Optimizing rice yields while minimizing yield‐scaled global warming potential. (24th February 2014)

• Record Type: Journal Article
• Authors: Pittelkow, Cameron M.; Adviento‐Borbe, Maria A.; van, Chris; Hill, James E.; Linquist, Bruce A.
• Is Part Of: Global change biology. Volume 20:Number 5(2014:May)
• Page Start: 1382
• Page End: 1393
• Publication Date: 2014-02-24
• Subjects: Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.12413
• Languages: English
• ISSNs: 1354-1013

Abstract

<abstract abstract-type="main" id="gcb12413-abs-0001"> <title>Abstract</title> <p>To meet growing global food demand with limited land and reduced environmental impact, agricultural greenhouse gas (GHG) emissions are increasingly evaluated with respect to crop productivity, i.e., on a yield‐scaled as opposed to area basis. Here, we compiled available field data on CH<sub>4</sub> and N<sub>2</sub>O emissions from rice production systems to test the hypothesis that in response to fertilizer nitrogen (N) addition, yield‐scaled global warming potential (GWP) will be minimized at N rates that maximize yields. Within each study, yield N surplus was calculated to estimate deficit or excess N application rates with respect to the optimal N rate (defined as the N rate at which maximum yield was achieved). Relationships between yield N surplus and GHG emissions were assessed using linear and nonlinear mixed‐effects models. Results indicate that yields increased in response to increasing N surplus when moving from deficit to optimal N rates. At N rates contributing to a yield N surplus, N<sub>2</sub>O and yield‐scaled N<sub>2</sub>O emissions increased exponentially. In contrast, CH<sub>4</sub> emissions were not impacted by N inputs. Accordingly, yield‐scaled CH<sub>4</sub> emissions decreased with N addition. Overall, yield‐scaled GWP was minimized at optimal N rates, decreasing by 21% compared to treatments without N addition. These results are unique compared to aerobic cropping systems in which N<sub>2</sub>O emissions are the primary contributor to GWP, meaning yield‐scaled GWP may not necessarily decrease for aerobic crops when yields are optimized by N fertilizer addition. Balancing gains in agricultural productivity with climate change concerns, this work supports the concept that high rice yields can be achieved with minimal yield‐scaled GWP through optimal N application rates. Moreover, additional improvements in N use efficiency may further reduce yield‐scaled GWP, thereby strengthening the economic and environmental sustainability of rice systems.</p> </abstract>