weed management in conservation agriculture in india makhan s. bhullar, madhulika pandey, sunny...
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Weed Management in Conservation Agriculture in India
Makhan S. Bhullar, Madhulika Pandey, Sunny Kumar and Gurjeet Gill1
Punjab Agricultural University, India; 1University of Adelaide, Australia
In this presentation
Description of cropping system, climate and soils in India History of development and adoption of CA in India Challenges associated with herbicide use in the IGP Management of emerging weed species in CA Opportunities for managing weeds in CA Socio economic influences on the adoption of CA Research, development, extension and training needs
for future sustainability of weed management in CA
MAJOR CROPPING SYSTEMS
Rice-rice (South and East India)
Rice-wheat (sub-tropical IGP)
Maize-wheat (tropical, sub-tropical, warm temperate)
Land use statistics in IndiaLand use Area
(M ha)% of total land use
Forest area 70.0 22.9Permanent pastures 10.3 3.4Net sown Area 140.8 46.0Total geographical area 328.7 -
Area sown more than once
54.4 -
Cropping intensity : 139% Irrigated area:: 35%
CROPPING SEASONS Summer (June-July to Sept-Oct)- Rice Winter (Oct-Nov to Feb-Mar)- Wheat, maize, potato,pulses Spring (Mar-Apr to May-June)- Maize, pulses, rice
Table: Areas under different crops in different seasons in IGP in India.
Summer season Winter season
Crop Area (%)
Crop Area (%)
Rice 65.5 Wheat 67.2
Maize 11.7 Mustard 1.3
Cotton 1.9 Pulse 4.1
Pearl millet 4.9 Potato 0.6
Sugarcane 5.9 Potato-wheat
1.8
Fallow 7.4 Fallow 15.4
Indo-Gangetic Plains in India IGP covers- Punjab, Haryana, UP Bihar, West BengalCLIMATE: Continental monsoon type, hot summer, cool- dry winter West: temperature extremes East: weather milderRAINFALL:
West -400- 600 mm East- high upto 1800mm85% rainfall (June-Sept)
SOILS : AlluvialCROPPING SYSTEMS
Rice-wheat Rice-fallow-fallow
Maize-wheat; Sugarcane, Cotton, Potato- Commercial crops
Challenges in Indian Agricultureo Stagnating net sown areao Reduction in per capita land availabilityo Climate change effects o Deterioration of land quality
Paradigm shift in farming practices needed - to ensure future productivity gains while sustaining natural resources
CA has potential to address problems of natural resource degradation & environmental pollution -while enhancing system productivity
Solutions?
History of Development and Adoption of CA in India
In India, ZT and CA adopted on >1.5 M ha Success in ZT wheat in irrigated RW system of IGP- worldwide, in rain-fed
agriculture
Rapid adoption in last 2 decades- Farm machinery & Herbicides
ZT wheat widely adopted in western IGP- started to increase in eastern IGP
Full benefits of ZT not realized- rice still grown by transplanting in puddled fields
DSR introduced (Punjab, Haryana) recently- findings of ACIAR project
In Punjab, DSR area increased (4 to 160 thousand ha from 2012 to 2015) -ready acceptance of CA technologies among farmers
FIRB, Laser levelling, UPMT being adopted in NW
CA offers avenues for diversification relay cropping of sugarcane, pulses, vegetables
Intercropping practiced in FIRB- wheat on beds and mint or sugarcane in furrows
In India, CA new concept
and its roots are only now beginning to find ground
Challenges associated with herbicide use in the IGP
Pesticides use in India estimated at 0.6 kg/ha- global average 3 kg
herbicides 25% of total pesticide market- rice, wheat, soybean
Shift to CA- increase herbicides during ‘transition period’?
-herbicide use increased in both CT and ZT- labour
Herbicides facilitate adoption of ZT- over reliance rapid resistance, public concerns
Herbicide resistance major problem in wheat could become problem in DSR
DSR increase reliance on herbicides- puddling, transplanting, flooding
ZT-DSR-more dependence on POST- reduced options (tillage, PPI, PE)
Post herbicides prone to resistance- ACCase and ALS inhibitors
New herbicides- tank-mixes to achieve effective weed control
Weed control in CA becomes easier over long-term-more uniform germination and greater seed predation, remain serious challenges in short-term after adoption
o Weed control in CA greater challenge than in conventional agriculture- behaviour of weeds, interaction with crops not fully understood
o In CA, surface residue influence soil temperature and moisture-which affect weed seed germination and emergence patterns.
o ZT- RICE: Shift towards aerobic grasses and sedges- adapted to establish at or close to soil surface
o ZT- WHEAT:: P. minor decreased, broadleaf increased- Rumex, Malva,
Convolvulus, Medicago, Polypogono Surface residues herbicides interaction- weed escapes-adjustment in
herbicide application timings or rates o Need alternative non-chemical methods- Challenging-tillage, herbicides
removed from system o Opportunity in CA- development of POST emergence broad-spectrum
herbicides
Management of emerging weed species in CA
Opportunities for managing weeds in CA
PREVENTIVE MEASURESHand-roguing weeds before seed-shed-important tactic in India
LASER LAND LEVELLINGUuniform crop establishment and growth -suppress weeds
STALE SEEDBED In CA, most weed seeds remain in topsoil
Reduces early competition, advantage over late-emerging weed seedlings.
Weedy rice in ZT-DSR
Treatments Total viable weed seed count (No./m2) at 0-5 cm soil depth at Ludhiana
At sowing At harvest
Without stale seedbed
675 1469
Stale seedbed with herbicide
246 1756
Stale seedbed with shallow tillage
255 1986
Effect of stale bed and herbicides on DSR grain yieldStale bed method
DSR grain yield (t/ha)
Unsprayed Pendimethalin Bispyribac Pendi fb bis
Without stale seedbed 0.691 3.092 1.805 6.431
Stale seedbed with herbicide
0.892 2.518 3.618 5.911
Stale seedbed with shallow tillage
2.094 3.881 3.266 7.384
LSDa at 5%- 0.393; LSDb -0.498
LSDa to compare difference between sub-plot means at same level of main-plot
LSDb to compare difference between main-plot means at same or different level of sub-plot
Laser levelling improves irrigation water management and results in uniform DSR establishment
Sowing time, tillage and residue management
WHEAT:
In NW IGP, early sowing give crop head start over P. minor
ZT+ Residue retention + Early sowing- suppress three flushes of P. minor and other weeds in wheat
Shredder-spreader can sow wheat in heavy residue mulch (8-10t/ha)
-such heavy mulch reduce establishment of weeds
SPRING CROPS
Earlier seeding improve competitive ability
Effect of residue mulch on emergence of major weeds of wheat 45 das (plants/2-m row length)
Residue mulch (t/ha)
P. minor C. album R. dentatus
0 185a 238a 42a
4 142ab 52b 9a
6 101bc 40bc 5b
8 60c 18bc 2b
10 80c 2c 0.3b
(Samar Singh, Karnal)
(ZT + R)-DSR and CT-DSR recorded similar yield under herbicides and IWM at Ludhiana
Succeeding wheat crop gave similar grain yield ZT-DSR can be rotated with ZT-TPR every few years to keep weed
pressure under check Planting wheat on FIRB system reduces weed pressure than
conventional flat seedbed
Weedmanagement
Tillage and residue managementCT-PTR
CT-wheat(ZT+R)-DSR
(ZT+R)- wheat
Herbicides 5.333 5.062
IWM 5.435 5.463
Unweeded 4.936 2.454
LSD (p=0.05)- 1.201
Effect of tillage, residue and weed management on grain yield (t/ha) in DSR in 2014 at Ludhiana
Cover cropping
Prior to termination- compete for resources
After termination- physical impedance, allelochemicals
Most rice weeds sensitive to mulching- effective strategy in ZT-DSR
Future adoption- identify herbicide strategies for high-residue systems
Interaction between cover cropp and weed control on DSR grain yield (t/ha) at Ludhiana
Treatment No cover crop
Cover crop
Weedy check 0.24 0.28
Weed free 4.91 5.24
Pendi fb Bis 4.10 3.33
LSD (p=0.05) 0.45
(Soil & Till Res.2015.147:39-49)
Before spray After spray
COMPETITIVE CROP CULTIVARS Important traits- early seedling vigor, more tillering, spreading nature Early maturing inbred and hybrids more effective e.g. PR 124
-Effective management of weedy rice Currently, cultivars bred for CT-PTR are used in ZT-DSR
WATER MANAGEMENT In WHEAT: high soil moisture favors Phalaris, Rumex and Polypogon-
-planting crop seed to moisture In ZT-DSR: Many weeds emerge before flooding is possible, making weed
management difficult
-rice seeds cannot germinate and survive under completely submerged conditions.
Development of rice cultivars capable of germinating under anaerobic conditions facilitate weed management via flooding in DSR
Enhance adoption of DSR -improved crop establishment if untimely rain comes soon after sowing
DEPLETING WEED SEED BANKS o Escaped weeds produce large number of
persistent seeds- remove before they set seed- affordable for most farmers in IGP
o Enhancing weed seed predation important in CA -newly produced weed seeds remain on soil surface
Post-dispersal predation reduced E. crus-galli seed input 2000 to 360 seeds/m2
ZT and surface residue enhance activity of weed seed decay agents- might contribute to reductions in weed seedbank in the long run
CROP ROTATIONS o Replacing wheat with egyptian clover, potato, oilseed rape for 2-3 years-
P. minoro Replacing rice with maize, cotton- P. minoro Fewer resistance cases in P. minor in diversified crop rotation fields o Avena ludoviciana in maize-wheat completely eliminated by growing rice
instead of maize o Intervention of short duration pulses, vegetables , oilseeds in RW system
o Diversified crop rotation improves management of problematic weeds- as selection pressure diversified by changing patterns of weed control tactics
Crop-rotations No. of P. minor seeds/kg top soil
0-7.5 cm 7.5 to 15.0 cm
Kapurthala Patiala Kapurthala Patiala
Rice-wheat 40 30 18 10
Rice-potato-wheat 7 0 3 0
Rice-Egyptian clover 0 0 0 0
Rice-oilseed rape 5 - 0 -
CHEMICAL WEED CONTROL Proper selection of herbicide formulations for CA- crop
residues may intercept 15-80% of applied herbicides
-Granular formulations may provide better control than liquid-formulations
Herbicide rotation important in avoiding or delaying evolution of resistance.
Several low-dose, high-potency, POST herbicides and mixtures available for major crops grown in CA.
Herbicide-tolerant crops useful tool-not available in India- shifts in weed flora or development of resistance in weeds?
INTEGRATED WEED MANAGEMENTAny single method used in isolation cannot
provide season-long effective weed control-variations in growth habit and life cycle of weeds
Weeds of secondary importance may emerge as primary weed problem- continuous use of single herbicide or herbicides with similar mode of action~ herbicide rotation/ mixtures
IWM approach- herbicide rotation, herbicide combinations, agronomic practices-to develop sustainable and effective weed management strategies under CA systems
Socio economic influences on the adoption of CA
CROP YIELD Success of ZT in NW India attributed to increase in wheat
yields following ZT in RW (5-7%) At long-term ACIAR project farmers field sites in Punjab, ZT-
wheat recorded 7% higher grain yield than CT wheat In eastern IGP, yield increase due to timely planting in ZT-
wheat vary from 400-1000 kg/ha
Table: Grain yield of wheat at ACIAR project long term farmers field sites in Punjab (2012-13)
No of farmers involved
Grain yield (t/ha) Yield gain
Zero tillage Farmers practice (CT)
10 5.82 5.42 7%
CA technologies tried in other cropping systems, but large knowledge gaps
Importance of skill development through experiential learning confirmed in recent farmer survey in Punjab
Presence of some yield penalty in first 1-2 years of DSR adoption- after that farmers achieved similar or higher yields than TPR
Research and farmer experience shows that productivity of wheat after DSR higher than TPR
In our recent survey, 70% farmers reported higher wheat grain yield after DSR (6.0 t/ha) than after TPR (5.54 t/ha)
Changes in yield gap between CT-PTR and DSR on farmer fields in Punjab over the years. (No. of farmers- 211)Starting year of DSR
Year Rice grain yield (t/ha)
Yield penalty for DSR (t/ha)DSR CT-TPR
20092009 7.51 8.11 0.60
2012 8.13 8.00 - 0.13
20102010 7.79 7.96 0.17
2012 8.25 8.10 - 0.15
20112011 6.74 7.89 1.15
2012 7.95 7.84 - 0.15
In all cases, the yield gap was reduced or eliminated completely by improvement in farmers skills over time
Economic analysis of DSR-wheat and TPR-wheat systems in Punjab, 2012-13.(No. of farmers- 211)
Descriptor Rice Wheat
DSR CT-TPR DSR-wheat
CT-PTR- wheat
Total expenditure (Rs/ha)
16124 22560 32787 32787
Grain yield (t/ha)
7.487 7.675 5.930 5.630
Gross returns (Rs/ha)
95834 98240 80055 76005
Net returns (Rs/ha)
79710 75680 47268 43218
Economic analysisFarmer experiences from
several locations in IGP showed that ZT-wheat in India generates substantial benefits through combined effects of yield improvement and cost-saving
According to our own survey of farmers in Punjab, the total returns from DSR-wheat system were USD 79-126/ha higher than in TPR-wheat system
Adoption of CA based technologies enhance soil quality, avoid crop residue burning, reduces environmental pollution
New drills able to cut through crop residue for ZT planting- non-burning of straw (~10t/ha) reducing release of 13-14 t CO2
ZT saves about 60 L of fuel/ha reducing emission of CO2 by 156 kg/ha/year
Adoption of CA in the long-term enhance C sequestration and build-up in soil OM and practical strategy to mitigate GHG emissions
Adoption of aerobic mulch management with reduced tillage to reduce methane emissions from the system
IMPACT ON THE ENVIRONMENT
Site-specific Adoption of CA Technologies
Researchable issues Understanding weed dynamics, their interference
potential- help making weed control timing decisions and maximum effectiveness Quantifying effects of crop residue mulches- how much residue
required for optimum weed suppression without affecting crop establishment
Quantifying effects of inclusion of cover crops on weed suppression- possible reductions in herbicide inputs for adequate weed control
Developing weed-competitive crop cultivars -rice cultivars with
anaerobic germination and iron efficient traits Estimating season-long seed predation- how it can be enhanced
Understanding interactions between crop residues and herbicides- degradation pathways, adsorption, transport processes
Herbicide mixtures- delaying resistance and improving control spectrum
POLICY ISSUES Legislation on prevention and monitoring of crop
residue burning- through incentives and penalties
Support development of CA machinery- and ensure its availability at affordable prices
CAPACITY BUILDING Capacity building of farmers to acquire, test and adopt
technologies through participatory approach- enable them to identify suitable CA practices for their farms
EXTENSION Organizing field days, field demonstrations, cross-farm
visits, mass media- promoting CA
Capacity building
DSR Farmer: Mr Gurpreet Singh
Gurpreet Singh standing in his vigorous crop of DSR in 2012
2008 2009 2010 2011 2012 20130
5
10
15
20
25 Area under DSR (ha)Area under PTR (ha)
Are
a u
nd
er
ric
e (
ha
)
DSR adoption trends at Gurpreet’s farm
Year
Thanks