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Ecologically-based weed management through intercropping
Majid Aghaalikahni
Agronomy Department
Tarbiat Modares University
I. BARLEY / RAPESEED
II. BARLEY / GRASSPEA
III. BARLEY / CHICKPEA
IV. SWEET CORN / MUNGBEAN
I. BARLEY / RAPESEED
II. BARLEY / GRASSPEA
III. BARLEY / CHICKPEA
IV. SWEET CORN / MUNGBEAN
Outline for the main project:
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”.
=
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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 CROPSCOVER CROPS
CROP ROTATIONCROP ROTATION
INTER-CROPPINGINTER-CROPPING
FIELD MARGINS/ HEDGE ROWSFIELD MARGINS/ HEDGE ROWS
WEEDY STRIPSWEEDY STRIPS
LAND-SCAPE LEVEL DIVERSITYLAND-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.
Location: KARAJAlborz Province(representing a semi-arid climate)
Altitude: 1321 m
Latitude: 35 49 َ N
Longitude: 51 50 َ E
Precipitation: 243 mm
Soil texture : loam
agricultural research station of Tehran University (Karaj campus)
Soil chemical properties
Mnmg/kg
Znmg/kg
Femg/kg
Mgmeq/lit
O. M% K
mg/kg Pmg/kg
N%
Cameq/lit
Nameq/lit
SAR%
ECds/m
pHعمق نمونه
8.5 1.2 6.5 3.2 1.17 183 8.9 0.62 2.25 1.13 75 0.6 7.8 0-30
EXPERIMENTAL TREATMENTS factorial of chickpea × Barley mixing ratio as follow
ChickpeaBarley
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 .
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
RELATIVE FREQUENCY OF WEED
1 .Chikpea monoculture has the highest weed density2.It was was dominantly consisted of fumitory
3 .Barley pure stand was kept weed free4 .All additive intercropped treatment reduced weed frequency
significantly5 .All weed species were suppressed in intercrop treatments
except fumitory which was alive up to flowering stage .
WEED BIOMASS1.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.
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a
0
50
100
150
200
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barley(B) and chickpea© mixing ratio
ab
oveg
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weed
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dry
bio
mass (
kg
/ha)
Damavand peak, 5619 masl (Alborz chain of mountains)
Tehran- Iran
Thank you for your attention
Efharisto’ poli’
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