Tradeoffs in land and water productivity of rice with establishment method and irrigation schedule Sudhir Yadav and Liz Humphreys

Outline Establishment method of rice Performance of DSR and AWD  field experiment  Model simulation Conclusion Research need

Rice agriculture is the engine of growth for rural and urban economies…and maintaining peace

Conventional practice of growing Rice Nursery raising Puddling Transplanting

Issues and Concerns Labour cost and availability Ground water depletion/deterioration Energy requirement to pump groundwater Productivity of rice Soil and environmental health *Some of these problems can be handled by changing establishment method of rice

Other practices of establishing Rice Establishment method of rice Transplanting Puddled Manual Mechanical Unpuddled After dry Tillage After Zero Tillage Direct seeding Wet seeding Puddled field Broadcasting Line sowing Unpuddled field Broadcasting Line sowing Dry seeding After dry tillage After Zero tillage (+M/-M)

Direct seeding

Mechanical transplanting, WSR & DSR labour saving- reduced costs - timely establishment DSR beneficial to non-rice crops in the rotation (e.g. wheat & maize) due to avoidance of puddling = improved soil) opportunity to introduce conservation agriculture in rice – upland rotations e.g. rice-wheat (zero tillage, surface residue retention = mulch) Drivers of different establishment method

Performance of DSR in IGP DSR is considered as a “water saving technology” but the fact is- it is just an “establishment method”

Increasing “drying period" IRRIGATION + RAIN Adapted from Bouman & Tuong 2001 Rice is very sensitive to water deficit

11 Ladha et al. (2000) Irrigated rice & wheat Rainfed rice, partially irrigated wheat Punjab: “Food basket of India”

Regardless of establishment method, rice very sensitive to soil drying With more water stress (>20 kPa), yield penalty was higher in DSR than PTR. Water requirement of DSR vs puddled transplanted rice (PTR) Punjab, India (clay loam, deep watertable) 4 irrigation treatments - daily or soil water tension 20, 40 or 70 kPa at cm

for potential, water-limited, and/or nitrogen-limited conditions (lowland, aerobic rice) Effects of weather, irrigation, nitrogen fertilizer, general management, variety characteristics, soil type (hydrological, native N supply) version 2.0, 2004; and 2.13, 2009 Fully documented User-friendly interface (FSEWin) Tutorial available Standard evaluation methodology Standard data sets available Oryza2000: a rice growth simulation model

Application of ORYZA Calibration: from 2 year field experiment data Evaluation: 4 irrigation regime each year Simulation: 40 years ( ) past weather data of Ludhiana, India Irrigation threshold First 30 DAS: 2-d after disappearance of water After 30 DAS: SWT based (10,20, kPa)

Performance of ORYZA2000 to predict grain yield PTR DSR

Performance of ORYZA2000 to predict water balance components

Simulation with 40 years past weather data

Grain yield and IW input with different irrigation schedule

Where is the water saving? (Percolation+Seepage) Can we count it under “water saving”

Safe AWD- PTR vs DSR Stage 1 Stage 2 Stage 3 y = 4.14x R² = 0.97 y = 3.24x R² = 0.98

Cracking in soil

SWT and Cracking intensity* *measurement with WinDIAS Sofware

Water productivity: PTR vs DSR

TargetTechnologyPredicted outcome Yield (t ha -1 ) WP I (g kg -1 ) WP ET (g kg -1 ) ET mm Maximizing yieldDSR-CF Maximizing WP I DSR-30 kPa Maximizing WP ET PTR-20 kPa Minimizing ETPTR-60 kPa Selection of establishment method and irrigation schedule

25 The biggest gains in irrigation water saving are from adoption of safe AWD (establishment method is of secondary importance) Safe AWD reduced runoff, percolation & seepage (no effect on ET) (i.e. it will not make more water available for other uses where runoff & deep drainage can be used elsewhere) reduced irrigation requirement for DSR by ~30% compared with PTR in Punjab, India (needs to be evaluated in other situations) requires ability to deliver water when needed (because of sensitivity of rice to soil drying) Significance of above for irrigation system managers

irrigation scheduling for DSR o can we reduce frequency of irrigation during some crop stages & further reduce irrigation input without reducing yield? o how is this affected by soil type, climate, varietal duration etc? o develop farmer friendly techniques for AWD Field water tube (shallow water table) Tensiometer (deep water table) does adoption of zero tillage & mulching in a rice- upland cropping system increase total system yield, WPi & WP of depleted water? what are the real water savings at higher spatial scales (irrigation schemes, catchments, river basins)? Research needs for AWD & DSR

Acknowledgement Gurjeet Gill, The University of Adelaide, Australia Liz Humphreys, International Rice Research Institute, Philippines Tao Li, International Rice Research Institute, Philippines S.S.Kukal, Punjab Agricultural University, India

Thank You !