Sustainable Nutrient Use Efficiency In Sustainable Nutrient Use Efficiency In No-Till SystemsNo-Till Systems

Paul FixenPaul FixenSenior Vice President Senior Vice President

Potash & Phosphate InstitutePotash & Phosphate Institute

No-till on the PlainsNo-till on the PlainsSalina, KS Salina, KS

January 26-27, 2004January 26-27, 2004

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

Why the increased emphasis on NUE?

Definition of NUE

SustainableSustainable NUE

Special considerations for no-till

So what? … What does this mean to me?

Why the emphasis on NUE?

Input costsInput 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 impactsenvironmental impacts

Global, national, state, and local levels

Water and air quality concerns

Government incentive programsGovernment incentive programs encouraging practices that increase NUE

Development and promotion of productsDevelopment and promotion of products that promise increased NUE

Nutrient use efficiency functionalfunctional definitions

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

Example:Example: N uptake when no N applied = 30 lb/AN uptake when 100 lb applied = 90 lb/A(90-30)/100 = 60% recovery60% recovery

Corn yield = 150 bu/AN applied = 100 lb/A150/100 = 1.5 bu/lb1.5 bu/lb

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

• Example:Example:

0.50.60.70.80.91.01.11.21.31.4

1960 1965 1970 1975 1980 1985 1990 1995 2000

bu p

er lb

of N

.

0.760.76

1.061.06

39% increase in agonomic efficiency12% increase in N fertilizer use

40% increase in corn yieldsSince 1975:

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

Recovery efficiency often Recovery efficiency often less than 50%less than 50%

60

80

100

120

140

160

180

200

0 20 40 60 80 100 120 140 160 180 200

N rate, lb/A

Yie

ld, b

u/A

with P

without P

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

MEY: 129 bu/A MEY N rate: 145 lb/AAgron effec = 0.89 bu/lb

Source: Schlegel et al., 1996

Kansas; 30-year mean

MEY: 186 bu/AMEY N rate: 159 lb/AAgron effec= 1.17 bu/lb

Kansas State University – irrigated corn No P appliedNo P applied 35% N recovery35% N recovery 40 lb P40 lb P22OO55/A/A 75% N recovery75% N recovery

Balanced nutrition increases N Balanced nutrition increases N recovery efficiencyrecovery efficiency

Is maximum NUE our goal?

60

80

100

120

140

160

180

200

0 20 40 60 80 100 120 140 160 180 200

N rate, lb/A

Yie

ld, b

u/A

with P

without P

Is maximum NUE our goal?

Source: Schlegel et al., 1996

Kansas; 30-year mean

MEY: 186 bu/AMEY N rate: 159 lb/AAgron effec = 1.17 bu/lb

Yield: 134 bu/AN rate: 40 lb/AAgron effec = 3.35 bu/lb

Is maximum NUE our goal?

NoNo Nutrient use should be efficient and effectiveand effective

EffectiveEffective – accomplishes the objectives of nutrient use Meets production needs for yieldyield and qualityqualityOptimizes profitabilityprofitability SustainsSustains soil, water and air quality

Where NN separates from P and KP and K

Sustainable NUE Sustainable NUE incorporates the elements of effectiveness … our goal

(lb

wh

eat/

lb a

pp

lied

P)

(lb

wh

eat/

lb a

pp

lied

P)

Garcia, 2002

30

40

50

60

70

80

90

100

0 7 13 20 27Soil Bray P (ppm)

Re

lati

ve

yie

ld,

%

Winter wheat, Kansas

30

40

50

60

70

80

90

100

0 7 13 20 27Soil Bray P (ppm)

Re

lati

ve

yie

ld,

%

Winter wheat, Kansas

(lb

wh

eat/

lb a

pp

lied

P)

(lb

wh

eat/

lb a

pp

lied

P)

Rel

ativ

e yi

eld,

%

Agronomic efficiency and soil test P

N vs P recovery efficiency and issues

Nitrogen: Good 1Nitrogen: Good 1stst yr yr recovery is 60% recovery is 60%

• 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 largelarge

Phosphorus: Good 1Phosphorus: Good 1stst yr yrrecovery is 20%recovery is 20%

• 80% unrecovered• Potential fate

• Part of soil OM• Lost in runoff or erosion• Fixed as unavailable P• Contribute to soil test P –Contribute to soil test P – vast majority vast majority

• Losses usually minorminor

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

lb P2O5/A lb P2O5/A

Year 0 298 0 298

Bray P1, ppm Corn yield, bu/A Resp.

1977 13 36 134 135 11

1980 9 24 158 170 1212

1983 6 14 120 147 2727

1986 7 15 117 158 4141

1989 4 8 123 143 1919

MeanMean 133133 153153 2020

Webb et al., 1992

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

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

Soil(s) Applied No. of Recovery

P2O5, kg/ha Crops %

Calcareous clay 67 5 F 28

Clay loam, pH 7.3 29 9 F 54

28 soils, pH 6.2-7.9 152 8 GH 74

4 soils, pH 6.7-7.6 230 19 GH 87

Sandy loam, non-calcareous 118 4 F 100

GH = Green house; F = Field.GH = Green house; F = Field.

Fixen, 1992

The primary cause of low short term recovery of P fertilizer

the inability of P to move to absorbing roots

0.12”0.12”P diffusion zoneP diffusion zone

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

RootRoot

0.5”0.5”Distance between rootsDistance between roots

5%5% of soil volume can of soil volume can contribute P to the plantcontribute P to the plant

0.13”0.13”P diffusion P diffusion

zonezone

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

RootRoot0.24”0.24”

Distance Distance between between

rootsroots

26%26% of soil volume can of soil volume can contribute P to the plantcontribute P to the plant

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

Produce glomalin

A major form of stable OM Stabilizes soil aggregates Sequesters carbon

sporehyphae

Green = glomalin

sporehyphae

Green = glomalin

Where short term recovery is most critical

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

60

70

80

90

100

110

0 10 20 30 40

Annual rate of seed placed P, lb P2O5/A

Re

lati

ve

yie

ld,

pe

rce

nt

of

ma

xim

um 160

0

Broadcast + successive banding vs.successive banding only

Amount broadcast initially, lb P2O5/A

Wager et al., 1986

5-yr averages

Sustainable NUE for P brings the management focus to soil test P soil test P and your nutrient budget 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)

1 Potash & Phosphate Institute (using 0.35 lb P2O5 /bu of corn).2 Terry and Kirby, 2000, 2001. 3 NRCS, (1997 production).

Crop Applied Recov. Removal to use

removal1 fertilizer2 manure3 FertilizerFert. + manure

------- P2O5, million lbs ------

631 427 149 1.48 1.10

NDND

SKSKMBMBABAB

MTMT

SDSD

WYWY

NMNM

NENE

KSKS

OKOK

TXTX

COCO

7373

5959

6868

60605959

7878 7878

6969

5959 8686

5858

4646

5757

NDND

SKSKMBMBABAB

MTMT

SDSD

WYWY

NMNM

NENE

KSKS

OKOK

TXTX

COCO

0.980.98

0.860.86

1.171.17

1.481.48

1.631.63

1.101.10 1.241.24

1.691.69

1.151.151.361.36

0.790.79

1.801.80

1.691.69

Ratio of P removal by crops

to fertilizer use

Ratio of P removal by crops

to fertilizer + manure P use

NDND

SKSKMBMBABAB

MTMT

SDSD

WYWY

NMNM

NENE

KSKS

OKOK

TXTX

COCO

0.860.86

0.560.56

0.820.82

1.101.10

1.161.16

1.061.06 1.211.21

1.411.41

0.900.901.271.27

0.680.68

1.031.03

0.900.90

Percent of soils testing medium or lower in P (2001)

Know your nutrient budgets

Inputs: yield history, fertilizer history, manure history Subtract removal from nutrient additions = balancebalance Calculations can be done by hand or with software

Example: PKalc

www.ppi-ppic.org/toolboxwww.ppi-ppic.org/toolbox

Evaluation of new products promising increased NUE

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

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

For 140 bu/A cornlb P2O5/A

Sufficiencyapproach

4-year buildapproach

Crop removal = 46 lbCrop removal = 46 lb

Target level and rate of Target level and rate of build depends on:build depends on:

• Risk management• Land tenure• Within-field variability• Capital supply

Influence of no-till on target soil test levels

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

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.

P2O5+K2O+S, lb/A1

Population 30+0+02 100+80+40 Response

PPA grain yield, bu/A

Carr sandy loam, avg of 2000-2002

28,000 162 205 43

42,000 159 223 64

Crete silt loam, 2003

28,000 176 203 27

42,000 174 247 72

Cause of response

Based on drop-out treatments

%

12318S

155042K

832640P

200320022001Nutrient

Year

%

12318S

155042K

832640P

200320022001Nutrient

Year

Gordon (KSU), 2004

High yield systems underHigh yield systems underreduced tillage may havereduced tillage may have

higher soil test level requirementshigher soil test level requirements

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

For N, always important (along with getting the raterate right) For P (and K)

Most important at low soil test levelslow soil test levels Higher the soil test levels, the greater the flexibilityflexibility in

placement Localized band applications may be important for “starterstarter”

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?

Incentives are increasing for Incentives are increasing for efficientefficient and and effectiveeffective nutrient use … sustainable nutrient use effciencynutrient use … sustainable nutrient use effciency Good time to review nutrient management practicesGood time to review nutrient management practices

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

The focus for The focus for N efficiencyN efficiency should be on should be on 11stst year results year results Managing for efficient P use (and K) is best Managing for efficient P use (and K) is best

accomplished when a accomplished when a longer time horizonlonger time horizon is considered is considered Establish and maintain Establish and maintain target soil fertility levelstarget soil fertility levels Consider the impact of practices on Consider the impact of practices on future productivityfuture productivity as as

well as 1well as 1stst year results year results