Tillage and Fertility Tillage and Fertility Opportunities and Opportunities and

Challenges Challenges

Dick WolkowskiDick WolkowskiDepartment of Soil ScienceDepartment of Soil Science

UW-MadisonUW-Madisonrpwolkow@wisc.edurpwolkow@wisc.edu

Today’s potpourri of issuesToday’s potpourri of issues

Vertical tillage/subsoilingVertical tillage/subsoiling

Crop residue management Crop residue management alternativealternative

Fertilizer placementFertilizer placement

Foliar feedingFoliar feeding

Vertical tillageVertical tillageDefined as deep tillage designed to create Defined as deep tillage designed to create vertical zones by cutting a slot, shattering, and vertical zones by cutting a slot, shattering, and lifting the soillifting the soil– Minimal inversionMinimal inversion– Prepares seedbedPrepares seedbed– Various spacingsVarious spacings– Fall or springFall or spring

What is the motive for deep tillageWhat is the motive for deep tillage– Part of a system associated with crop management Part of a system associated with crop management

programs, e.g. Zone-tillprograms, e.g. Zone-tillTMTM, ProfitPro, ProfitProTM TM

Compaction not diagnosedCompaction not diagnosed

– Response to poor soil condition (aka subsoiling)Response to poor soil condition (aka subsoiling)Compaction diagnosedCompaction diagnosed

““Vertical tillage” implementsVertical tillage” implements

Are all situations responsive to deep Are all situations responsive to deep tillage? tillage? Soil bulk density profile, Arlington, Soil bulk density profile, Arlington,

Wis., 1998Wis., 1998

0.8 - 0.90.9 - 11 - 1.11.1 - 1.21.2 - 1.31.3 - 1.4

Not subsoiled

Subsoiled

Bulk Density (g/cc)

PLANO SILT LOAM

R R

RR

0

8

16

0

8

16

Depth (in)

EFFECT OF TILLAGE AND K FERTILIZATION ON FIRST-YEAR EFFECT OF TILLAGE AND K FERTILIZATION ON FIRST-YEAR CORN YIELD AFTER SOYBEAN (2 yr. avg.)CORN YIELD AFTER SOYBEAN (2 yr. avg.)

50

100

150

200

250

NONE SUBSOIL CHISEL

YIE

LD

(b

u/a

)

NONE 50 lb K2O 100 lb K2O

Arlington, Wis.

Soil abuse that causes Soil abuse that causes compaction is all too commoncompaction is all too common

Deep tillage can be beneficial Deep tillage can be beneficial where compaction is where compaction is

diagnoseddiagnosed

First: ID depthand strengthof compaction

Sunflower tool used in Hancock deep Sunflower tool used in Hancock deep tillage study, 2003tillage study, 2003

Cone index in a potato hill as affected by Cone index in a potato hill as affected by compaction and deep tillage, Hancock, Wis.compaction and deep tillage, Hancock, Wis.

0

5

10

15

20

25

30

35

40

45

50

0 0.5 1 1.5 2 2.5

Cone Index (MPa)

Dep

th (

cm)

Series1

Series2

Series3

Series4

N/NN/YY/NY/Y

Compacted/Subsoiled

Plainfield loamy sandCompacted 15 April, 2x

Deep Till. Yield (cwt/a) No 373 Yes 398

There are differences There are differences between subsoilersbetween subsoilers

“V-Ripper”- Leading disks- Parabolic shanks- Winged points

“Conservation”- Cutting coulters- Straight shanks- Horizontal points

EFFECT OF SUBSOILER TYPE ON EFFECT OF SUBSOILER TYPE ON SOYBEAN AND CORN YIELD ON A SOYBEAN AND CORN YIELD ON A

SILTY CLAY LOAM SOILSILTY CLAY LOAM SOIL

20

25

30

35

40

45

50

55

60

1997 1999

YIE

LD

(b

u/a

)

NO-TILL V-RIPPER STRAIGHT

160

170

180

190

200

210

220

230

1998 2000

YIE

LD

(b

u/a

)

Manitowoc, Wis.

Soybean Corn

Compacted soils are responsive to K Compacted soils are responsive to K fertilizationfertilization

0

5

10

15

20

25

30

35

< 5 t 19 t

YIEL

D R

ESPO

NSE

(bu/

a)

OPTIMUM

V. HIGH

3 yr. avg.Oshkosh, Wis.

SOIL TEST K

8

9

10

11

12

< 5 t 14 t

YIEL

D (t

DM/a

)

OPT HIGH V. HIGH

SOIL TEST K

Sum of 3 hay yearsArlington, Wis.

Corn response to 45 lb K20/a in row

Alfalfa response to soil test K

DETERMINING THE NEED FOR SUBSOILING

• Evaluate depth and severity of compaction• Check with penetrometer, probe, shovel• Dig plants to examine roots• Leave untreated strips for comparison• Subsoiling is an expensive operation• Subsoiling is not a cure-all, address

compaction

OTHER SUBSOILING CONSIDERATIONSOTHER SUBSOILING CONSIDERATIONS

• Burial of crop residue• Destruction of natural channels• Sidewall smearing• May bring stones, clay, infertile soil

to the surface• Does not address compaction cause

Crop Residue Management: Crop Residue Management: Regional trend for more CTRegional trend for more CT

Eight Midwestern states:Eight Midwestern states:– 106 million acres of cropland106 million acres of cropland– 37 percent of all U.S. cropland37 percent of all U.S. cropland

46% of no-till acres in U.S. in the Midwest 46% of no-till acres in U.S. in the Midwest

2002 Midwest data2002 Midwest data– 17 million acres of no-till soybeans 17 million acres of no-till soybeans – 7 million acres of no-till corn 7 million acres of no-till corn – Forty-five million acres (42.5 %) used Forty-five million acres (42.5 %) used

conservation tillage conservation tillage

CTIC Website (2002 data)

Wisconsin behind regional Wisconsin behind regional trendtrend

0

10

20

30

40

50

60

70

Corn Soybean Forage

% o

f A

crea

ge

NT

MT

RT

CT

CTIC Website (2002 data)

Tillage has a measurable effect Tillage has a measurable effect on the soil conditionon the soil condition

Direct or interactive effectsDirect or interactive effectsPhysicalPhysical– Residue modifies temperature and Residue modifies temperature and

moisturemoisture– Consolidation vs. looseningConsolidation vs. loosening

ChemicalChemical– Nutrient and pH stratification Nutrient and pH stratification

BiologicalBiological– C distribution C distribution – N transformations N transformations

Soil temperature affected by Soil temperature affected by tillage and crop residuetillage and crop residue

0

5

10

15

20

25

30

11-Apr 18-Apr 24-Apr 2-May 9-May 16-May 23-May

DE

GR

EE

C

STRIP-TILLCHISELNO-TILL

2 " DEPTHMEASURED 4:00-5:00 PMEffect on in-row soil

temperature,Arlington, 1994

0

20

40

60

80

100

Res

idue

(%

)

Chisel

Strip- till

No- till

Effect on cropresidue,Arlington, 1994

Effects of long-term tillage on the Effects of long-term tillage on the plow layer pore size distribution plow layer pore size distribution

0

0.02

0.04

0.06

0.08

0.1

0.12

>150 150-15 15-1.5 1.5-0.3 0.3-0.1

Pore Size

MB

NT

Hill et al., 1985

Pore

volu

me (

cm3/c

m3)

Fertilizer placement affects corn root Fertilizer placement affects corn root distribution (0-6 in.)distribution (0-6 in.)

Root length (km/mRoot length (km/m33))

TillageTillage Fert. Fert. placementplacement

RowRow Untracked Untracked Inter-rowInter-row

Tracked Tracked Inter-rowInter-row

CHCH ROWROW 17.117.1 3.03.0 0.80.8

CHCH INTER-ROWINTER-ROW 12.012.0 4.44.4 1.41.4

NTNT ROWROW 19.819.8 2.52.5 0.80.8

NTNT INTER-ROWINTER-ROW 10.810.8 6.16.1 1.51.5

Kaspar et al., 1991

Controlled traffic is a key to Controlled traffic is a key to making reduced tillage workmaking reduced tillage work

Controlled traffic Controlled traffic research, Australiaresearch, AustraliaPracticed on 2.5 Practiced on 2.5 million acresmillion acres500 GPS guided 500 GPS guided tractorstractorsResearch shows Research shows 10-15% yield 10-15% yield increase from increase from controlled traffic controlled traffic

Strip tillage expands crop Strip tillage expands crop residue managementresidue management

Three categoriesThree categories ROW OR RESIDUE CLEARINGROW OR RESIDUE CLEARING

REMOVE RESIDUEREMOVE RESIDUE FINGER COULTERS, BRUSHES, SWEEPSFINGER COULTERS, BRUSHES, SWEEPS

STRIP TILLAGE (SHALLOW: < 6 in.)STRIP TILLAGE (SHALLOW: < 6 in.) MOVE RESIDUE, SEEDBED PREP., ROW FERTILIZERMOVE RESIDUE, SEEDBED PREP., ROW FERTILIZER FLUTED COULTERS, DISCSFLUTED COULTERS, DISCS

STRIP TILLAGE (DEEP: > 6 in.)STRIP TILLAGE (DEEP: > 6 in.) DISRUPT COMPACTION, DEEP-PLACE FERTILIZERDISRUPT COMPACTION, DEEP-PLACE FERTILIZER KNIVES KNIVES SOME WITH COULTERS TO MOVE RESIDUE OR CREATE SOME WITH COULTERS TO MOVE RESIDUE OR CREATE

MINI-RIDGESMINI-RIDGES

Tillage and P and K availabilityTillage and P and K availability

Possible issuesPossible issues

Nutrient stratificationNutrient stratification– Surface applied Surface applied

nutrientsnutrients– Crop residuesCrop residues– Vertical and horizontalVertical and horizontal

How to collect a How to collect a representative samplerepresentative sample

Fertilizer placement Fertilizer placement considerationsconsiderations

Soil test stratification following five Soil test stratification following five years of tillage management, Arlington, years of tillage management, Arlington,

Wis.Wis.

0 10 20 30 40 50 60 70

NT

CH

SOIL TEST P (ppm)

0 25 50 75 100 125 150 175 200

NT

CH

SOIL TEST K (ppm)

6-8" 4-6" 2-4" 0-2"

5 5.5 6 6.5 7

NT

CH

SOIL pH

Wolkowski, 2003 (Corn/soybean rotation)

Reduced tillage is more Reduced tillage is more responsive to fertilizationresponsive to fertilization

Positional availabilityPositional availability– Surface vs. sub-surfaceSurface vs. sub-surface– Wheel track vs. non-wheel track effects Wheel track vs. non-wheel track effects

on root distributionon root distribution

Reduced P and K fixation by the soilReduced P and K fixation by the soil

Reduced K uptake from zones of poor Reduced K uptake from zones of poor aerationaeration

Complete starter material Complete starter material recommendedrecommended

INTERACTIVE EFFECT OF TILLAGE AND ROW INTERACTIVE EFFECT OF TILLAGE AND ROW FERTILIZER, ARLINGTON, 1994-1996FERTILIZER, ARLINGTON, 1994-1996

140

150

160

170

180

FZ SZ CH NT

TI LLAGE

YIE

LD (b

u/a)

NONE

FS

FZ

2x2

CCCC SbCSbC

CHCH STST NTNT CHCH STST NTNT

------- % -------------- % ------- ------- % -------------- % -------

NONENONE 2.232.23 2.372.37 2.352.35 1.651.65 1.31.344

1.41.400

BDCTBDCT 2.352.35 2.192.19 2.512.51 2.512.51 2.12.188

1.41.400

2 x 22 x 2 2.852.85 3.263.26 2.312.31 2.462.46 2.52.588

2.12.166

EFFECT OF ROTATION, TILLAGE, AND FERTILIZER ON EFFECT OF ROTATION, TILLAGE, AND FERTILIZER ON TISSUE K CONCENTRATION 45 DAP, ARLINGTON, TISSUE K CONCENTRATION 45 DAP, ARLINGTON,

WIS., 2001WIS., 2001

Wolkowski, 2003

RESPONSE OF CORN TO TILLAGE AND FERTILIZER RESPONSE OF CORN TO TILLAGE AND FERTILIZER PLACEMENT, ARLINGTON, WIS. 2001-2003PLACEMENT, ARLINGTON, WIS. 2001-2003

140

160

180

200

220

CH ST NT CH ST NT

Yie

ld (

bu/

a)

None

BD

Row

200 lb 9-23-30/a

Continuous corn Soybean/corn

Foliar fertilization of cropsFoliar fertilization of crops

Plants are not made to absorb Plants are not made to absorb nutrients through leavesnutrients through leaves

Nutrient use by crops is substantialNutrient use by crops is substantial

Leaf damage likely because of salt Leaf damage likely because of salt injuryinjury

Most research with soybean (podfill)Most research with soybean (podfill)

Micronutrients (B and Mn) for Micronutrients (B and Mn) for soybean under certain conditionssoybean under certain conditions

Response of soybean to foliar Response of soybean to foliar fertilization at three Minnesota fertilization at three Minnesota

locationslocations

WasecaWaseca BeckerBecker RosemouRosemountnt

TreatmentTreatment ------------- bu/a -------------------------- bu/a -------------

ControlControl 5454 5656 6161

Foliar Foliar (NPKS)(NPKS)

4x4x

5757 5353 6363

Adapted from Rehm, 1997

Summary of Midwest research for Summary of Midwest research for foliar B on soybeanfoliar B on soybean

ILIL MOMO OHOH WIWI

TreatmentTreatment ------------- bu/a -------------------------- bu/a -------------

ControlControl 42.242.2 43.043.0 52.452.4 51.251.2

FoliarFoliar 43.243.2 43.343.3 53.353.3 51.551.5

SoilSoil 38.338.3 42.842.8 52.552.5 51.951.9

Avg. of 0.25, 0.5, and 1.0 lb B/a foliar; 3 lb B/a soil

Response of soybean grown on a Response of soybean grown on a high pH, high O.M. soil to Mn high pH, high O.M. soil to Mn

fertilizationfertilizationTreatmentTreatment Mn RateMn Rate YieldYield

lb Mn/alb Mn/a bu/abu/a

ControlControl ---- 5050

RowRow 1010 6161

RowRow 2020 6464

RowRow 4040 6363

Foliar (2x)Foliar (2x) 0.50.5 6262

Foliar (2x)Foliar (2x) 1.01.0 6161

Foliar (2x)Foliar (2x) 2.02.0 5959Randall et al., 19752 yr. avg.

SummarySummaryConsider your motive and need for deep tillageConsider your motive and need for deep tillageSubsoiling more likely to be beneficial where Subsoiling more likely to be beneficial where compaction is identifiedcompaction is identifiedAvoid compaction Avoid compaction – Stay off wet soilsStay off wet soils– Watch load weightWatch load weight– Control trafficControl traffic

Tillage has a profound effect on soil properties Tillage has a profound effect on soil properties and affects nutrient availabilityand affects nutrient availability– Residue increases water content and lower Residue increases water content and lower

temperaturetemperature– Soil is more consolidatedSoil is more consolidated

SummarySummaryReduced tillage has numerous benefitsReduced tillage has numerous benefitspH, P, and K stratifypH, P, and K stratifyNo-till (strip-till) corn is more responsive to No-till (strip-till) corn is more responsive to fertilizationfertilizationBand placement often beneficial, however Band placement often beneficial, however broadcast may be acceptablebroadcast may be acceptableFoliar fertilization not recommended for Foliar fertilization not recommended for NPKSNPKSFoliar fertilization can be useful where a Foliar fertilization can be useful where a micronutrient need is identifiedmicronutrient need is identified