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No-till on the Plains Salina, KS January 26-27, 2004. Sustainable Nutrient Use Efficiency In No-Till Systems Paul Fixen Senior Vice President Potash & Phosphate Institute. Sustainable nutrient use efficiency (NUE) in no-till systems. Why the increased emphasis on NUE? Definition of NUE

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No till on the plains salina ks january 26 27 2004

No-till on the PlainsSalina, KS January 26-27, 2004

Sustainable Nutrient Use Efficiency In No-Till Systems

Paul Fixen

Senior Vice President

Potash & Phosphate Institute


Sustainable nutrient use efficiency nue in no till systems
Sustainable nutrient use efficiency (NUE) in no-till systems

  • Why the increased emphasis on NUE?

  • Definition of NUE

  • Sustainable NUE

  • Special considerations for no-till

  • So what? … What does this mean to me?


Why the emphasis on nue
Why the emphasis on NUE?

  • Input costs are increasing

    • U.S. natural gas prices will remain higher than traditional levels … N prices will as well

  • Increasing pressure to minimize negative environmental impacts

    • Global, national, state, and local levels

    • Water and air quality concerns

  • Government incentive programs encouraging practices that increase NUE

  • Development and promotion of products that promise increased NUE


Nutrient use efficiency functional definitions
Nutrient use efficiency functional definitions

  • Recovery efficiency = Increase in uptake by the plant per unit nutrient added usually expressed as %

  • Example:

N uptake when no N applied = 30 lb/A

N uptake when 100 lb applied = 90 lb/A

(90-30)/100 = 60% recovery

  • Agronomic efficiency (AE) = Crop yield increase per unit nutrient added usually expressed as bu/lb

  • Example:

Corn yield = 150 bu/A

N applied = 100 lb/A

150/100 = 1.5 bu/lb


Agronomic efficiency of fertilizer n used on corn grain in the u s 1964 2002

39% increase in agonomic efficiency

12% increase in N fertilizer use

40% increase in corn yields

Since 1975:

Agronomic efficiency of fertilizer N used on corn grain in the U.S., 1964-2002

Recovery efficiency often

less than 50%

1.06

0.76


Effect of p on agronomic use efficiency of n on irrigated corn
Effect of P on agronomic use efficiency of N on irrigated corn

MEY: 186 bu/A

MEY N rate: 159 lb/A

Agron effec= 1.17

bu/lb

MEY: 129 bu/A

MEY N rate: 145 lb/A

Agron effec = 0.89 bu/lb

Kansas; 30-year mean

Source: Schlegel et al., 1996


Balanced nutrition increases N recovery efficiency corn

  • Kansas State University – irrigated corn

    • No P applied 35% N recovery

    • 40 lb P2O5/A 75% N recovery



Is maximum nue our goal1
Is maximum NUE our goal? corn

MEY: 186 bu/A

MEY N rate: 159 lb/A

Agron effec = 1.17

bu/lb

Yield: 134 bu/A

N rate: 40 lb/A

Agron effec = 3.35 bu/lb

Kansas; 30-year mean

Source: Schlegel et al., 1996


Is maximum nue our goal2
Is maximum NUE our goal? corn

  • No

  • Nutrient use should be efficient and effective

    • Effective – accomplishes the objectives of nutrient use

      • Meets production needs for yield and quality

      • Optimizes profitability

      • Sustains soil, water and air quality

        • Where N separates from P and K

  • Sustainable NUE incorporates the elements of effectiveness … our goal


Agronomic efficiency and soil test p

Garcia, 2002 corn

Relative yield, %

Agronomic efficiency and soil test P


N vs p recovery efficiency and issues

Nitrogen: Good 1 cornst yr

recovery is 60%

Phosphorus: Good 1st yr

recovery is 20%

  • 40% unrecovered

  • Potential fate

    • Part of soil OM or resid. NO3-

    • Lost in runoff or erosion

    • Volatilized from soil or plants

    • Leached below root zone

    • Denitrified to air

  • Losses can be large

  • 80% unrecovered

  • Potential fate

    • Part of soil OM

    • Lost in runoff or erosion

    • Fixed as unavailable P

    • Contribute to soil test P – vast majority

  • Losses usually minor

N vs P recovery efficiency and issues


Residual effects of a single p application over a 14 year period
Residual effects of a single P application over a 14-year period

Check tested 17 ppm in fall of 1975 when P was applied.

Webb et al., 1992


Examples of apparent recovery efficiency of p fertilizer in long term studies
Examples of apparent recovery efficiency of P fertilizer in long term studies

GH = Green house; F = Field.

Fixen, 1992


The primary cause of low short term recovery of p fertilizer

The primary cause of low short term recovery of P fertilizer long term studies

the inability of P to move to absorbing roots


Spring wheat roots at 38 days based on average root density in surface 6

Root long term studies

0.12”

0.5”

P diffusion zone

Distance between roots

Spring Wheat Roots at 38 Daysbased on average root density in surface 6”

5% of soil volume can

contribute P to the plant


Spring wheat roots at 94 days based on average root density in surface 6

0.24” long term studies

Distance

between

roots

Spring Wheat Roots at 94 Daysbased on average root density in surface 6”

Root

0.13”

P diffusion

zone

26% of soil volume can

contribute P to the plant


Mycorrhizae an efficiency enhancing fungus encouraged by no till systems

  • Produce glomalin long term studies

    • A major form of stable OM

    • Stabilizes soil aggregates

    • Sequesters carbon

Mycorrhizae … an efficiency enhancing fungus encouraged by no-till systems

  • Increases the “reach” of plant roots

  • Decline with increasing P fertility, tillage

S. Wright, ARS


Where short term recovery is most critical
Where short term recovery is most critical long term studies

  • Short land tenure

  • Limited operating capital and sub-optimal soil test levels

  • Soils with severe P fixing potential (rare in Plains and Midwest)

  • Threat to water quality


Broadcast successive banding vs successive banding only
Broadcast + successive banding vs. long term studiessuccessive banding only

Amount broadcastinitially, lb P2O5/A

110

160

100

0

90

Relative yield,percent of maximum

80

70

5-yr averages

60

0

10

20

30

40

Annual rate of seed placed P, lb P2O5/A

Wager et al., 1986


Sustainable nue for p brings the management focus to soil test p and your nutrient budget
Sustainable NUE for P brings the management focus to long term studiessoil test P and your nutrient budget

  • Define a target P level based on:

    • Local calibration data, land tenure, etc.

  • If current level is less than target

    • Rate should exceed removal

  • If current level is greater than target

    • Rate should be less than removal


Partial p budget for kansas average of 1998 2000
Partial P budget for Kansas long term studies(average of 1998-2000)

1 Potash & Phosphate Institute (using 0.35 lb P2O5 /bu of corn).

2 Terry and Kirby, 2000, 2001. 3 NRCS, (1997 production).


Percent of soils testing medium or lower in p 2001
Percent of soils testing medium or lower in P (2001) long term studies

Ratio of P removal by crops to fertilizer + manure P use

Ratio of P removal by crops to fertilizer use

AB

AB

AB

MB

MB

MB

1.15

0.90

SK

SK

SK

59

1.36

1.27

86

73

0.98

0.86

78

MT

MT

MT

1.24

1.21

1.10

1.06

ND

ND

ND

78

69

1.69

1.41

SD

SD

SD

0.68

WY

WY

WY

58

0.79

59

1.63

1.16

NE

NE

NE

CO

CO

CO

1.80

1.03

60

46

1.48

1.10

KS

KS

KS

1.17

0.82

OK

OK

OK

NM

NM

NM

68

57

1.69

0.90

TX

TX

TX

0.86

0.56

59


Know your nutrient budgets
Know your nutrient budgets long term studies

  • Inputs: yield history, fertilizer history, manure history

  • Subtract removal from nutrient additions = balance

  • Calculations can be done by hand or with software

    • Example: PKalc

www.ppi-ppic.org/toolbox


Evaluation of new products promising increased nue
Evaluation of new products promising increased NUE long term studies

  • Be skeptical

    • What’s the mechanism?

    • University data … not just testimonials

    • Do the arithmetic – NO FREE LUNCH

      • Is it simply mining soil nutrients which will eventually need replacement

  • But … be open minded

    • Some new products do look promising

    • Test on small acreage with check strips


For 140 bu/A corn long term studies

lb P2O5/A

Sufficiency

approach

4-year build

approach

New KSU recommendations offer range of build targets and build rates because these are farmer specific

  • Target level and rate of build depends on:

    • Risk management

    • Land tenure

    • Within-field variability

    • Capital supply

Crop removal = 46 lb


Influence of no till on target soil test levels
Influence of no-till on target soil test levels long term studies

  • Phosphorus

    • Highly stratified with depth

    • Has rarely caused problems

    • No adjustment in target levels

  • Potassium

    • Also stratified with depth

    • Has resulted in availability problems

    • Target soil test levels could be higher unless subsurface placement is used


Interaction between population and nutrient management for irrigated ridge till corn in kansas

Cause of response long term studies

Based on drop-out treatments

Interaction between population and nutrient management for irrigated ridge-till corn in Kansas

1 Plus 230 lb N/A with 2 splits (preplant, V4).

2 KSU recommendation.

Carr site Bray P1 = 20 ppm, K = 240 ppm

Crete site Bray P1 = 25 ppm, K = 180 ppm.

High yield systems under

reduced tillage may have

higher soil test level requirements

Gordon (KSU), 2004


Optimum placement and timing the traditional focus of managing for high nue
Optimum placement and timing … the traditional focus of managing for high NUE

  • For N, always important (along with getting the rate right)

  • For P (and K)

    • Most important at low soil test levels

    • Higher the soil test levels, the greater the flexibility in placement

    • Localized band applications may be important for “starter” effects on crops such as corn or wheat independent of impacts on NUE

      • Insurance against sub-optimal soil test levels and within field variability

      • Reduces the negative impact of growing season limitations

      • Protection against variety-specific weaknesses


What does this mean to me
What does this mean to me? managing for high NUE

  • Incentives are increasing for efficient and effective nutrient use … sustainable nutrient use effciency

    • Good time to review nutrient management practices

  • Efficiency is influenced by nutrient balance … paying attention to all needed nutrients (soil testing, plant analysis, local research)

  • The focus for N efficiency should be on 1st year results

  • Managing for efficient P use (and K) is best accomplished when a longer time horizon is considered

    • Establish and maintain target soil fertility levels

    • Consider the impact of practices on future productivity as well as 1st year results


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