Ecologically-based weed management
through intercropping
Majid Aghaalikahni
Agronomy Department
Tarbiat Modares University
Outline for the main project:
I.
BARLEY / RAPESEED
II. BARLEY / GRASSPEA
III. BARLEY / CHICKPEA
IV. SWEET CORN / MUNGBEAN
Title of current presentation :
Barley/chickpea intercropping as an
environmentally- sound tool for weed management
in small scale dry land farms
I. Conventional management
Agricultural production systems in many parts of the world have shifted
from relatively small-scale polycultures to large-scale continuous
monocultures.
I. Conventional management
This shift in agriculture has been driven by advances in breeding and
chemical technologies that occurred after World War II.
I. Conventional management
These technologies have allowed growers to manage weeds and crop
fertility chemically rather than mechanically (i.e. not reliant on hand pulling
and hoeing)
I. Conventional management
Now, with the appropriate fertilizers and pesticides and equipment growers
can plant the same crop over a large area, year after year
But we have to know:
Herbicides are the main (sometimes only) method of weed management in
these systems. In this way, herbicide applications can be thought of as
“large hammers”.
=
=
Potential problems of the conventional management :
1. Cropping-systems have been greatly simplified (i.e. lower diversity).
2. Continuous cropping presents weeds with a “predictable” environment
weeds with biology similar to crop are particularly difficult to control
3. Large hammers evidently don’t work– we still have weed problems!
4. Large hammers select for resistance
5. As more weed species develop resistance, new herbicides must be
developed….weeds will eventually develop resistance to these too!
6. Synthetic pesticides and fertilizers can have unintended environmental
effects*
*This last point, in particular, has driven much of the current desire/pressure
to develop more ecologically-based weed and crop management strategies
Food web
What is the Main strategy in Ecologically-based
weed management ?
increasing cropping-system diversity
Why?......
Because greater cropping-system diversity may increase the
potential for ecological interactions to regulate pest populations,
potentially decreasing the need for intensive chemical
use.
How might one increase cropping-system
diversity?
COVER CROPS
CROP ROTATION
INTER-CROPPING
FIELD MARGINS/ HEDGE ROWS
WEEDY STRIPS
LAND-SCAPE LEVEL DIVERSITY
Research hypothesis:
•
A major concern for farmers growing grain legumes in low-input systems is
their weak competitive ability toward weeds.
•
Light, water and nutrient may be more completely absorbed and converted
to crop biomass by INTERCROPPING.
•
Barley and chickpea have different competitive ability for growth factors.
•
They not compete for the same ecological niches.
•
Interspecies competition is weaker than intraspecific competition for a given
factor.
•
Grain legumes / cereal INTERCROPPING may provide an ecological
method utilizing competition and natural regulation mechanisms reduce the
need for chemical fertilizer and to manage weeds with less use of
herbicides.
Methods and Materials
Location: KARAJ
Alborz Province(representing a semi-arid climate)
agricultural research station of Tehran University (Karaj campus)
Altitude: 1321 m
Latitude: 35 49َ N
Longitude: 51 50َ E
Precipitation: 243 mm
Soil texture : loam
Soil chemical properties
Mn
mg/k
g
Zn
mg/kg
Fe
mg/kg
Mg
meq/lit
O. M %
K
mg/kg
8.5
1.2
6.5
3.2
1.17
183
P
mg/kg
8.9
N
%
Ca
meq/lit
Na
meq/lit
SAR
%
EC
ds/m
pH
‫عمق نمونه‬
0.62
2.25
1.13
75
0.6
7.8
0-30
EXPERIMENTAL TREATMENTS
factorial of chickpea × Barley mixing ratio as follow
Barley
Chickpea
50, 75, and 100
percent of pure stand
50, 75, and 100
percent of pure stand
plus two control plots
(pure stand of chickpea and barley, 80 and 160 kg/ha respectively)
Treatments were arranged in a randomized complete blocks design
with 3 replications.
BARLEY
(Hordeum vulgare cv.Valfajr)
160 kg/ha
CHICKPEA (Cicer arietinum cv.4322)
80 kg/ha
Measured traits:
Weed biomass
Weed species frequency
Crops dry matter in pure stand and intercropped treatment
RESULTS and DISCUSSION
Weed diversity in our experiment
Commom name
Scientific name
Family
Fumitory
Fumaria asepala
Fumariaceae
Field bind weed
Convonvulus arvensis
Convolvulaceae
Common lamb. Squarters, Fathen
Chenopoduim album
Chenopodiaceae
Prostrate knot weed
Polygonum aviculare
Polygonaceae
Raphistre, Turnip weed
Rapistrum rugosum
Brassicaceae
Russian knap weed
Acroptilon repens
Asteraceae
Hypecum
Hypecum pendulum
Papaveraceae
Goldbachia
Goldbachia laevigata
Brassicaceae
Fumaria asepala
(Fumariaceae)
Convolvulus arvensis (Convolvulaceae)
Chenopodium album (Chenopodiaceae)
Polygonum avicular (Polygonaceae)
Rapistrum rugosum (Brassicaceae)
Acroptylon repens (Astearaceae)
Goldbachia laevigata (Brassicaceae)
RELATIVE FREQUENCY OF WEED
1. Chikpea monoculture has the highest weed density 
2.It was was dominantly consisted of fumitory 
3. Barley pure stand was kept weed free 
4. All additive intercropped treatment reduced weed frequency
significantly
5. All weed species were suppressed in intercrop treatments 
except fumitory which was alive up to flowering stage.

WEED BIOMASS
1.The highest amount of weed biomass (620 kg/ha) were
obtained in chickpea monoculture.
2. Green biomass of chickpea pure stand (220 Kg/ha)
suppressed by weed competition.

3. All experimental units including barley, significantly
reduced weed biomass.
4. It could be attributed to high growth rate and better
establishment of barley comparing to chickpea.
5. It could be concluded that barley has acceptable
competition ability against weeds.




100
b
b
b
b
b
barley(B) and chickpea© mixing ratio
b
B
10
0
b
C
75
B
10
0
C
75
B
75
C
75
B
50
C
50
B
10
0
C
50
B
75
C
50
B
50
50
C
10
0
C
10
0B
10
0
C
10
0B
75
C
10
0B
50
aboveground weeds
dry biomass (kg/ha)
650
a
600
550
500
450
400
350
300
250
200
150
b
b
0
b
Thank you
for your attention
Efharisto’ poli’
Damavand peak, 5619 masl
(Alborz chain of mountains)
Tehran- Iran
Mean comparison of forage dry biomass for
barley/chickpea intercropping
Treatment
Chickpea dry matter
(Kg/ha)
Barley dry matter
(Kg/ha)
Total dry matter
(Kg/ha)
C100B100
64.9bc
2916.16ab
2981.06ab
C100B75
64.26bc
1693.1cd
1757.4c
C100B50
82.93b
1828.61cd
1911.55c
C100
220.1a
0.0c
220.1d
C75B100
13.78d
2137.33bc
2151.12bc
C75B75
21.36cd
2077.5bc
2098.8bc
C75B50
79.95b
1451.83d
1531.8c
C50B100
12.76d
2554.7ab
2567.7ab
C50B75
7.183d
2136.9bc
2144.1bc
C50B50
33.23cd
1693.9cd
1726.6c
B100
0.0d
3056.33a
3056.33a