A review of quantitative tools for assessing the diffuse pollution response to farmer adaptations and mitigation methods under climate change

In an era of global climate change, the agricultural sector faces the challenge of increasing the production of safe and nutritious food supplies to meet a growing world population while safeguarding the environment. Farmers will adapt their agricultural practices to a changing climate to safeguard against loss of production and to take advantage of any positive climatic conditions. Certain management practices have been found to reduce the effects of agricultural practices on the environment and a key question is how efficient these are under the current climate, and will these management practices still be relevant under a changing climate? Mathematical modeling is the only tool available to assess the potential efficacy of proposed agricultural management practices to help evaluate their impacts on the environment in a future climate. This chapter attempts to evaluate a range of published models for their capability to simulate agricultural production systems and associated environmental system losses under a changing climate, and their ability to introduce farmer adaptation and mitigation methods. The chapter focuses on the applicability of the models given a set of essential criteria related to scale, biophysical processes, and land management. Thirty models are initially examined, based on details found in published papers, against specific criteria, viz: (1) spatial scale and temporal scale, ease of use, and ability to consider a change in climate; (2) ability to simulate nutrient cycling processes, specifically carbon and nitrogen dynamics with microbial turnover, mineralization-immobilization, nitrification and denitrification, plant nutrient uptake, and phosphorus cycling; (3) ability to consider a water balance and water movement through soil; and (4) ability to introduce and modify agricultural practices relating to crop and livestock management. The chapter does not compare any actual model simulations. It was concluded that albeit no single model incorporates all above stated requirements, there were three models, DAYCENT, PASIM, and SPACSYS which will accommodate most features. These models may therefore be considered in the context of this chapter to be the most suitable for a general assessment of the effects of farm mitigation and adaptation on environmental losses under a changing climate. © 2011 Elsevier Inc.