Modelling nitrogen leaching : are we getting the right answer for the right reason?

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Authors

Van der Laan, Michael
Annandale, John George
Stirzaker, Richard John
Du Preez, C.C.
Thorburn, P.J.

Journal Title

Journal ISSN

Volume Title

Publisher

Elsevier

Abstract

The complexities and challenges in quantifying N leaching have led to development of a range of measurement and modelling techniques, but none are widely applied. Observations that N moves more slowly than water through the soil profile has resulted in different approaches being used to simulate impeded N movement in crop models: (i) by accounting for nitrate NO−3 adsorption to the soil, (ii) by considering incomplete mixing between resident and draining soil water fractions or (iii) a combination of both.We compare and discuss strengths and weaknesses of these approaches. Our inability to directly measure model parameters (especially with regards to simulating N dynamics), and the risk of compensating errors during model testing and calibration, often results in low confidence in simulated N leaching. We caution that our current ability to simulate N leaching is in most cases not yet well enough developed for reliable and accurate predictions. We recommend a more strategic approach involving better linking measurement and modelling to improve understanding of the critical soil processes that control N leaching as one way of further improving our understanding and quantification of N leaching.

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Keywords

APSIM, DSSAT, Nitrate, SWB-Sci

Sustainable Development Goals

Citation

Van der Laan, M, Annandale, JG, Bristow, KL, Stirzaker, RJ, Du Preez, CC & Thorburn, PJ 2014, 'Modelling nitrogen leaching : are we getting the right answer for the right reason', Agricultural Water Management, vol. 133, pp. 74-80.