TY  - JOUR
T1  - Modelling nitrogen leaching: Are we getting the right answer for the right reason?
JO  - Agricultural Water Management
VL  - 133
IS  - 
SP  - 74
EP  - 80
PY  - 2014/2//
T2  - 
AU  - van der Laan, M.
AU  - Annandale, J.G.
AU  - Bristow, K.L.
AU  - Stirzaker, R.J.
AU  - Preez, C.C. du
AU  - Thorburn, P.J.
SN  - 0378-3774
DO  - http://dx.doi.org/10.1016/j.agwat.2013.10.017
UR  - http://www.sciencedirect.com/science/article/pii/S0378377413003041
KW  - APSIM
KW  - DSSAT
KW  - Nitrate
KW  - SWB-Sci
AB  - 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 N O 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.
ER  -