Global Change Impacts on Rice- Wheat Provision and the Environmental Consequences Peter Grace SKM - Australia Cooperative Research Centre for Greenhouse Accounting

Rice-Wheat Production Systems

Trends in Rice Yields

Trends in Wheat Yields

Reasons for Productivity Decline Intensification-inefficient N use Soil organic matter decline Inappropriate water management Soil structural decline Micro-nutrient deficiencies Pest and disease build-up Narrow genetic base

Reasons for Productivity Decline Intensification-inefficient N use Soil organic matter decline Inappropriate water management Soil structural decline Micro-nutrient deficiencies Pest and disease build-up Narrow genetic base

Reasons for Productivity Decline Intensification-inefficient N use Soil organic matter decline Soil structural decline Inappropriate water management

Nitrogen Distribution in Rice-Wheat Inputs Outputs

Environmental Impacts Intensification-inefficient N use Leaching of nitrates to groundwater Greenhouse gas production - N 2 O

Environmental Impacts Soil organic matter decline Greenhouse gas production - CO 2 + CH 4

Environmental Impacts Inappropriate water management –Irrigation without adequate drainage –Groundwater rises Salinity (salt) and sodicity (Na)

Environmental Impacts Salinity (salt) and plants –Root water uptake reduced –Tolerance varies Sodicity –Decreased microbial activity –Soils less permeable Waterlogging Run-off Erosion Lower plant available water contents

Environmental Impacts Inappropriate water management –Excessive irrigation Groundwater depletion Increased pumping - GHG production - CO 2

Groundwater Depletion

South Asia - Water Use

Environmental Impacts Soil structural decline Waterlogging - GHG production - N 2 O + CH 4

CLIMATE CHANGE REDUCED GHGs NEW PRODUCTION SYSTEMS CURRENT PRODUCTION SYSTEMS IMPROVED FOOD PRODUCTION ADAPT to climate variability MITIGATE further climate change IMPACT of climate variability on current production systems GHGs

Key Conclusions from IPCC TAR WG I An increase in extreme weather event Higher maximum temperatures & hot days Higher minimum temperatures More intense precipitation events Increased summer drying and risk of drought Increased Asian summer monsoon precipitation variability

Climate Extremes

South Asia Climate - GCM Outputs

Asia - Simulated Rice Yields - ORYZA1

Wheat Losses of 1-1.5% yield/day occur with late planting after end November Delay due to inability to sow –Late harvest of previous crop –Seedbed preparation

Adaptation to Climate Change Depends on region specific climate changes Promote flexibility - traditional ecological knowledge Avoid stress at critical growth stages –Adjustment of planting dates –Change cultivar

Mitigation of Climate Change Amount of residue retained No and reduced tillage Reduction in fallow periods Flood reduction

CLIMATE CHANGE REDUCED GHGs NEW PRODUCTION SYSTEMS CURRENT PRODUCTION SYSTEMS IMPROVED FOOD PRODUCTION ADAPT to climate variability MITIGATE further climate change IMPACT of climate variability on current production systems GHGs

Global Warming Potential of Rice-Wheat Production Systems Standard nomenclature CH 4 = 20 x CO 2 N 2 O = 310 x CO 2 CARBON EQUIVALENTS CARBON to PRODUCTIVITY RATIO

Rice-Wheat system - long-term trials (20 yr)

Rice-Wheat system - long-term trials (20 yr) - remove and/or burn crop residues

Rice-Wheat system - long-term trials (20 yr)

Enhancing Rice-Wheat Provision -Conclusions Improved agronomic management New germplasm Biodiversity