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

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DSR adoption trends at Gurpreet’s farm

Year

Thanks