Road toward sustainable agricultural prodcution
11
THE ROAD TOWARD SUSTAINABLE PRODUCTION: The Evolution of Soil Structural Repair Under Zero Till, Controlled Traffic, Permanent Bed Farming *A.D. McHugh, # J. N. Tullberg and *D. M. Freebairn *Queensland Department of Natural Resources and Mines # Gatton College, University of Queensland Photo Source: “Storm over Bauhinia” Central Queensland Sustainable
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Transcript of Road toward sustainable agricultural prodcution
THE ROAD TOWARD SUSTAINABLE PRODUCTION:
The Evolution of Soil Structural Repair Under Zero Till, Controlled Traffic, Permanent Bed Farming
*A.D. McHugh, #J. N. Tullberg and *D. M. Freebairn
*Queensland Department of Natural Resources and Mines# Gatton College, University of Queensland
Photo Source: “Storm over Bauhinia” Central Queensland Sustainable Farming Systems Project
ObjectiveTo assess structural condition of a black cracking clay before and after wheel traffic was isolated to permanent tracks by measuring hydraulic conductivity, bulk density, plant available water capacity and cone penetrometer resistance.
Site 1895-1945: Dairy farm.
1945-1996: Conventional cereal & forage production.
1996-2003: Controlled Traffic – Permanent beds
N
1.00
1.10
1.20
1.30
1.40
1.50
1.60
0 7 12 22 0 7 12 22 0 7 12 22
T im e in crop (m on th s)
Bu
lk d
en
sity
(g
.cm
-3)
T rack
Adjace n t
B e d
100mm 200mm 300mm
Bulk Density
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0 7 12 22 0 7 12 22 0 7 12 22
T im e in crop (m on th s)
So
il m
ois
ture
co
nte
nt
(g.g
-1)
@ 3
0 k
Pa
T rack
Adjace n t
B e d
100mm 200mm 300mm
0.15
0.20
0.25
0.30
0.35
0.40
0 7 12 22 0 7 12 22 0 7 12 22
T im e in crop (m on th s)
So
il m
ois
ture
co
nte
nt
(g.g
-1)
@ 1
50
0 k
Pa
T rack
Adjace n t
B e d
100mm 200mm 300mm
DUL
DLL
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0 7 12 22 0 7 12 22 0 7 12 22
T im e in crop (m on th s)
Ava
ila
ble
so
il w
ate
r co
nte
nt
(cm
3.c
m-3
)
T rack
Adjace n t
B e d
100m m 200m m 300m m
`
AWC
0
10
20
30
40
50
Time since CTF implemented (months)
Cropping zoneTrack zoneWheeled cropping zone
7 12 22 58
PA
WC
(m
m)
in 0
.3m
Fallow
0
10
20
30
40
50
Time since CTF implemented (months)
PAW
C (m
m) i
n 0.
3m
Wheeled YearlyCropping zone
7 12 220
10
20
30
40
50
100 200 300Depth (mm)
PA
WC
(m
m)
Conventional farming (random traffic)
22 months CTF ( nil traffic)
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
0 7 12 22 0 7 12 22 0 7 12 22
T im e in crop (m on th s)
Km
atr
ix (
mm
.h-1
)
T rack
Adjace n t
B e d
100mm 200mm 300mm
Cropping zone Kmatrix
= 42.93+3.095 t -0 .073d
where t = t ime in crop (months)
d = depth (mm)
R2 = 0.76
SE = 14.6
n = 144
Unsaturated Hydraulic Conductivity
495
450
405
360
315
270
225
180
135
90
45
0
0 400 800 1200 1600 2000 2400 2800 3200
0
400
800
1200
1600
2000
1800mm
3000mm
Con
e In
dex
(kPa
)
Length of transect (mm)
Prob
e de
pth
(mm
)
495
450
405
360
315
270
225
180
135
90
45
0
0 400 800 1200 1600 2000 2400 2800 3200
0
400
800
1200
1600
2000
Con
e In
dex
(kPa)
Length of transect (mm)
Prob
e de
pth
(mm
)
Planting tynes - 728mm spacing
Conventional fallow (at time zero).
5 months after time
zero
Planted Dolichos lablab at time zero
500
460
420
380
340
300
260
220
180
140
100
60
20
0 600 1200 1800 2400 3000 3600
0
400
800
1200
1600
2000
Con
e In
dex
(kPa
)
Length of transect (mm)
Prob
e de
pth
(mm
)Planting tynes - 180mm spacing
500
460
420
380
340
300
260
220
180
140
100
60
20
0 400 800 1200 1600 2000 2400 2800 3200
0
400
800
1200
1600
2000
AdjacentBed
Con
e In
dex
(kPa
)
Length of transect (mm)
Prob
e de
pth
(mm
)
Adjacent
9 months ATZ
25 months ATZ
Planted Wheat 7 months ATZ
Planted Dolichos lablab 14 months ATZ
Depthmm
500
250
500mmTrack
Conclusions
Biological drilling and shrink/swell processes reduced cone penetration index from >2000kPa to 200-1000kPa to a depth of 400mm.
Conventional farming had left the soil profile degraded with plough layers, extreme densification and limited drainage.
Soil amelioration was evident after 3 cropping seasons of wheel traffic isolation, a direct result of pore size redistribution and increased connectivity – demonstrated by:
Bulk density decrease of 9% in the cropping zone from soil surface to 400mm.
A 38% increase in gravimetric moisture content range between DLL and DUL.
An increase in AWC of 5.2mm per 100mm of active root zone in top 400mm, and
Hydraulic conductivity increase of 65% (all layers 0-400mm).
