Soil carbon management in large-scale Earth system modelling: implications for crop yields and nitrogen leaching

S Olin,M Mishurov,T A M Pugh,G Schurgers,S Zaehle,B Smith,D Wårlind,M Lindeskog,A Arneth,B D Stocker

doi:10.5194/esd-6-745-2015

Abstract

Abstract. Croplands are vital ecosystems for human well-being and provide important ecosystem services such as crop yields, retention of nitrogen and carbon storage. On large (regional to global)-scale levels, assessment of how these different services will vary in space and time, especially in response to cropland management, are scarce. We explore cropland management alternatives and the effect these can have on future C and N pools and fluxes using the land-use-enabled dynamic vegetation model LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator). Simulated crop production, cropland carbon storage, carbon sequestration and nitrogen leaching from croplands are evaluated and discussed. Compared to the version of LPJ-GUESS that does not include land-use dynamics, estimates of soil carbon stocks and nitrogen leaching from terrestrial to aquatic ecosystems were improved. Our model experiments allow us to investigate trade-offs between these ecosystem services that can be provided from agricultural fields. These trade-offs are evaluated for current land use and climate and further explored for future conditions within the two future climate change scenarios, RCP (Representative Concentration Pathway) 2.6 and 8.5. Our results show that the potential for carbon sequestration due to typical cropland management practices such as no-till management and cover crops proposed in previous studies is not realised, globally or over larger climatic regions. Our results highlight important considerations to be made when modelling C–N interactions in agricultural ecosystems under future environmental change and the effects these have on terrestrial biogeochemical cycles.

Highlights

Growing population along with rapidly changing dietary preferences pose one of the key economical and environmental challenges of this century (Gerland et al, 2014; Hertel, 2015)
We explore cropland management alternatives and the effect these can have on future C and N pools and fluxes using the land-use-enabled dynamic vegetation model LPJ-GUESS (Lund–Potsdam–Jena General Ecosystem Simulator)
Our results show that the potential for carbon sequestration due to typical cropland management practices such as no-till management and cover crops proposed in previous studies is not realised, globally or over larger climatic regions

Summary

Introduction

Growing population along with rapidly changing dietary preferences pose one of the key economical and environmental challenges of this century (Gerland et al, 2014; Hertel, 2015). Since the beginning of the 20th century there has been an increase in crop yields and overall production, especially since the 1950s (Steffen et al, 2015), as a result of agricultural intensification driven by substantial advances in agricultural practices and technology, improved crop varieties and an increased application of N and P fertiliser (Evans, 1999; Spano et al, 2003). Yield increases on existing land may be achieved through further development of high-yielding varieties or through further improvements in the efficiency of agricultural practices, the latter especially in regions where gaps between actual and potential yields are large (Licker et al, 2010; Mueller et al, 2014). The enhanced input of nitrogen (N) into ecosystems, jointly with other technical developments, has played a major role in the large increase in agricultural productivity over the last 50 years, often termed the “green revolution”

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