Pecan Leaf Elemental Sufficiency Ranges and Fertilizer

Report
Michael Smith – Oklahoma State University
Charles Rohla – Samuel Roberts Noble Foundation
Bill Goff – Auburn University
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Revised Nutrient Sufficiency Ranges and
Fertilizer Guidelines for Pecan
• Maintaining a balance
among nutrients is
essential.
• Excessive application of a
nutrient will not increase
growth or production, but
will increases cost and
may cause other
problems.
• Shortages reduce growth,
yield, cold hardiness and
the ability to cope with
stress.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Is a managed nutrition program important?
• Represents nutrients available and absorbed by
the tree.
• Leaf elemental concentrations are closely
correlated with tree performance.
Why not soil samples?
• Frequently little, if any, correlation between soil
test levels of nutrients with tree performance or
leaf elemental concentrations.
• Primary value of soil sample is pH and to
diagnose problem areas.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Why leaf samples?
• Leaves from the 1st
growth flush that are fully
expanded, but before nut
nutrient demand
increases.
• Typically July.
• Collect – the middle
leaflet pair from the
middle leaf on sunexposed shoots.
• Sample ≈100 leaflet pairs
representative of the
orchard.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
When and what to sample?
• Physiological nutrient
requirement for pecan is
not affected by
geographic location.
• Little effect of yield on
nutrient requirement.
Nutrient
Nutrient
removal/100 lbs
Nitrogen
1.3 lbs
Phosphorus
0.4 lbs
Potassium
0.6 lbs
Calcium
0.2 lbs
Magnesium
0.2 lbs
Iron
0.00001 lbs
Zinc
0.00002 lbs
Manganese
0.00002 lbs
Copper
0.000001 lbs
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Are elemental sufficiency ranges
among locations similar?
• Native and low-input orchards are:
– Less productive
– Lower nut value
– Fewer inputs such as irrigation, crop load rarely
managed, less pest control, greater damage
tolerance.
– Marketed to shellers vs. “gift-pack” and
international markets.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Native & low-input orchards
vs. high-input orchards
• <2.3% Low. Double last year’s N application rate. If
the orchard did not receive N last year apply 150
lb/acre N.
• 2.3% to 2.5% Normal. Optimum. Continue present N
application rate.
• 2.5% to 2.7% Normal. Nitrogen application can be
reduced without affecting yield or nut quality.
Decrease the application rate by 20%.
• 2.7% to 3.0% Normal. Nitrogen application can be
reduced without affecting yield or nut quality.
Decrease the application rate by 50%.
• >3.0% Above normal. Withhold all N for 1 year.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Nitrogen – Native & low-input
• <2.3% Very low. Double present N application rate.
• 2.3% to 2.4% Low. Increase the present N rate by
30%.
• 2.4% to 2.7% Normal. Optimum. Continue the
present N application rate.
• 2.7% to 3.0% Normal. Nitrogen application can be
reduced without affecting yield or nut quality.
• >3.0% Above normal. Decrease application rate by
50%.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Nitrogen – High-input orchard
• Greatest demand
– ≈ 3 weeks after budbreak, late water stage.
• Urea - problem with N volatilization
– Temperature > 70oF, moist soil, high pH
– Requires at least ¼” of rain or irrigation to incorporate
• Sandy soils or flooding potential
– Split application beneficial
– Pre-budbreak & late-May
– Pre-budbreak to mid-May & late water stage
• Ground cover
– Legume may supply all the N needed
– Non-legume: applying pre-budbreak appears to favor tree
– Application in the weed free area surrounding the tree
• Injection of liquid N into drip or micro-sprinkler system
– Minimizes N loss, flexible, economical to use multiple N applications
– Up to 50% N reduction without loss of tree performance
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Nitrogen application factors
Native & low-input orchard
• < 0.12% Low
• ≥ 0.12% Normal
High-input orchard
• < 0.14% Low
• ≥ 0.14% Normal
Apply as a banded application (100 to 150 lb/a P2O5) within the wetted zone if
irrigated. Otherwise, about mid way between trunk and canopy periphery. Prebudbreak & late water stage have both been effective. May have faster response
from late water stage application.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Phosphorus
Goff, 2012
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Native & low-input orchards
• < 0.85% Low.
• ≥ 0.85% Normal.
High-input orchard
• < 1.0% Low.
• ≥ 1.0% Normal.
Apply as a banded application (100 to 150 lb/a
K2O)within the wetted zone if irrigated.
Otherwise, about mid way between trunk and
canopy periphery. If both phosphorus and
potassium are needed they can be blended and
applied together.
P & K symptoms look
alike. P symptoms may
develop relatively early in
the growing season, as
above. P symptoms more
likely as nuts fill.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Potassium
• Sulfur
• < 0.20% Correct with using (NH4)2SO4 for N and
ZnSO4 foliar application for Zn.
• Calcium
• < 0.70% Apply lime based on soil test with target of
6.8 pH.
• Magnesium
• < 0.30% Soil test and if pH low adjust with dolomitic
lime. Otherwise use MgSO4 at manufacturer’s
recommended rate.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Other macro-nutrients
• < 15 ppm Apply 3 foliar applications of Solubor
(20.5% B) at 0.5-1.0 lb/acre of material. Begin as
the 1st leaf unfurls during budbreak, and then
twice more at 2-week intervals.
• 15 ppm to 300 ppm Normal, none needed.
• > 300 ppm Excess. Determine source, usually
irrigation water, and correct.
In Georgia, foliar B application applied beginning during
pre-pollination increased fruit retention and kernel % of
‘Desirable’.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Boron
• < 100 ppm Apply 3 foliar applications of
MnSO4 (32% Mn) at 6 lbs/acre of material.
Begin as the 1st leaf unfurls and then twice
more at two week intervals or with the 1st and
2nd generation pecan nut casebearer sprays.
MnSO4 and ZnSO4 can be tank mixed and are
compatible with most pesticides.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Manganese
• < 60 ppm
– Bearing trees ― 3 application of ZnSO4 at 3 to 6
lbs/acre of material at as 1st leaf unfurls, 1st generation
PNC and 2nd generation PNC. If severe or high-input
add an application between budbreak and 1st
generation PNC. 40 ppm is adequate if foliar Zn not
applied, especially for native and low-input orchards.
– Non-bearing ― ZnSO4 at 1 to 2 lbs/100 gal of material
as 1st leaf unfurls and then at 2-week intervals as long
as new growth is present.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Zinc
• < 50 ppm Cool, wet
springs can induce an Fe
deficiency that is
corrected when
conditions improve.
– If deficiency acute or
persists 2 years use a foliar
applied Fe Chelate or a
soil applied EDDHA Fe
Chelate.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Iron
Heerema et al.
Copper
• < 6 ppm Copper is rarely
deficient. Use either CuSO4
or Cu Chelate.
Nickel
• < 2.5 ppm apply Nickel Plus
or Nickel CBM foliarly
• Frequently associated with
old orchard sites with sandy
soils, particularly those soils
with marine origin.
Oklahoma State University
Auburn University
Samuel Roberts Noble Foundation
Copper and Nickel

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