Modifying the LEACHM model for process-based prediction of nitrate leaching from cropped Andosols
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Modifying the LEACHM model for process-based prediction of nitrate leaching from cropped Andosols Kei Asada & Sadao Eguchi & Rieko Urakawa & Sunao Itahashi & Tsuneo Matsumaru & Tomoko Nagasawa & Kazuhiro Aoki & Ken Nakamura & Hidetaka Katou
Received: 9 November 2012 / Accepted: 6 June 2013 # Springer Science+Business Media Dordrecht 2013
Abstract Aims Nitrogen (N) management strategies for reducing the risk of groundwater contamination around agricultural fields require precise prediction of N leaching using a process-based model. We modified LEACHM model for use in Andosols, which are characterized by slow soil organic carbon (SOC) mineralization and nitrate adsorption. Methods The modification was made with regard to the SOC mineralization of incoming plant-residue/manure and humus following the RothC model, as well as for nitrate adsorption. Empirical equations were employed to determine the parameters of the modified model. The ability of the modified LEACHM to predict N leaching was tested against existing data from a 4-year lysimeter
study for cropped Andosol and sandy soils and compared with that of the original model. Results The modified model improved the prediction of leached N concentrations and the loss of N from Andosol with relative improvements of 63.5 and 76.5 %, respectively, over the original model, while retaining model applicability in sandy soil. This effective modeling was achieved by using precise predictions of N mineralization in the humus pool along with SOC mineralization processes that were based on the RothC model. Conclusions The modification extended the applicability of LEACHM and may provide better N management strategies for reducing leaching from cultivated Andosols. Keywords Andosol . Groundwater quality . LEACHM . Modeling . Nitrate leaching . Soil organic carbon . RothC model
Responsible Editor: Klaus Butterbach-Bahl. K. Asada (*) : S. Eguchi : R. Urakawa : S. Itahashi : K. Aoki : K. Nakamura : H. Katou Carbon and Nutrient Cycles Division, National Institute for Agro-Environmental Sciences, Ibaraki 305-8604, Japan e-mail: [email protected] R. Urakawa Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan T. Matsumaru : T. Nagasawa Agro-Environment Sciences and Biotechnology Division, Chiba Prefectural Agriculture and Forestry Research Center, Chiba 266-0006, Japan
Introduction Agriculture is recognized as a contributor to nonpoint source pollution that leads to groundwater deterioration. Despite decades of vigorous efforts to reduce nitrogen (N) loss from farm lands, various studies have shown a gradual increase in the N concentrations of groundwater resources in Japan (MOE 2011) and globally (e.g., Grizzetti et al. 2011; Ju et al. 2006; Nolan et al. 2002). Excess N in farm land leads to widespread contamination of groundwater if it is lost from the crop root zone through leaching (Corwin and Vaughan 1997). Therefore, careful N management at
Plant Soil
the scale of the individual field should reduce groundwat
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