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”. = =
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.
Location: KARAJ Alborz 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 عمق نمونه pH EC ds/m SAR % Na meq/lit Ca meq/lit N%N% P mg/kg K mg/kg O. M % Mg meq/lit Fe mg/kg Zn mg/kg Mn mg/k g 0-307.80.6722.214.171.1248.918126.96.36.199.28.5
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.
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.
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 Total dry matter (Kg/ha) Barley dry matter (Kg/ha) Chickpea dry matter (Kg/ha) Treatment 2981.06 ab 2916.16 ab 64.9 bc C 100 B 100 1757.4 c 1693.1 cd 64.26 bc C 100 B 75 1911.55 c 1828.61 cd 82.93 b C 100 B 50 220.1 d 0.0 c 220.1 a C 100 2151.12 bc 2137.33 bc 13.78 d C 75 B 100 2098.8 bc 2077.5 bc 21.36 cd C 75 B 75 1531.8 c 1451.83 d 79.95 b C 75 B 50 2567.7 ab 2554.7 ab 12.76 d C 50 B 100 2144.1 bc 2136.9 bc 7.183 d C 50 B 75 1726.6 c 1693.9 cd 33.23 cd C 50 B 50 3056.33 a 0.0 d B 100