1. Weed Management in Conservation Agriculture in India Makhan S. Bhullar, Madhulika Pandey, Sunny Kumar and Gurjeet Gill 1 Punjab Agricultural University, India; 1 University of Adelaide, Australia

2. 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

3. 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 India Land use Area (M ha) % of total land use Forest area70.022.9 Permanent pastures10.33.4 Net sown Area140.846.0 Total 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

4. Table: Areas under different crops in different seasons in IGP in India. Summer seasonWinter season Crop Area (%) CropArea (%) Rice65.5Wheat67.2 Maize11.7Mustard1.3 Cotton1.9Pulse4.1 Pearl millet4.9Potato0.6 Sugarcane5.9 Potato- wheat 1.8 Fallow7.4Fallow15.4 Indo-Gangetic Plains in India IGP covers- Punjab, Haryana, UP Bihar, West Bengal CLIMATE: Continental monsoon type, hot summer, cool- dry winter West: temperature extremes East: weather milder RAINFALL: West -400- 600 mm East- high upto 1800mm 85% rainfall (June-Sept) SOILS : Alluvial CROPPING SYSTEMS Rice-wheat Rice-fallow-fallow Maize-wheat; Sugarcane, Cotton, Potato- Commercial crops

5. Challenges in Indian Agriculture o Stagnating net sown area o Reduction in per capita land availability o 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?

6. 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- F arm 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

7. 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

9. 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, Polypogon o 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

10. Opportunities for managing weeds in CA PREVENTIVE MEASURES Hand-roguing weeds before seed-shed- important tactic in India LASER LAND LEVELLING Uuniform 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./m 2 ) at 0-5 cm soil depth at Ludhiana At sowingAt harvest Without stale seedbed 6751469 Stale seedbed with herbicide 2461756 Stale seedbed with shallow tillage 2551986

11. Effect of stale bed and herbicides on DSR grain yield Stale bed method DSR grain yield (t/ha) UnsprayedPendimethalinBispyribacPendi fb bis Without stale seedbed0.6913.0921.8056.431 Stale seedbed with herbicide 0.8922.5183.6185.911 Stale seedbed with shallow tillage 2.0943.8813.2667.384 LSD a at 5%- 0.393; LSD b -0.498 LSD a to compare difference between sub-plot means at same level of main-plot LSD b to compare difference between main-plot means at same or different level of sub-plot

12. Laser levelling improves irrigation water management and results in uniform DSR establishment

13. 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. minorC. albumR. dentatus 0185a238a42a 4142ab52b9a 6101bc40bc5b 860c18bc2b 1080c2c0.3b (Samar Singh, Karnal)

14.  ( 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 Weed management Tillage and residue management CT-PTR CT-wheat (ZT+R)-DSR (ZT+R)- wheat Herbicides5.3335.062 IWM5.4355.463 Unweeded4.9362.454 LSD (p=0.05)- 1.201 Effect of tillage, residue and weed management on grain yield (t/ha) in DSR in 2014 at Ludhiana

15. 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 TreatmentNo cover crop Cover crop Weedy check0.240.28 Weed free4.915.24 Pendi fb Bis4.103.33 LSD (p=0.05) 0.45 (Soil & Till Res.2015.147:39-49)

16. Before spray After spray

17. 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

19. 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/m 2 ZT and surface residue enhance activity of weed seed decay agents- might contribute to reductions in weed seedbank in the long run

20. CROP ROTATIONS o Replacing wheat with egyptian clover, potato, oilseed rape for 2-3 years- P. minor o Replacing rice with maize, cotton- P. minor o 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 cm7.5 to 15.0 cm KapurthalaPatialaKapurthalaPatiala Rice-wheat 40301810 Rice-potato-wheat 7030 Rice-Egyptian clover 0000 Rice-oilseed rape 5-0-

21. 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?

22. INTEGRATED WEED MANAGEMENT Any 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

23. 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 tillageFarmers practice (CT) 105.825.427%

24. 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) DSRCT-TPR 2009 7.518.110.60 20128.138.00- 0.13 2010 7.797.960.17 20128.258.10- 0.15 2011 6.747.891.15 20127.957.84- 0.15 In all cases, the yield gap was reduced or eliminated completely by improvement in farmers skills over time

25. Economic analysis of DSR-wheat and TPR- wheat systems in Punjab, 2012-13.(No. of farmers- 211) DescriptorRiceWheat DSRCT-TPR DSR- wheat CT-PTR- wheat Total expenditure (Rs/ha) 161242256032787 Grain yield (t/ha) 7.4877.6755.9305.630 Gross returns (Rs/ha) 95834982408005576005 Net returns (Rs/ha) 79710756804726843218 Economic analysis  Farmer 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

26.  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 CO 2  ZT saves about 60 L of fuel/ha reducing emission of CO 2 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

27. Site-specific Adoption of CA Technologies

28. 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

29. 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

30. Capacity building

31. DSR Farmer: Mr Gurpreet Singh Gurpreet Singh standing in his vigorous crop of DSR in 2012 DSR adoption trends at Gurpreet’s farm Year