Agricultural Water Management 163 (2016) 305–318 Contents lists available at ScienceDirect Agricultural Water Management journal homepage: www.elsevier.com/locate/agwat Assessing the effectiveness of split fertilization and cover crop cultivation in order to conserve soil and water resources and improve crop productivity Ganga Ram Maharjan a,∗ , Marianne Ruidisch b , Christopher L. Shope c , Kwanghun Choi d , Bernd Huwe a , Seong Joon Kim e , John Tenhunen b , Sebastian Arnhold a,f a University of Bayreuth, Department of Soil Physics, Universitaetsstrasse 30, 95440 Bayreuth, Germany b University of Bayreuth, Department of Plant Ecology, Universitaetsstrasse 30, 95440 Bayreuth, Germany c US Geological Survey, 2329 Orton Circle, Salt Lake City, UT, USA d University of Bayreuth, Department of Biogeographical Modelling, Universitaetsstrasse 30, 95440 Bayreuth, Germany e Konkuk University, Department of Civil & Environmental System Engineering, Seoul 143-701, Republic of Korea f University of Bayreuth, Professorship of Ecological Services, Nuernberger Strasse 38, 95447 Bayreuth, Germany a r t i c l e i n f o Article history: Received 19 April 2015 Received in revised form 1 October 2015 Accepted 4 October 2015 Keywords: BMP Cover crop Crop yield Intensive agriculture Monsoon Nitrate loss Sediment loss Split fertilization a b s t r a c t Intensive agricultural practices implemented to secure increased crop yields have potentially negative environmental effects due to the generation of sediment and nutrients from agricultural fields. The mon- soon climate and current agricultural practices on mountainous landscapes of the Haean catchment in South Korea have significantly affected water quality by transporting sediment and nutrients to down- stream water bodies. The aim of this study is to suggest strategies for a permanent reduction of sediment and nitrate from this catchment through an efficient application of best management practices (BMPs). We applied three BMPs; split fertilizer application (SF), winter cover crop cultivation (CC), and a combina- tion of the two (SFCC) to major dryland crops (cabbage, potato, radish and soybean) in order to investigate their effectiveness at the catchment scale through the Soil and Water Assessment Tool (SWAT) model. We found that the SF scenario reduced nitrate pollution while sediment and crop yield did not change relative to the baseline (BL) scenario. The application of the CC scenario reduces both sediment and nitrate load while crop yields increased. The combination of split fertilization and cover cropping (SFCC) showed the highest positive effect on reducing sediment and nitrate and increasing crop yields compared to a single application. We estimated the variability in the effectiveness of BMPs for major crop types and could demonstrate that specific sites and crop types, such as soybean, were less influential in reducing sediment and nitrate loads. Those sites and crops could be considered for additional BMP measures to mitigate water deterioration by target pollutants. Recommendations for BMP applications should also consider minor crops and other land use types in order to reduce overall water pollution and efficiently improve crop yields in this catchment. © 2015 Elsevier B.V. All rights reserved. 1. Introduction In recent decades, agricultural production has been intensified to meet the food demand of a growing population. Worldwide, the intensification of agricultural production is consistent with nega- tive environmental impacts, including deterioration of water and soil resources (Lal, 2008; Matson et al., 1997; Tilman et al., 2002). Agricultural mismanagement such as over-fertilization, inappro- ∗ Corresponding author. Fax: +49 921552246. E-mail addresses: mhjgangaram@gmail.com, Ganga-Ram.Maharjan@uni-bayreuth.de (G.R. Maharjan). priate pesticide application, over-tillage as well as over-grazing trigger nutrient leaching and soil erosion which can turn agri- cultural ecosystems into non-productive areas (Scherr and Yadav, 1996). Land degradation and soil losses are threats not only to eco- nomic and social welfare by decreasing yields and farmers income, but also ecosystem services such as soil protection, water and nutrient regulation, and water provision (water availability and quality). From a regional perspective, absolute agricultural land degradation was found to be highest in Asia, accounting for 206 million hectares (Oldeman, 1994; Scherr and Yadav, 1996). Mean- while, the world wide degradation of productive farmland was recognized and a trend reversal by achieving global zero net land degradation by 2030 was postulated by the UN Convention to Com- http://dx.doi.org/10.1016/j.agwat.2015.10.005 0378-3774/© 2015 Elsevier B.V. All rights reserved.