Bruce&Linquist UCDavis,Dept.PlantSciences

Bruce Linquist UC Davis, Dept. Plant Sciences

University of California Coopera;ve Extension July 24, 2015

Fertility and Crop Nutrition

UC DAVIS University of California

Outline • Why is nutrient management important? •  Rice soils •  Approaches to nutrient management •  N, P, and K

–  Func=on and deficiency –  Nutrient in the soil –  4R management –  Effect of straw management

•  Adjus=ng nutrient management for different systems –  Drill-‐seeding –  Stale seedbed


Why is nutrient management important?

•  Economics –  Cost –  Yields

•  Pollu=on –  Ground and surface waters –  Air quality

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1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015

Dollars per to

n of fe

r;lizer

Fer;lizer prices 1960-‐2013 (USDA)

Nitrogen solu=ons (30%)

Urea 44-‐46% nitrogen

Super-‐phosphate 44-‐46% phosphate

Potassium chloride 60% potassium


Flooded rice soils in California •  Aerobic and anaerobic soils

–  The amount of oxygen in soils affects: •  Soil microbiology •  Soil pH •  Nutrient transforma=ons

•  Heavy clay soils that are rela=vely impermeable –  High reten=on of nutrients –  Limited leaching –  A lot of potassium


Approaches to nutrient management

•  The goal – match nutrient supply with crop requirements – minimize nutrient losses from fields.

•  Properly managed fer=lizers – support cropping systems that provide economic, social and environmental benefits.

•  Poorly managed nutrient applica=ons can – decrease profitability and increase nutrient losses, poten=ally degrading water and air quality.


Amount of nutrient in plant at harvest (lb/1000 lb grain yield)

15.6

2.7

15.1

1.6

3.6 3.1

0.45 0.45 0.04 0.01 0.01

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

N P K S Ca Mg Fe Mn Zn Cu B

Nutrie

nt in plant at ;

me of harvest

Nutrient

Nutrient uptake and root growth

Plan;ng

What is this material? 0.7 0.3 1.7

Nutrients (lb) in 1 ton (2000 lb) of rice straw

•  N 14 lb •  P 6 lb •  K 28 lb

•  Value (2012 fer;lizer prices)

•  $31.34


Straw management and how it affects nutrient management

•  Removing straw will increases nutrient requirement of all major nutrients-‐especially K

•  Important to incorporate/roll straw to facilitate decomposi=on during winter

•  Can reduce N inputs by 25 lb/ac. IF straw is incorporated

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-25 SP +25

BurnedIncorporated

lb a

cre

-1 a

t 14%

moi

stur

e


Maximizing nutrient use efficiency through 4R management

•  The 4 Rs – Right rate – Right source – Right place – Right =me


Nitrogen

•  Applied in highest amount •  Most costly nutrient •  Crop suscep=ble to misuse

–  too liile: low yields –  too much: lodging, delay harvest, pests, increased cost, off-‐site pollu=on

•  Suscep=ble to the most losses •  Overuse can lead to environmental concerns

– water quality –  air quality


Nitrogen transforma=ons in flooded soils

Buresh et al., 2008

N i t r o g e n Fixa;on

The process by which atmospheric nitrogen is converted to biologically usable forms of nitrogen by microorganisms.

Mineraliza;on The breakdown of organic maier resul=ng in the release of ammonium (NH4) and other nutrients which can be used by plants.

Nitrifica;on The conversion of ammonium (NH4) to nitrate (NO3).

Denitrifica;on The conversion of nitrate (NO3) to nitrogen gas (N2), resul=ng in a loss of plant available N.

Immobiliza;on The assimila=on (tying up) of inorganic N (NH4 and NO3) by microorganisms resul=ng in the nitrogen being unavailable for plant uptake.

A m m o n i a vola;liza;on

The loss of ammonia gas to the atmosphere, following the conversion of ammonium (NH4) to ammonia (NH3).


Nitrogen transforma=ons in flooded soils

Buresh et al., 2008

Denitrifica=on •  In rice systems N fer=lizer is applied in

an ammonium (NH4) form or a fer=lizer that quickly turns to NH4.

•  When a field is flooded the N stays as NH4.

•  When a field is drained (or it remains in a unflooded condi=on) the NH4 turns to nitrate (NO3). Both NH4 and NO3 can be taken up by plants.

•  When a field is reflooded, the NO3 present in the soil can be lost as gas to the atmosphere.

•  We do NOT want fer=lizer N turning to NO3

O2 H+

Flood Water

Oxidized Zone

Reduced Zone

Urea Ammonium Sulfate

Fer;lizer Incorpora;on Zone

O2

NH3 ,N2O, N2

Urea Aqua-‐ammonia Ammonium Sulfate

NO3

Nitrate

NO3


Nitrogen: func=on and deficiencies

•  Func=on •  amino acids •  proteins •  chlorophyll •  enzymes •  DNA

•  Deficiency •  Yellow leaves-‐star=ng with lower leaves •  Reduced growth and =llering •  Do not confuse with S deficiency


Nitrogen: figuring out the rate

•  Factors affec=ng N rate – N source and placement –  Variety (not different for the main rice varie=es) –  Soil – Water management –  Climate –  Residue management

•  Incorpora=ng straw allows for a 25 lb/ac reduc=on in N input

•  BUT how do you know how much?


Rice yields versus N rate

Sheridan

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0 100 200 300Fertilizer N added (lb/ac)

Yiel

d (lb

/ac)

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A ll aqua

Only surface

A qua+surface

50 lb N


Rice yields versus N rate Arbuckle burn

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d (lb

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A ll aqua

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Arbuckle-Burn

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0 100 200 300Fertilzer N added (lb/ac)

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Arbuckle-Incorporated

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Determining the correct rate for your field

150

175 +25

125 -‐25

150

150

150

150

150

150

150

•  Representa=ve check •  One pass with +25 and

another pass with -‐25 –  Aqua rig vs. combine width

–  Flag each pass •  Monitor over season •  Determine yield with

yield monitor •  Do over years and

fields •  Keep records


N source and placement

Aqua-‐NH3 Aqua-‐NH3 + starter

versus


Rice yields versus N rate Arbuckle burn

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Yiel

d (lb

/ac)

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A ll aqua

Only surface

A qua+surface

Arbuckle incorporated

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/ac)

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d (lb

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A ll aqua

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Arbuckle-Burn

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0 100 200 300Fertilzer N added (lb/ac)

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d (lb

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A ll aqua

Only surface

A qua+surface

Arbuckle-Incorporated

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N source, placement, =ming

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Aqua+starter Aqua

Yield (lb

/ac)

a b •  Applying all N as aqua –  Increased N use efficiency –  Same yield poten=al –  At op=mal yields

•  Reduce N rate by 10 lb/ac –  Cheaper source of N –  Early growth (35 DAS) is slightly reduced in some loca=ons

Data: 7 field studies/100 lb N/ac N rate


Is a topdress necessary?

Total N N treatment 0 0-0

100 100-0 100 75-25 100 25-75 100 100 AS 150 150-0 150 112.5-37.5 200 200-0 200 150-50


Wet seeded conventional grain yield (14% moisture)

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0 50 100 150 200Total N applied (lb/ac)

Grain

yield

(lb/

ac)

m

All preflood

Split

Ammonium sulfate

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Grain yields (lb ac-‐1)

Total N applied (lb N ac-‐1)

2008

Preflood

Split

AS

Grower wet seeded no-till

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Total N applied (lb/ac)

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in y

ield

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ac)

m

All preflood

Split

Ammonium sulfate

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Grain yields (lb ac-‐1)

Total N applied (lb N ac-‐1)

Willows Preflood Split AS LSD = 1235


Is a topdress necessary?

•  When the same amount of N is applied, we have not yields being significantly higher with a topdress compared to when it is all applied as aqua.

•  Some say “When I topdress I get higher yields”. •  That may be because you simply applied more N. The real ques=on is would you have goien higher yields if you had applied that N as preplant?


N applica=ons following a herbicide applica=on

•  One month aqer plan=ng the soil s=ll has a lot of N –  Plants are small and N demand low

•  Addi=on of more N during this period will likely have limited impact on plant uptake.

1 mo afer plan;ng

1 mo afer plan;ng


Nitrogen source

•  When aqua is not an op=on


Nitrogen management: the 4Rs •  Right rate

–  Determined individually •  Right source

–  As much aqua-‐N as possible –  Lowest amount of N in starter as possible

•  Right place –  Injected 3-‐4 inches below soil surface

•  Right =me –  All N can be applied just before flooding

•  Excep=on: if you plan to apply P late

–  No benefit of planning a split N applica=on •  Apply if necessary •  Excep=on: planning for early season drain event

Phosphorus

•  Only 10% of rice soils P deficient •  Most growers apply P fer=lizer •  Deficiencies are developing


Phosphorus: func;on and deficiency

•  Func=on • Membrane integrity •  Energy storage •  Phloem transport

•  Deficiency •  Stunted dark green plants •  Narrow leaves •  Reduced =llering •  Symptoms oqen diminish with =me

•  Delayed flowering


•  Soil test – Olsen-‐P test (sodium-‐bicarbonate)

•  above 6-‐9 ppm – Bray-‐P test not good for CA rice soils

•  Plant =ssue test – Y-‐leaf =ssue test.

•  35 DAS •  0.2% P

•  Input-‐output P budget

Determining the soil P status


Input-‐output P budget •  Soil is P bank •  P is rela=vely immobile in soils.

– No gas losses –  Liile is lost through water –  Liile lost by leaching

•  Inputs –  Fer=lizer

•  Outputs – Grain removal (0.52% P2O5) –  Straw removal (0.21% P2O5)


Input-‐output P budget

•  Develop a budget –  Inputs (lb/ac of P2O5 as fer=lizer) – Outputs (lb/ac removed in

grain and straw)

– Develop such a budget over 5 yr period – take average


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-‐40.0 -‐20.0 0.0 20.0 40.0

Olsen

P (p

pm)

Annual P budget (lb P2O5/yr)

P management, soil P and P budget

•  Nega=ve budget = yield response

•  Olsen P reflects previous P mgmt.

•  Growers applied similar P rates

•  Difference: yield


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-‐40 -‐20 0 20 40

Olsen

P (p

pm)

Annual P budget (lb P2O5/yr)

Should you apply?

•  High P levels (above 15 ppm) / posi=ve P budget –  Apply no P

•  Low P soils (below 6 ppm) / nega=ve P budget –  Build up soil P

•  The rest: P not limi=ng –  Apply maintenance rate

•  that removed by crop


Amount of P removed: Only grain removed

Grain yield (cwt@14%)

P added/removed (lb P2O5/ac) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70

P balance (lb P2O5/ac) 50 -‐26 -‐21 -‐16 -‐11 -‐6 -‐1 4 9 14 19 24 29 34 39 44 55 -‐29 -‐24 -‐19 -‐14 -‐9 -‐4 1 6 11 16 21 26 31 36 41 60 -‐31 -‐26 -‐21 -‐16 -‐11 -‐6 -‐1 4 9 14 19 24 29 34 39 65 -‐34 -‐29 -‐24 -‐19 -‐14 -‐9 -‐4 1 6 11 16 21 26 31 36 70 -‐37 -‐32 -‐27 -‐22 -‐17 -‐12 -‐7 -‐2 3 8 13 18 23 28 33 75 -‐39 -‐34 -‐29 -‐24 -‐19 -‐14 -‐9 -‐4 1 6 11 16 21 26 31 80 -‐42 -‐37 -‐32 -‐27 -‐22 -‐17 -‐12 -‐7 -‐2 3 8 13 18 23 28 85 -‐44 -‐39 -‐34 -‐29 -‐24 -‐19 -‐14 -‐9 -‐4 1 6 11 16 21 26 90 -‐47 -‐42 -‐37 -‐32 -‐27 -‐22 -‐17 -‐12 -‐7 -‐2 3 8 13 18 23 95 -‐50 -‐45 -‐40 -‐35 -‐30 -‐25 -‐20 -‐15 -‐10 -‐5 0 5 10 15 20 100 -‐52 -‐47 -‐42 -‐37 -‐32 -‐27 -‐22 -‐17 -‐12 -‐7 -‐2 3 8 13 18 105 -‐55 -‐50 -‐45 -‐40 -‐35 -‐30 -‐25 -‐20 -‐15 -‐10 -‐5 0 5 10 15 110 -‐57 -‐52 -‐47 -‐42 -‐37 -‐32 -‐27 -‐22 -‐17 -‐12 -‐7 -‐2 3 8 13

Maintenance line

P budget calculator

P budget calculator

P budget calculator: Printout

When to apply:

•  Before plan=ng – Use P source with lowest N content –  Incorporate

•  Timing to control algae – Applica=on of P before plan=ng can lead to algae – Algae reduces crop density and growth



P management and algae control

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60

Grower 1 Grower 2

Algae dry weight (g/m2)

At plan=ng (on surface)

Spring applied (incorporated)

30 days aqer plan=ng •  Early applica=on and incorpora=on reduced algae 53% on average

•  Delayed applica=on decreased algae by 88% on average

When to apply: Grain yield response to delayed P applica=ons


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No P 0 14 28 42

Yield (cwt/ac)

P ;ming (days afer plan;ng)

b a a a a

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No P 0 14 28 42

Yield (cwt/ac)

P ;ming (days afer plan;ng)

b a ab ab c

Delayed P applica=on effects on water quality

Days after delayed P application0 5 10 15 20 25 30

Wat

er P

O4-

P (

mg

L-1)

0.0

0.5

1.0

1.5

2.0

Location ALocation BLocation CLocation DLocation E

slope = -‐0.054 mg L-‐1 d-‐1 (P = 0.029)intercept = 0.394 mg L-‐1 (P = 0.3489)

R2 = 0.87


Water release


Phosphorus management: the 4Rs

•  Right rate –  Based on soil test and P budget

•  Right source –  P fer=lizer with lowest N content

•  Right place –  Incorporated: when applied before flooding –  Broadcast: late applica=on into water

•  Right =me – Maintenance rates: flexibility –  Deficient soils: between land prep and 30 days aqer plan=ng –  Algae problems: aqer rice plants emerge (20-‐30 DAP)


Potassium: func=on •  Plant regula=on

– Osmoregula=on –  Enzyme ac=va=on –  Regula=on of cell pH –  Cellular ca=on-‐anion balance –  Regula=on of transpira=on –  Regula=on of assimilate transport

•  Inadequate K results in: – Adequate K improves a plants ability to tolerate adverse clima=c condi=ons, lodging, insects, and diseases.


Potassium: deficiency •  Older leaf =ps are yellowish

brown •  Younger leaves can be

short and droopy •  Rusty brown spots appear

on =ps of older leaves and then spreads to en=re leaf.

•  Symptoms tend to appear during later growth stages.

•  An accumula=on of sugars and amino acids that are suitable food sources for leaf diseases


Potassium and aggregates sheath-‐spot (AgSS)

y = -0.65x + 3.39R2 = 0.58

2.00

2.20

2.40

2.60

2.80

3.00

1.00 1.20 1.40 1.60 1.80 2.00

Midseason leaf K concentration (% )

AgS

S ra

ting

c

Incorporated

Removed

Flag leaf K vs. soil K Flag leaf K vs soil K

0.80

1.00

1.20

1.40

1.60

1.80

2.00

2.20

0 60 120 180 240 300 360 420

Flag leaf K con

centra;o

n (%

)

Soil K (ppm)

50% 24%


Potassium: loca=ons of low K soils

•  East side of valley •  Related to soils and irriga=on water

>120 ppm 100-‐120 ppm 60-‐100 ppm <60ppm

Stage Plant Leaf 1

2

3

4

5

Tillering begins

Maximum ;llering

Panicle ini;a;on* Heading R7 Maturity

Fer=lity program for water-‐seeded rice

Starter blend (NPK w/ lowest

amount of N possible)

Aqua-‐N applica;on

Access need for topdress N

applica;on at PI (use urea or AS if needed)

OR before 28 DAS


Nutrient management adjustments for different systems

•  Drill-‐seeded systems •  Stale-‐seed bed systems


Drill seeded rice •  Right rate

–  Similar to water-‐seeded rice for all nutrients

•  Right source –  Urea plus a starter blend

with P and K if necessary •  Right place

–  Surface applied •  Right =me

–  Just before permanent flood –  No benefit of applying a

por=on of N rate at plan=ng.


Stale seedbed systems

•  Stale seedbed – Flush of water to bring up weeds may also increase NO3 accumula=on before flooding

•  No-‐=ll – Fer=lizer needs to be applied on the surface


Stale seedbed systems •  Right rate

–  Water seeded-‐increase N rate by 30 lb N/ac. –  Drill seeded-‐no change to N rate

•  Right source –  Urea plus a starter blend with P and K if necessary

Water-seeded

N rate (lb ac-1)

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Gra

in yie

ld (l

b ac

-1)

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4000

6000

8000

10000

WS conventionalWS staleWS no-till stale

Drill-seeded

N rate (lb ac-1)

0 50 100 150 200

DS conventionalDS no-till stale

•  Right place –  Surface applied

•  Right =me –  Water seeded

•  Just before flooding

–  Drill-‐seeding •  Just before

permanent flood

1. 2. 3. 4. 5. 6.

2%0%

27%

13%10%

48%

Enter ques=on text...

1.  Aqua-‐NH3 2.  Ammonium sulfate 3.  UAN-‐32 (urea-‐

ammonium nitrate) 4.  Urea 5.  Ammonium

phosphate 6.  All the above are

suitable

Clicker ques=on

What is not a suitable N fer=lizer source for flooded rice systems?


1. 2. 3. 4.

0%8%

90%

2%


1.  Draining the field is not a problem

2.  Draining field reduces root growth and reduces N uptake

3.  Draining the field results in ammonium (NH4-‐N) being converted to nitrate (NO3-‐N) which is suscep=ble to loss when the field is reflooded

4.  A large amount of N is lost in the tailwater when the flood water is drained from the field


Clicker ques=on From a nitrogen management perspec=ve, why is draining the field early in the season a problem?

1. 2. 3. 4. 5.

13%

19% 19%

50%

0%


1.  Before plan=ng 2.  4 weeks aqer

plan=ng 3.  6 weeks aqer

plan=ng 4.  1 & 2 above 5.  All the above

Clicker ques=on

When are safe =mes to apply P without risk of yield loss?


1. 2. 3.

30%

40%

30%


1.  Nitrogen (N) 2.  Phosphorus (P) 3.  Potassium (K)

Clicker ques=on

Removing rice straw (i.e. bailing) removes the most of which nutrient?



THANK YOU

Ques=ons?


Nitrogen management: Straw management effects

•  Yield poten=al is the same •  Incorpora=ng rice straw affects op=mum N rate

–  IF incorporated during winter: Fer=lizer N rates can be reduced by 25 lb/ac without compromising yield under straw incorpora=on

–  IF leq on surface/standing with no flood: Fer=lizer rates may need to be increased

Yie

ld lb

s/ac

re (1

4% m

oist

ure)

No Flood Winter Flood

Figure 4. Yield of rice grain Maxwell 2000, after 7 seasons of alternative strawmanagement practices.

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10000

12000

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BurnedIncorporated

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t 14%

moi

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e

Documents

Bruce&Linquist UCDavis,Dept.PlantSciences