What is the Be What is the Be est Form of est Form of Nitrogen fo - - PowerPoint PPT Presentation

What is the Be What is the Be Nitrogen fo g Orchar

Bruce W

est Form of est Form of

• r Pecan

rds?

• W. Wood

#1--From a Tree Not all Forms of Nit Not all Forms of Nit

N atoms have differ

 N3-

3- (i.e., surplus

(i.e., surplus

 Ammoni

Ammonium um

N-atoms have differ

 N2+

2+ (i.e., def

(i.e., deficien cient



Hydrazine (r Hydrazine (roc

 N3+

3+ (i.e., def

(i.e., deficien cient

Increasing availability

• f chemical energy

(gain or acceptance of

 Amin

Amine (urea, e (urea, p amm ammoni nia a

 N4+

4+ (i.e., def

(i.e., deficien cient

(gain or acceptance of electrons; reduction; gain of energy)



Nitrit Nitrite

 N5+

5+ (i.e., def

(i.e., deficien cient

 Nitrat

Nitrate

Different N forms possess different chemic

e’s Perspective: trogen (N) are Equal trogen (N) are Equal

ent oxidation states

• f 3
• f 3 electr

electrons):

• ns):

ent oxidation states

t 2 2 electr electrons):

• ns):

cke ket f fuel) t 3 3 electr electrons):

• ns):

Decreasing availability

• f chemical energy

(loss or donation of

peptides, pr eptides, proteins); eins); t 4 4 electr electrons):

• ns):

(loss or donation of electrons; oxidation; release of energy)

t 5 5 electr electrons):

• ns):

cal energy potentials for plant metabolism.

From a Tree’s Not all Forms of Nit Not all Forms of Nit

Under normal conditions, mos converted to ammonium but

 N3-

3- (i.e., surplus

(i.e., surplus

 Ammoni

Ammonium um

converted to ammonium, but

 N2+

2+ (i.e., def

(i.e., deficien cient



Hydrazine (r Hydrazine (roc

 N3+

3+ (i.e., def

(i.e., deficien cient

Increasing availability

• f chemical energy

(gain or acceptance of

 Amin

Amine (urea e (urea, , p amm ammoni nia a

 N4+

4+ (i.e., def

(i.e., deficien cient

(gain or acceptance of electrons; reduction; gain of energy)



Nitrit Nitrite

 N5+

5+ (i.e., def

(i.e., deficien cient

 Nitrat

Nitrate

*Different N forms possess different chemic

s Perspective: rogen (N) are Equal* rogen (N) are Equal

st nitrate within the plant is eventually is energetically expensive

• f 3
• f 3 electr

electrons):

• ns):

is energetically expensive.

t 2 2 electr electrons):

• ns):

cke ket f fuel) t 3 3 electr electrons):

• ns):

Decreasing availability

• f chemical energy

(loss or donation of

peptides, pr eptides, proteins); eins); t 4 4 electr electrons):

• ns):

(loss or donation of electrons; oxidation; release of energy)

t 5 5 electr electrons):

• ns):

cal energy potentials for plant metabolism.

#2—Pecan Is an Amm

• Consider Pecan Ecosystem
• Consider Pecan Ecosystem

A i l i A i Ammonium loving vs. Ammonium

• nium Loving Species

ms and Their Ecophysiology- ms and Their Ecophysiology-

i t l t I t di t i m intolerant vs. Intermediate species

Alluvial Lands:

• A Co-dominate “Climax” species in certain

and a “Subclimax” in other forest types.

►P p

• “

Pecan

forest types,

Water Table Water Table

Pecan is also native to deep well drained pockets on “upland soils”; and near small rivers/creeks

• n ridges of well drained “first bottom” or where the
• n ridges of well drained first bottom , or where the

second bottom” nearly intersects the watercourse.

T il i i h i Top soil zone is rich i

Nitrate-N dominate Nitrate N dominate (ammonia intolerant sp

N(5+)O3 i d i i tt in decaying organic matter

es Organic-N and Ammonium-N are common (ammonia-loving species)

N(3-)H4

es pecies)

4

Pecan is exposed to considerable (organic and ammonium) in its natu

So, pecan exhibits evidence of being an “amm (typically shade tolerant mid- late-succession (typically shade tolerant mid late succession

N(5+)O

Nitrate loving continuous shoot growth sp (Pioneer species)

N(5+)O3 W

reduced-N ural habitats

monium loving” (reduced-N) species!!! al species) al species) ecies

N(3-)H4

Water Table

Characteristic Nitrat sp

Pioneer species in forest succession Heavy reliance on subsurface w ater table Diffuse or semi diffuse porous cambial grow th Diffuse- or semi-diffuse porous cambial grow th Ring- or semi-ring porous cambial grow th Indeterminate shoot grow th pattern Determinate shoot grow th pattern Early budbreak in spring Delayed budbreak in spring Produces small seeds Produces medium to large seeds Shade tolerant Shade tolerant Shade intolerant Relatively small N storage pool in dormancy Relatively large N storage pool in dormancy Highly tolerant to anaerobic soils Alternate bearing and nut masting

te-N loving pecies z Ammonium-N loving species y Pecan

Yes No No Yes No No Yes No No Yes No No No Yes Yes Yes No No No Yes Yes Yes No No No Yes Yes Yes No No No Yes Yes No Yes Yes No Yes Yes Yes No No Yes No No No Yes Yes Yes No No No Yes Yes

#3—Trees Can Respond D Solution Nitrate:A Solution Nitrate:A

 Vegetative growth is favored by nitrat

T it t t i h t

 Tree nitrate can act as a quasi-hormone t

result in enhanced vegetative growth

 Nitrate-N triggers “switching” of tree resour

 Less fruiting  More likely to trigger deficiencies of esse

 Nitrate-N is best if trying to get trees to grow  Urea-N is converted to ammonium and then

being absorbed as urea by roots; however, f th l t f d high g f the plant as a preferred high energy form o

 Reproductive growth is favored by am

 Tree ammonium-N enhances synthesis of  Tree ammonium N enhances synthesis of

proteins (and enzymes), and nucleic acids

 Ammonium-N triggers “switching” of tree re

 More fruiting and reduced incidence and  Because ammonium competes with K in  Because ammonium competes with K in

*Root uptake of nitrate and ammonium‐N is regulated

Differently to Different Soil Ammonium Ratios Ammonium Ratios

te-N* usage [N:A = 5-10:1 (?)]:

t t igg d t h l h g th t to trigger downstream hormonal changes that

rce partitioning to favor vegetative growth structures ential and beneficial nutrient elements w fast; potential issues with low P n nitrate very rapidly in most soils, with little or none foliar applied urea-N is rapidly absorbed and used by f N f N

mmonium-N* usage [N:A = 2-3:1 (?)]:

f carbohydrates amino acids peptides f carbohydrates, amino acids, peptides, s, giving enhanced reproduction.

esource partitioning to favor reproduction d severity of nutrient element deficiencies n uptake be careful to ensure good K nutrition n uptake, be careful to ensure good K nutrition

by tree demand and sugar supply in roots

Synthetic Nitrogen Sources



Ammonium:

 ~100-1000:1 preference by roots over nitrat  A high energy N form (highly reduced N atom  Not as easily lost as nitrate due to leaching  Uptake is best at pH 7, declines as soil pH d  Trees tend to have higher carbohydrate and  Easier to get phytotoxicity using ammonium

have to be careful to not over fertilize (very

 Acidifies soils as it is converted to nitrate in

l t (r l 3H+ i i t il l ti elements (releases 3H+ ions into soil solutio buffered high CEC soils)

 Rapidly converts to nitrate form in soils unle

conversion is more rapid in high pH soils.

 Subject to loss when soils are waterlogged a  Subject to loss when soils are waterlogged a  Can suppress K uptake, so can trigger K def

also suppress Ca, Mg, and transition metals

 Increases uptake of S, P, Cl, and Si

N(3 N(3-

s: Ammonical (Ammonium)

te ms)

• r denitrification, as ammonia binds to soil particles

rops protein levels than when fertilized with nitrate-N m, due to rapid and great uptake preference by roots, so toxic to plant cells) the soil, and therefore affects availability of other l CEC il r r tibl th high r

• n; low CEC soils are more susceptible than higher

ess “Nitrification Inhibitors” are use to retard oxidation; and also due to denitrification and mineralization and also due to denitrification and mineralization ficiency if tree is low in K (e.g., June-drop of fruit). Can s (Fe, Mn, Cu, Zn, Ni, Mo).

)H

• )H4

Synthetic Nitrogen

 Nitrate:

 Dominate form of N in soil solution  Most of N absorbed by roots is nitrate  A low energy N form (highly oxidized N atoms  More easily lost than ammonium due to leac  Trees will hyperaccumulate (luxury consumpt

used

 Trees are far more tolerant to high nitrate tha  Trees are far more tolerant to high nitrate tha  All N-forms will convert to nitrate in soil withi

matter

 Can suppress P uptake, so can trigger P defic

same is true for S Cl and Si same is true for S, Cl, and Si

 Enhances uptake of Ca, Mg, and transition m

N(5+) N(

)

n Sources: Nitrate

s) ching , as not as much is bound to soil particles tion) nitrate, but it is not necessarily assimilated and an to high ammonium, so low chance of phytotoxicity an to high ammonium, so low chance of phytotoxicity n 2-3 week unless they are bound up to soil or organic ciency if tree is low in P and add a lot of nitrate. The metals

)O3

• )O3

Commercial Orchards Are

►Relatively little “reduced-N” ► Lots of nitrate-N (“oxidized-N”) ► Lots of water via irrigation ► Lots of water via irrigation

e Artificial Pecan Habitats

► Lots of vegetative growth ► Nutrient deficiencies ► Less reproductive growth

#4--N Usage Efficiency and Assimilat Other Elements, Especially Sulfur (S) a

 The N and S assimilation (integration int

The N and S assimilation (integration int biochemicals) processes within pecan tr deficiency of one “repressing” assimilat biochemicals) of the other.

 Can ha

Can have high leaf tissue high leaf tissue N; y N; yet ha have a ph a physio ysio

 Can ha

Can have high leaf tissue high leaf tissue N; y N; yet, ha have a ph a physio ysio insuf insuffic icient sulfur nt sulfur (als (also applies

• applies t

to Mn, Mn, Cu, Cu, Zn, Zn,

 Mo, F

Mo, Fe, and , and S are k S are key y com components of

• nents of nitrat

nitrate r e re key com y components of nitrit

• nents of nitrite

e reductase reductase (t (to mak

• make

 Cyst

Cysteine eine and and Methionine Methionine S S containing amino containing amino

 Cyst

Cysteine eine and and Methionine Methionine, S S containing amino containing amino enzymes. enzymes.

 Ni

Ni is k is key com y component of

• nent of urease and pr

urease and probably

• bably ot

 N @

N @ ~2.3-2.8%? dw; S ~2.3-2.8%? dw; S @ @ 0.20-0.50% dw 0.20-0.50% dw

 Failure to consider tree S status (same i

applying N can be a costly mistake.

 Spring foliar sprays of a balanced micro

p g p y important for best usage of N applied

tion by Trees Depend on Status of and Micronutrients (Fe, Cu, Mo, Ni…)

to needed N or S containing to needed N or S containing rees are tightly linked, with a ion (conversion into needed

• logic
• logical def

al defici ciency of ency of N N because of because of

• logic
• logical def

al defici ciency of ency of N N because of because of F Fe, Ni, , Ni, and Mo) and Mo) eductas ductase e enzyme; and Cu, F enzyme; and Cu, Fe and S are and S are ammonium in the plant) ammonium in the plant) acid acids are k are key y com components of

• nents of almost all

almost all acid acids, are k are key y com components of

• nents of almost all

almost all ther N-associat her N-associated ed enzymes enzymes

is true for micronutrients) when nutrient mix is potentially very p y y

Common Synthetic

Fo Form Chemical %N Sulfur Solid Solid Urea rea 46 No S l S lid C l C l i A A i 32 32 N Solid lid Calcium um A Ammon mmonium um Nitrat Nitrate 32 32 No Solid Solid Ammoni mmonium Sulf m Sulfat ate 21 Yes es Liq Liquid id UAN-32 N-32 32 32 No No Liq Liquid id UAN-28+S N-28+S 28 28 Yes Liq Liquid id 24-0-0-3.5S

• 0-0-3.5S

24 Yes es Liqu quid UA UAN-19 19 19 19 No Liq Liquid id 15-0-0-3S

• 0-0-3S

15 Yes es

* Best source of N is deco

Nitrogen Sources*

Ammoni Ammonium % um % Amin mine (U (Urea) rea) Nitrat Nitrate % e % $/U /Unit nit N N (U (Urea) rea) % 100% 00% 0.49 .49 25 25 75 75 0 6 0 60 25 25 75 75 0.60 60 10 100 0.61 25 25 50 50 25 25 0.55 0.55 31 46 46 23 23 0.56 0.56 33 33 22 22 45 45 0.55 0.55 33 33 57 0.39 .39 ? ? ? ? ? 0.47

• mposing organic matter

Limiting F

1800

)

1400 1600

s/acre)

800 1000 1200

eld (lbs

400 600 800

shell yie

200 40 80 120

In-s

40 80 120

Applied nitrogen (l

Factor(s)?

A limiting stres factor (inshell lbs/acre) No stress factors (inshell lbs/acre) Limiting factors: 160 200 240 Limiting factors: Low NH4+, S, Mo, Cu, Ni, Zn, Fe, B, Mg, etc.; water, sunlight; nitrate vs ammonium, 160 200 240

bs N/acre)

Other Cons

 Most pecan orchards are proba

especially nitrate-N I t g t b i

 In most cases, we can get by wi

ammonium-N is properly applie

 Excessively shady trees do not r  Excessively shady trees do not r

exposed trees, but hyperaccum

 Use ammonium-N or urea-N on

Use ammonium N or urea N on trees, not nitrate-N.

siderations

bly over fertilized with N, th l i g l N/ if th applying less N/acre if d require as much N as well sun require as much N as well sun- ulate nitrate-N mechanical hedge-pruned mechanical hedge pruned

Than



Image by Dr. Ted Cottrell, USDA-ARS g y ,

nks!!!