Linking supplementary data to soil P levels and stratification

Linking supplementary data to soil P levels and stratification

GLPF Grant- Team meeting #5July 23-24, 2013

Hypotheses

• We would find increased P stratification with: Recent manure application No soil inversion Broadcast fertilizer application

• We would find increased P stratification with poorly drained soils belonging to hydrologic soil groups C/D (not examining today)

Statistical analysis

• Used analysis of variance (ANOVA) followed by a Tukey test when possible Differences in means

• Used Kruskal Wallis (KW) followed by a Dunn’s test when unequal variances or non-normal data Differences in ranks

• Each figure depicts the mean or average value ± 95% confidence intervals 95% certain the mean is in this range

Inve

rsio

n

Red

uced

Mul

ch

No-

till

Tota

l 0-8

" M3P

(ppm

)

0

10

20

30

40

50

60

Influence of tillage used for corn

Total

Corn tillage Soybean tillage

Inversion, <5% coverReduced, <30% coverMulch, >30% coverNo-till or strip till

Wheat tillage

Inve

rsio

n

Red

uced

Mul

ch

No-

till

Rat

io o

f top

: to

tal

0.0

0.5

1.0

1.5

2.0

aab b b

Influence of tillage used for corn

• Reduced tillage had lower mean total 0-8”soil P (39ppm) compared to mulch tillage (44ppm; ANOVA, P=0.019)

• Inversion tillage had a lower mean stratification, both in terms of the ratio (1.36 vs. 1.53; KW, P=0.03) and difference (11ppm vs. 18ppm; KW, P=0.001)

Total Ratio Difference

Inve

rsio

n

Red

uced

Mul

ch

No-

till

Tota

l 0-8

" M3P

(ppm

)

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60

aba

b ab

Inve

rsio

n

Red

uced

Mul

ch

No-

tillD

iffer

ence

[Top

- To

tal]

M3P

(ppm

)

0

5

10

15

20

25

a

abb b

Corn tillage Soybean tillage

Inversion, <5% coverReduced, <30% coverMulch, >30% coverNo-till or strip till

Wheat tillage

Combined tillage practices

Combined Tillage Practices

Inversion with any cropReduced till for almost all cropsReduced till corn + Mulch tillReduced till corn + no-tillMulch till corn + mulch or no-tillNo till corn + mulch or no-till


Inve

rsio

n

Red

uced

Red

/Mul

ch

Red

/No-

till

Mul

ch/N

o-til

l

Con

t. N

o-til

l

Tota

l 0-8

" M3P

(ppm

)

0

10

20

30

40

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60

ab b bab

a

b

Inve

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n

Red

uced

Red

/Mul

ch

Red

/No-

till

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ch/N

o-til

l

Con

t. N

o-til

l

Rat

io o

f top

: to

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0.0

0.5

1.0

1.5

2.0

Inve

rsio

n

Red

uced

Red

/Mul

ch

Red

/No-

till

Mul

ch/N

o-til

l

Con

t. N

o-til

lDiff

eren

ce [T

op -

Tota

l] M

3P (p

pm)

0

5

10

15

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25

Combined tillage practices

• Lower soil P levels in reduced till corn followed by mulch till (35ppm) compared to other tillage practices (42ppm; ANOVA P<0.001)

• Yet, no significant differences in stratification across tillage practices (ratio: KW, P=0.16; difference: KW, P=0.08)


Combined Tillage Practices


Fertilizer application method

• Lumped all broadcast and all banding, regardless of season• Banding lead to higher soil P levels (mean= 37ppm vs. 41ppm; MW, P=0.024)• However, broadcast had higher levels of stratification (ratio: 1.56 vs. 1.48,

MW, P=0.001; difference: 17ppm vs. 15ppm, MW, P=0.015)

Total Ratio DifferenceB

road

cast

Ban

ded

Tota

l 0-8

" M3P

(ppm

)

0

10

20

30

40

50

60

*

Bro

adca

st

Ban

ded

Rat

io o

f top

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0.0

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*

Bro

adca

st

Ban

ded

Diff

eren

ce [T

op -

Tota

l] M

3P (p

pm)

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25

*

Fertilizer application- How

Broadcast and unincorporatedBroadcast and incorporated within 1 weekBroadcast and incorporated after 1 weekBanded with a corn planterBanded more than 2" with injection

P Fertilizer Application

Broadcast Banded with a corn planter

Non

e

His

toric

Infre

quen

t

Freq

uent

Rat

io o

f top

: to

tal

0.0

0.5

1.0

1.5

2.0

a b aab

Non

e

His

toric

Infre

quen

t

Freq

uent

Diff

eren

ce [T

op -

Tota

l] M

3P (p

pm)

0

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35

ab a

c bc

Non

e

His

toric

Infre

quen

t

Freq

uent

Tota

l 0-8

" M3P

(ppm

)

0

10

20

30

40

50

60

70

a

b b

c

Manure application history

• Frequent manure application lead to higher mean soil P (58ppm), and any history of application had higher levels (47ppm) compared to no known applications (38ppm; KW P<0.001)

• Although the ratio had significant differences, the pattern is difficult to interpret (KW P=0.001)

• The difference between top and total was higher for recent application of manure (25ppm vs 16ppm, KW P=0.02)


Manure Application

No known applicationsApplied historically Recent but infrequent applicationRecent and frequent application

Combined manure, tillage, fertilizer application

Manure applied recentlyInversion with any cropReduced till for almost all cropsReduced till corn + Mulch tillReduced till corn + no-tillMulch till corn + mulch or no-tillNo till corn + mulch or no-till

BroadcastBanded


• Manure application tended to result in higher mean soil P (51ppm vs. 39ppm)

• Banding had higher soil P in reduced till corn/no-till (45ppm) compared to broadcast (36ppm) Trend in others

BroadcastBanded

Tota

l 0-8

" M3P

(ppm

)

0

20

40

60

Man

ure

Inve

rsio

n

Red

uced

Red

/Mul

ch

Red

/No-

till

Mul

ch/N

o-til

l

Con

t. N

o-til

l

aab

cbc bc

abc

c

abc

cbc

ANOVA P<0.001


• Ratio was lowest under inversion tillage and reduced till corn/no-till with banding (1.4) compared to reduced till with broadcast (1.6; KW P=0.007)

• Difference was highest with manure application (25ppm) and lowest with inversion (12ppm; KW P=0.006)

Diff

eren

ce [T

op -

Tota

l] M

3P (p

pm)

0

5

10

15

20

25

30

35

Man

ure

Inve

rsio

n

Red

uced

Red

/Mul

ch

Red

/No-

till

Mul

ch/N

o-til

l

Con

t. N

o-til

l

a

b

Rat

io o

f top

: to

tal

0.0

0.5

1.0

1.5

2.0

a ab

Man

ure

Inve

rsio

n

Red

uced

Red

/Mul

ch

Red

/No-

till

Mul

ch/N

o-til

l

Con

t. N

o-til

l

BroadcastBanded

Classification and Regression Tree (CART) analysis

• Next step in analyzing these data• Hypothetical example:

We tended to find higher soil test P with recent manure application and banded fertilizer application

Recent manure

application?

STP = 51 ppmn=120

Banded fertilizer

application?

STP = 41 ppmn=382

Other potential factors? Soil type,

tillage, slope?

yes no

yes no

yes no

Classification and Regression Tree (CART) analysis

We tended to find lower stratification with inversion tillage, higher stratification with recent manure application and broadcast fertilizer

Recent manure

application?

Ratio = 1.60Diff = 27ppm

n=120

Broadcast fertilizer

application?


n=206

Other potential factors? Soil type,

tillage, slope?

yes no

yes no

yes no

Inversion tillage?


n=61

yes no

Questions?

Linking supplementary data to soil P levels and stratification

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