effect of mulch on water use and productivity if wheat in punjab, india: field and simulation...
DESCRIPTION
Presentation from the WCCA 2011 event held in Brisbane, Australia.TRANSCRIPT
Balwinder Singh, IRRI, PhilippinesLiz Humphreys, IRRI, PhilippinesDon Gaydon, CSIRO, AustraliaPhil Eberbach, CSU, Australia
Effect of mulch on water use and productivity of wheat in Punjab, India-Field and simulation studies
1
Methodology • Field experiments (2006-07 and 2007-08)
• Crop model application
2
Ludhiana, Punjab
Treatments
Mulch treatments • With mulch (8 t/ha)• Without mulch
3
Irrigation management
-First irrigation at -40kPa SMP at 15-20 cm soil depth
- Subsequent irrigations at -40kPa SMP at 35-40 cm soil depth
4
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 1061131201271341411481550
10
20
30
40
50
60
70
80
Days after sowing
Rain
/irr
igati
on (m
m)
Rainfall/irrigation- 2006-07
Rain- 160 mm
Mulch irrigation = 75 mm
Non-mulch irrigation= 150 mm
1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 134 141 148 1550
10
20
30
40
50
60
70
80
Days after sowing
Rain
/irr
igati
on (m
m)
5
Rainfall/irrigation- 2007-08
Rain- 88 mm
Non-mulch irrigation= 225 mm
Mulch irrigation = 150 mm7 days28 days
Grain yield (kg/ha)
Total biomass production (t/ha)
6
2006-07 2007-080
1
2
3
4
5Mulch Non mulch
Gra
in y
ield
(k
g/h
a)
2006-07 2007-080
2
4
6
8
10
12
Mulch Non mulch
Bio
ma
ss
pro
du
cti
on
(t/
ha
)
NS
Evapotranspiration (ET)
7
.
ET= R+I-D-R-Δ(θv)
R = Rainfall
I = irrigation (volume was measured with a Woltman helical turbine meter)
D= drainage below root zone (1.8 m) (zero) ( based soil matric potential gradients to 180
cm depth)
R= runoff, zero as the plots had small bunds
Δ(θv) = change in soil water content (0-180 cm) between sowing and harvesting
Water balance equation
Evapotranspiration (ET)
8
.
2006-07 2007-080
50
100
150
200
250
300
350
400
450
Mulch Non mulch
ET
(m
m)
N/SN/S
Grain water productivity based on ET (kg/ha.mm)
Biomass water productivity based on ET (kg/ha.mm)
9
WPET = grain yield or biomass/ET
Units, kg/ha.mm
Water productivity
2006-07 2007-080
2
4
6
8
10
12
14Mulch Non mulch
Gra
in W
PE
T (
kg
/ha
/mm
)
2006-07 2007-080
5
10
15
20
25
30
35
40
Mulch Non mulch
Bio
ma
ss
WP
ET
(k
g/h
a/m
m)
APSIM application
10
APSIM validation
Balwinder-Singh, Gaydon DS, Humphreys E, Eberbach PL (2011). Evaluating the performance of APSIM for irrigated wheat in Punjab, India. Field Crops Research, 124, 1-13.
Model attribute R2 (co-efficient of determination)
Grain yield 0.89
Biomass 0.95
ET 0.86
• Weather data at Ludhiana, Punjab (1970-2006) (36 years)
• Soil type-Sandy loam (290 mm PAWC, 0-180 cm)
Variables• ±mulch ( 0, 8 t/ha)
• 8 irrigation schedules
(10%, 20%, 30%, 40%, 50%, 60% and 70%SWD of 0-60 cm soil layer, rainfed)
11
Simulation set up
12
• Wheat var. PBW 343 sown 10 November
• 150 plants/m2
• Initial soil water content at field capacity
0 1 2 3 4 5 6 7 8 90
0.2
0.4
0.6
0.8
1
1.2
10%-NM
10%-M
40%-NM
40%-M
70%-NM
70%-M
0-NM
0-M
Grain yield (t ha-1)
Cu
mu
lati
ve
Pro
ba
bili
ty
Grain yield - mulch and irrigation interactions
13
Yield ranged from 3 to 8 t/ha
~ 0.5 t/ha
In 60% years yield < 7 t/ha
Biomass production
14
4000 6000 8000 10000 12000 14000 16000 18000 200000
0.2
0.4
0.6
0.8
1
1.2
40%-NM
40%-M
0-NM
0-M
Biomass production (kg/ha)
Cum
ulati
ve p
roba
bilit
y
0 100 200 300 400 500 6000
0.2
0.4
0.6
0.8
1
1.2
10%-NM
10%-M
40%-NM
40%-M
70%-NM
70%-M
Irrigation water (mm)
Cu
mu
lati
ve p
rob
abili
ty
Irrigation water input
15
At 40% SWD, mulch reduced irrigations by 1 in ~50% years
Average reduction ~40 mm
0 20 40 60 80 100 120 140 160 180 2000
0.2
0.4
0.6
0.8
1
1.2
10%-NM
10%-M
40%-NM
40%-M
0-NM
0-NM
Soil Evaporation (mm)
Cu
mu
lati
ve p
rob
abili
ty
Soil evaporation
16
Es reduced
by ~ 40mmIn irrigated wheat
by ~20 mm in rainfed wheat
50 100 150 200 250 300 350 400 4500
0.2
0.4
0.6
0.8
1
1.2
10%-NM
10%-M
40%-NM
40%-M
70%-NM
70%-M
0-NM
0-M
Transpiration (mm)
Cu
mu
lati
ve p
rob
abili
ty
Transpiration
17
Followed the same trends as by grain yield
No effect in frequent irrigation treatments
0 100 200 300 400 500 6000
0.2
0.4
0.6
0.8
1
1.2
10%-NM
10%-M
40%-NM
40%-M
70%-NM
70%-M
0-NM
0-NM
ET (mm)
Cu
mu
lati
ve p
rob
abili
ty
Evapotranspiration
18
ET reduced by mulch ~ 40mm (same as Es) in frequent irrigation treatments
However, No difference for ET was observed in field study
No difference in rainfed treatment
19
5 7 9 11 13 15 17 19 210
0.2
0.4
0.6
0.8
1
1.2
10-NM
10-M
40-NM
40-M
70-NM
70-M
Grain WPET (kg ha-1 mm-1)
Cu
mu
lati
ve
pro
ba
bili
ty)
Grain water productivity (WPET)
Highest WP at 40% SWD
Conclusions• Mulch reduced irrigation requirement when irrigated
according to soil water status (by 1 irrigation in ~50% of years)
• Mulch reduced Es of well-irrigated wheat by ~40 mm• No effect of mulch on grain yield of irrigated wheat• APSIM Wheat predicted ET lowered by mulch
BUT field study showed no effect of mulch on ET (due to increased T) – a worry!
Which is right? - needs further investigation.
20