Linking supplementary data to soil P levels and stratification
description
Transcript of 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
)
0
10
20
30
40
50
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
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
50
60
ab b bab
a
b
Inve
rsio
n
Red
uced
Red
/Mul
ch
Red
/No-
till
Mul
ch/N
o-til
l
Con
t. N
o-til
l
Rat
io o
f top
: to
tal
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
20
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)
Total Ratio Difference
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
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
: to
tal
0.0
0.5
1.0
1.5
2.0
*
Bro
adca
st
Ban
ded
Diff
eren
ce [T
op -
Tota
l] M
3P (p
pm)
0
5
10
15
20
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
5
10
15
20
25
30
35
ab a
c bc
Non
e
His
toric
Infre
quen
t
Freq
uent
Tota
l 0-8
" M3P
(ppm
)
0
10
20
30
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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)
Total Ratio Difference
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
Combined manure, tillage, fertilizer application
• 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
Combined manure, tillage, fertilizer application
• 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?
Ratio = 1.55Diff = 16ppm
n=206
Other potential factors? Soil type,
tillage, slope?
yes no
yes no
yes no
Inversion tillage?
Ratio = 1.35Diff = 11ppm
n=61
yes no
Questions?