Nitrogen Management for Nitrogen Management for Heavy Clay SoilsHeavy Clay Soils

David Dunn, Andrea Phillips, & David Dunn, Andrea Phillips, & Gene StevensGene Stevens

University of MissouriUniversity of Missouri

Delta CenterDelta Center

This Research Made Possible by a This Research Made Possible by a Grant from Cotton Inc. and the Grant from Cotton Inc. and the

Missouri State Support CommitteeMissouri State Support Committee

Columbia

Kansas City

Springfield

MU Delta CenterMU Delta Center

University of University of MissouriMissouriMain campusMain campus

Bootheel

PortagevillePortageville

St. Louis

Dr. Bobby PhippsDr. Bobby Phipps

Objective:Objective:

Develop a nitrogen managementDevelop a nitrogen management package for aggressively irrigated package for aggressively irrigated

cotton on heavy clay soils cotton on heavy clay soils in Missouri.in Missouri.

Methods and Materials:Methods and Materials:Site locationSite location

• Sharkey Clay soil Sharkey Clay soil – very fine, montmorillonite, thermic Vertic very fine, montmorillonite, thermic Vertic

HaplaqueptHaplaquept– pH: 7.1 P: 105 lb/a K 536 lb/a; pH: 7.1 P: 105 lb/a K 536 lb/a;

CEC: 28.6 meq/100grCEC: 28.6 meq/100gr– N recommendation: N recommendation:

• 800 lb lint = 110 lb N/a800 lb lint = 110 lb N/a• 1000 lb lint = 130 lb N/a1000 lb lint = 130 lb N/a

Methods and Materials:Methods and Materials:

• 5 N rates5 N rates– 0, 50, 100, 150, & 200 lbs/acre as NH0, 50, 100, 150, & 200 lbs/acre as NH44NONO33

• 3 application timings3 application timings– All pre-plant (PP)All pre-plant (PP)– 2 equal splits (pp + pin head square PHS)2 equal splits (pp + pin head square PHS)– 3 equal splits (PP + PHS + full bloom FB)3 equal splits (PP + PHS + full bloom FB)

ANOVA Table for yield ANOVA Table for yield

YearYear <.0001<.0001N rateN rate <.0001<.0001N*yearN*year 0.06530.0653SplitsSplits 0.01420.0142Splits*yearSplits*year 0.54230.5423N*splitsN*splits 0.72020.7202N*splits*yearN*splits*year 0.37340.3734

2-Year Average Lint Yields2-Year Average Lint Yields

N rateN rate SplitsSplits YieldYield00 ----- ----- 244 f244 f5050 1 1 469 e469 e100100 11 595 d595 d100100 2 2 604 d604 d100100 3 3 671 cd671 cd150150 1 1 692 cd692 cd150150 2 2 757 bc757 bc150150 3 3 753 bc753 bc200200 1 1 757 bc757 bc200200 2 2 837 ab837 ab200200 3 3 884 a884 a

2-Year Average yields for all 2-Year Average yields for all application timingsapplication timings

0

200

400

600

800

1000

1 2 3 4 5

Lin

t Y

ield

(lb

/a)

AA BB CC DD

EE

0 50 100 150 2000 50 100 150 200 N-Rate (lb N/a)N-Rate (lb N/a)

2-Year Average yields for 2-Year Average yields for 100, 150 & 200 lb N rates100, 150 & 200 lb N rates

600

700

800

900

1 2 3

# of Splits# of Splits

Lin

t Y

ield

(lb

N/a

)

AA

ABABBB

Fiber properties effects: 2005Fiber properties effects: 2005

PropertyProperty + N-rate+ N-rate + Splits+ SplitsTurn outTurn out ---- ----MicMic ++ --LengthLength ++++ ++++StrengthStrength ++ ++UniformityUniformity **** ****LeafLeaf ++ ++++ValueValue -- ****+ = general increase: ++ = consistent increase+ = general increase: ++ = consistent increase- = general decrease: -- = consistent decrease- = general decrease: -- = consistent decrease** = no consistent effect** = no consistent effect

Net Returns to Producers Net Returns to Producers Were Calculated By:Were Calculated By:• Commodity Credit Corporation Commodity Credit Corporation

Cotton loan rates for 2006 crop year Cotton loan rates for 2006 crop year $0.5235 / lb lint$0.5235 / lb lint

• Nitrogen priced @ $0.24/ lbs N + Nitrogen priced @ $0.24/ lbs N + application cost of $5.00/acreapplication cost of $5.00/acre

2-Year Average net returns2-Year Average net returns

N rateN rate SplitsSplits $/acre$/acre00 ----- ----- $127$1275050 1 1 $219$219100100 11 $230$230100100 2 2 $283$283100100 3 3 $312$312150150 1 1 $321$321150150 2 2 $350$350150150 3 3 $342$342200200 1 1 $343$343200200 2 2 $380$380200200 3 3 $400$400

2-Year Average value added by N 2-Year Average value added by N for all application timingsfor all application timings

0

50

100

150

200

250

300

1 2 3 4

Va

lue

ad

de

d b

y N

($

/a)

50 100 150 20050 100 150 200 N-Rate (lb N/a)N-Rate (lb N/a)

$98$98

$165$165

$211$211$225$225

2-Year Average value added by N 2-Year Average value added by N for 100, 150 & 200 lb N ratesfor 100, 150 & 200 lb N rates

# of splits# of splits

170

180

190

200

210

220

230

1 2 3

Va

lue

ad

de

d b

y N

($

/a)

$189$189

$211$211

$225$225

Conclusions:Conclusions:

• Current MU N recommendations for cotton grown on heavy clay soils may be too low.– N-rates above recommendations continued to

add value– 200 lbs N best rate

• Splitting N applications a profitable practice– 3 splits best strategy

• More study is needed

Questions?Questions?

Mark your Calendar Mark your Calendar for the for the

4646thth Delta Center Delta Center Field DayField Day

August 31, 2007August 31, 20079:00 AM9:00 AM

Portageville, MOPortageville, MO