Campus Units

Agronomy

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

1-2018

Journal or Book Title

Global Change Biology

Volume

24

Issue

1

First Page

e303

Last Page

e317

DOI

10.1111/gcb.13866

Abstract

The frequency and intensity of extreme weather years, characterized by abnormal precipitation and temperature, are increasing. In isolation, these years have disproportionately large effects on environmental N losses. However, multi-year sequences of extreme weather years (e.g., wet-dry vs. dry-wet) and annual crop rotation (legume-cereal vs. cereal-legume) may interact to affect cumulative N losses across the complete crop rotation sequence. We calibrated and validated the DAYCENT model with a comprehensive set of biogeophysical measurements from a maizesoybean rotation managed at three different N fertilizer inputs with and without a winter cereal rye cover crop in Iowa, USA. Our objectives were to determine: i) how two-year sequences of extreme weather years interact with annual crop rotation sequence to affect two-year cumulative N losses, and ii) if the inclusion of a winter cover crop between corn and soybean and N fertilizer management mitigate the effect of extreme weather on N losses. Using historical weather data (1951-2013), we created nine two-year weather scenarios with all possible combinations of the hottest and driest (‘dry’), coolest and wettest (‘wet’), and average (‘normal’) weather years. We analyzed the effects of these scenarios following a period of relatively normal weather. Compared to the normal-normal two-year weather scenario, two-year extreme weather scenarios affected two-year cumulative NO3- leaching (range: -28 to +295%) more than N2O emissions (range: -54 to +21%). Moreover, the two-year weather scenarios had non-additive effects on N losses: although dry weather decreased NO3- leaching in isolation, two-year cumulative NO3- losses from the dry-wet scenario were 89% greater than the normal-normal scenario. Cover crops reduced the effect of extreme weather on NO3- leaching, but not N2O emissions. As the frequency of extreme weather events is expected to increase, understanding of interactions between crop rotation and interannual weather patterns can be used to mitigate the effect of extreme weather on environmental N losses.

Comments

This is a manuscript of an article published as Iqbal, Javed, Magdalena Necpalova, Sotirios V. Archontoulis, Robert P. Anex, Marie Bourguignon, Daryl Herzmann, David C. Mitchell, John E. Sawyer, Qing Zhu, and Michael J. Castellano. "Extreme weather‐year sequences have nonadditive effects on environmental nitrogen losses." Global change biology 24, no. 1 (2018): e303-e317. doi: 10.1111/gcb.13866.

Copyright Owner

John Wiley & Sons Ltd

Language

en

File Format

application/pdf

Available for download on Tuesday, January 01, 2019

Published Version

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