Abstract
Meeting the future food security challenge without further sacrificing environmental integrity requires transformative changes in managing the key biophysical determinants of increasing agronomic productivity and reducing the environmental footprint. Here, we focus on Chinese rice production and quantitatively address this concern by conducting 403 on-farm trials across diverse rice farming systems. Inherent soil productivity, management practices and rice farming type resulted in confounded and interactive effects on yield, yield gaps and greenhouse gas (GHG) emissions (N2O, CH4 and CO2-equivalent) with both trade-offs and compensating effects. Advances in nitrogen, water and crop management (Best Management Practices—BMPs) helped closing existing yield gaps and resulted in a substantial reduction in CO2-equivalent emission of rice farming despite a tradeoff of increase N2O emission. However, inherent soil properties limited rice yields to a larger extent than previously known. Cultivating inherently better soil also led to lower GHG intensity (GHG emissions per unit yield). Neither adopting BMPs only nor improving soils with low or moderate productivity alone can adequately address the challenge of substantially increasing rice production while reducing the environmental footprint. A combination of both represents the most efficient strategy to harness the combined-benefits of enhanced production and mitigating climate change. Extrapolating from our farm data, this strategy could increase rice production in China by 18%, which would meet the demand for direct human consumption of rice by 2030. It would also reduce fertilizer nitrogen consumption by 22% and decrease CO2-equivalent emissions during the rice growing period by 7% compared with current farming practice continues. Benefits vary by rice-based cropping systems. Single rice systems have the largest food provision benefits due to its wider yield gap and total cultivated area, whereas double-rice system (especially late rice) contributes primarily to reducing GHG emissions. The study therefore provides farm-based evidence for feasible, practical approaches towards achieving realistic food security and environmental quality targets at a national scale.
Highlights
Global aggregate food production needs to increase by at least 60–70% by 2050 to meet the projected food demands from population growth and economic development [1]
No specific permissions were required for doing these on-farm trials in each location, because all locations are located in major Chinese rice production domains
The rice yields in 403 on-farm trials conducted on soils with different inherent productivities across the major rice farming systems were on average 5998 kg ha-1 for early rice, 6370 kg ha-1 for late rice, and 8305 kg ha-1 for single rice across all sites and management practices (FPs and best management practice (BMP))
Summary
Global aggregate food production needs to increase by at least 60–70% by 2050 to meet the projected food demands from population growth and economic development [1]. Actual crop production targets vary widely by countries, but it is generally acknowledged that the increase in production must largely come from higher yields on currently cultivated land to avoid further environmental degradation, destruction of natural ecosystems and loss of biodiversity [1,2]. Rice (Oryza sativa L.) is the most important food crop in the developing world and is the staple food of more than half of the global population, many of whom are extremely vulnerable to high rice prices [3].
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