Iron Deficiency
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The DTPA test is sometimes used, but it
is not reliable
pH and OM may be better indicators
Correcting Iron Deficiency
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Foliar applications of 2% ferrous sulfate
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May take multiple applications
Band applications of 6-10 pounds
soluble iron
Animal manure
Lowering pH works in home hort or turf,
but too expensive for field applications
Manganese deficiency
Manganese in the Plant
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Manganese is involved in photosynthesis,
particularly in the evolution of O2.
It also is involved in a number of oxidationreduction reactions and in decarboxiliation
and hydrolysis reactions.
In many plant reactions Mn and Mg can
partially substitute for each other.
May be a relationship with the RR gene in
soybeans causing Mn deficiency
Manganese Deficiency Symptoms
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Like iron, Mn is very immobile in the plant
and deficiency symptoms occur as intevienal
chlorosis on young leaves.
Manganese deficient leaves tend to maintain
a greenish tint, unlike iron chlorosis where
they turn yellow or bronze.
Manganese deficiency is not common in the
region, but occurs on high pH, high organic
matter soils, found in the eastern cornbelt.
Mn and RR Soybeans
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Speculation that the RR gene has added a
sensitivity to Mn deficiency. Reports and
research in Indiana and Kansas.
The yellow flashing which occurs after
glyphosate application in some fields has
been called Mn deficiency.
Research with RR isolines suggest this could
be the case, but likley on marginal Mn sites.
Manganese Deficiency
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Corn
Manganese Deficiency
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Soybeans
Manganese Deficiency
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Wheat
Assessing Mn Deficiency
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Mn Soil Tests Don’t Work
pH and OM may be useful in deficient
regions (eastern US)
Correcting Mn Deficiency
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Like iron, the soil contains large
amounts on Mn, its an availability issue.
Foliar application
Band application
Band apply an acid forming fertilizer (N)
Copper Deficiency
Where is Copper Deficiency
Found?
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Deficiency is not found in the Southern Plains.
It looks similar to drought or heat damage on
wheat and has been some confusion recently
It is common on organic soils in Canada and
the Great Lakes region, and on organic soils
or deep acid sands in the southeastern US,
which have never received applications of
copper as a fertilizer or as a fungicide.
On extremely weathered oxisols or sands in
tropical regions and Australia.
Copper in Plants
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Copper is involved in many complex
enzyme systems where redox potential
is critical. Examples include the
enzymes involved in lignin and melanin
production.
Copper Deficiency Symptoms
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Corn and wheat are the two commonly grown
field crops most likely to be deficient in
copper.
Like most metals, copper is not very mobile
in the plant, with deficiency symptoms
occurring on the younger tissue.
Copper deficiency results in a unique necrosis
and twisting of the leaf tips of young
seedlings. Copper is bound very strongly by
soil organic matter..
Corn
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Wheat
Correcting Copper Deficiency
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Broadcast applications of 5 pounds Cu,
20 pounds Copper sulfate per acre.
Good residual effects.
Foliar applications of 1-2 pounds Copper
sulfate per acre.
Nickel
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Recently confirmed as an essential
element.
Only one field deficiency ever found.
Primarily of academic interest.
Micronutrient: Non-metals
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Of the three non-metals:
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Boron deficiency occurs rarely on alfalfa in
SE KS and Oklahoma and on peanuts in OK
Old research found Mo deficiencies on
soybeans in SE KS
Recent reports suggest Mo deficiency may
occur on soybeans in Central Kansas also.
Chloride response occurs frequently on
wheat, sorghum and corn in NE and
Central KS where no potash has been
applied.
Boron
Boron Deficiency
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Since B is involved in cell division,
deficiency symptoms are cessation of
growth at the terminal bud, followed by
yellowing and death of young leaves.
Severely impaired fruit and seed set are
late season symptoms on many crops.
Boron deficiency is commonly confused
with potato leaf hopper damage in
alfalfa
Where Boron Deficiency is Seen
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In Kansas, boron deficiency is
occasionally seen on alfalfa, primarily in
SE Kansas.
There have been reports of boron
response in corn and sunflower in
Nebraska, cotton in Missouri, and
peanut in Oklahoma.
Boron Deficient Alfalfa
Boron Deficiency in Corn
Boron Toxicity
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Corn
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Soybeans
Assessing Boron Deficiency
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A hot water soluble soil test is sometimes
used for boron. However it is not well
correlated with plant growth, so is not
recommended.
Plant analysis is the preferred diagnostic
method.
Since B deficiency is easily confused with
leafhopper damage, and B toxicity can be a
problem, care should be used when applying
boron
Correcting Boron Deficiency
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Boron is highly toxic to germinating
seeds of corn and soybeans. Boron
fertilizers should never be applied as a
"starter fertilizer" in or near the row at
planting time..
Application of boron can be by:
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Broadcast applications of 1-2 pounds of B
as granular borate.
Foliar application of 0.1-0.5 pounds soluble
borate.
Chloride
Background
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Chlorine has been generally accepted as an
essential element since 1954.
Responses to chloride fertilization have been
reported since the 1800’s.
Chloride plays many roles in plant nutrition,
but role in disease suppression, especially leaf
rust in wheat and stalk rot in sorghum and
corn, sparked interest in chloride in Kansas.
Yield responses to potash on high K soils also
sparked interest in other states in the plains.
Chloride Fertilization of Wheat in
Kansas
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Some of the first chloride work reported in
Kansas was done in the early to mid 1980’s
by Larry Bonczkowski comparing KCl to
fungicides on leaf rust suppression.
Mark Hooker at Garden City, and Ray Lamond
in Manhattan followed that up with work on
yield response to chloride on wheat in the
mid-80’s.
Ray Lamond also screened wheat varieties for
differences in response/sensitivity to chloride.
RESPONSE OF WHEAT TO CHLORIDE
FERTILIZATION IN KANSAS, 1990-2006.
_______________________________________________
Chloride applied Grain Yield
Percent Chloride
lbs Cl-/acre
bu/A
in leaf at boot
_______________________________________________
0
48.4 b
0.29 c
10
51.7 a
0.38 b
20
52.5 a
0.43 a
LSD 0.05
1.3
0.03
n
34
30
_______________________________________________
Affect of Applied Chloride on Leaf Chloride at
Responsive Sites
Leaf Chloride, percent
0.7
0.6
0.5
0.4
0.3
0.2
2
y = -0.0004x + 0.0148x + 0.2443
R2 = 0.1909
0.1
0
0
5
10
15
Applied Chloride, lbs/a
20
25
Sorghum: 1996 to date
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Unlike wheat, no visual chloride deficiency
symptoms have been described on sorghum.
There appears to be a relationship in
sorghum between chloride nutrition and stalk
quality.
The first chloride studies on sorghum were
conducted by Lamond in 1996.
23 chloride response trials on dryland
sorghum have been reported, by several
people, primarily in central Kansas.
Response of dryland grain sorghum to applied
chloride fertilizer in Kansas, 1996-2006.
________________________________________________________
Chloride applied
Grain Yield
Percent Chloride in leaf
lb Cl-/acre
Bu/A
at boot, percent
________________________________________________________
0
98.5 b
0.10 c
20
108.2 a
0.24 b
40
109.9 a
0.33 c
LSD 0.05
2.4
0.05
n
20
11
________________________________________________________
Corn: 1996 to 2001
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Like sorghum, no visual chloride deficiency
symptoms have been described on corn.
There appears to be a relationship in corn
between chloride nutrition and stalk quality.
The first chloride studies on corn were
conducted by Lamond in 1996.
Only 11 chloride response trials on dryland
corn have been reported, all in central
Kansas.
Response of dryland corn to applied chloride
fertilizer in Kansas, 1990-2001.
____________________________________________________________
Chloride applied
Grain Yield
Percent Chloride
lb Cl-/acre
Bu/A
in earleaf at tassel
____________________________________________________________
0
104.4 b
0.17 c
20
108.9 a
0.27 b
40
111.6 a
0.36 c
LSD 0.05
3.4
0.05
n
11
11
____________________________________________________________
Soil test chloride interpretations and fertilizer
recommendations for Kansas.
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Soil Chloride in a 0-24" sample
Cl Recommended*
Category
lb/acre
ppm
lb/acre
____________________________________________________________
Low
<30
<4
20
Medium
30-45
4-6
10
High
> 45
>6
0
____________________________________________________________
*Recommendations for corn, sorghum and wheat only.
Molybdenum
Molybdenum in Plants
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Molybdenum is involved in the nitrate
reductase and nitrogenase systems in
plants.
Plants require very low levels of Mo. In
legumes, enough molybdenum can be
present in the seed to meet the needs
of the plant. But subsequent
generations may need additional
molybdenum.
Molybdenum Deficiency
Symptoms
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Molybdenum deficient plants appear
stunted, light green and N deficient.
Molybdenum
Where Does Molybdenum
Deficiency Occur?
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On low pH, weathered soils in SE and
SC Kansas. Molybdenum deficiency is
not common in Kansas, but occurs most
frequently on old, highly weathered acid
soils.
Recent reports suggest low
molybdenum in seed may be
contributing to Mo deficiencies under
high pH.
Assessing Molybdenum
Deficiency
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No reliable soil test is currently
available.
Soil pH and seed molybdenum may be
better indicators of molybdenum needs.
Plant analysis is a good diagnostic tool.
Correcting Molybdenum
Deficiency
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Liming
Seed treatment with 1-2 ounces of
ammonium molybdate.
Foliar applications of ammonium
molybdate of 2-4ounces per acre.
Due to the toxic nature of molybdenum
to ruminant animals, molybdenum
fertilization is normally not
recommended.
Questions?