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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Soil Management and Sugarbeet Research » Research » Publications at this Location » Publication #342543
Research Project: Management Practices for Long Term Productivity of Great Plains Agriculture

Location: Soil Management and Sugarbeet Research

Title: Achieving lower nitrogen balance and higher nitrogen recovery efficiency reduces nitrous oxide emissions in North America’s maize cropping systems

Author
item OMONODE, REX - Purdue University
item HALVORSON, ARDELL - Retired ARS Employee
item GAGNON, BERNARD - Agriculture And Agri-Food Canada
item VYN, TONY - Purdue University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2017
Publication Date: 6/23/2017
Citation: Omonode, R.A., Halvorson, A.D., Gagnon, B., Vyn, T.J. 2017. Achieving lower nitrogen balance and higher nitrogen recovery efficiency reduces nitrous oxide emissions in North America’s maize cropping systems. Frontiers in Plant Science. doi: 10.3389/fpls.2017.01080.

Interpretive Summary: Few studies have assessed the hypothesis that an increase in plant nitrogen (N) uptake and/or N recovery efficiency (NRE) will reduce nitrous oxide (N2O) emission during crop production. In this investigation we examined the relationships between N2O emissions and crop N uptake and N use efficiency parameters that might be used to develop crop N management recommendations for both efficiency and environmental goals. Analyses were conducted to determine which commonly used crop N uptake parameters related most strongly to growing season N2O emissions under varying N management practices in North American maize systems. The relationship between N2O and N rate was sigmoidal with small emissions for N rates <130 kg ha-1, and a sharp increase for N rates from 130 to 220 kg ha-1; on average, N2O increased linearly by about 5 g N per kg of N applied for rates up to 220 kg ha-1. Negative relationships existed between N2O and NRE when management focused on N application rate. For every percentage point increase in NRE, N2O decreased by 13 g N ha-1 in response to N rates, and by 20 g N ha-1 for NRE changes in response to rate-by-timing treatments. Consistent positive relationships existed between N2O and Net Nitrogen Balance (NNB) and Surplus N (SN), regardless of rate and timing of N application. Neither N source nor placement influenced the relationship between N2O and NRE. Overall, our analysis indicated that an appropriate N rate applied at the right time can both increase NRE and reduce N2O emissions. However, N2O reduction benefits of optimum N rate-by-timing practices were achieved most consistently with management systems that reduced NNB through an increase of grain N removal or total plant N uptake.

Technical Abstract: Few studies have assessed the common, yet unproven, hypothesis that an increase of plant nitrogen (N) uptake and/or recovery efficiency (NRE) will reduce nitrous oxide (N2O) emission during crop production. Understanding the relationships between N2O emissions and crop N uptake and use efficiency parameters can help inform crop N management recommendations for both efficiency and environmental goals. Analyses were conducted to determine which of several commonly used crop N uptake-derived parameters related most strongly to growing season N2O emissions under varying N management practices in North American maize systems. Nitrogen uptake-derived variables included total aboveground N uptake (TNU), grain N uptake (GNU), N recovery efficiency (NRE), net N balance (NNB) in relation to GNU (NNB(GNU)) and TNU (NNB(TNU)), and surplus N (SN). The relationship between N2O and N application rate was sigmoidal with relatively small emissions for N rates <130 kg ha-1, and a sharp increase for N rates from 130 to 220 kg ha-1; on average, N2O increased linearly by about 5 g N per kg of N applied for rates up to 220 kg ha-1. Fairly strong and significant negative relationships existed between N2O and NRE when management focused on N application rate (r2 = 0.52) or rate and timing combinations (r2 = 0.65). For every percentage point increase, N2O decreased by 13 g N ha-1 in response to N rates, and by 20 g N ha-1 for NRE changes in response to rate-by-timing treatments. However, more consistent positive relationships (R2 = 0.73-0.77) existed between N2O and NNB(TNU), NNB(GNU) and SN, regardless of rate and timing of N application; on average N2O emission increased by about 5, 7, and 8 g N respectively, per kg increase of NNB(GNU), NNB(TNU), and SN. Neither N source nor placement influenced the relationship between N2O and NRE. Overall, our analysis indicated that a careful selection of appropriate N rate applied at the right time can both increase NRE and reduce N2O. However, N2O reduction benefits of optimum N rate-by-timing practices were achieved most consistently with management systems that reduced NNB through an increase of grain N removal or total plant N uptake.