by Alex Nuffer
Increasing temperatures will negatively impact global crop yield unless agricultural practices change. There is evidence that yields of staple crops, such as wheat, soybeans, maize, rice, and barley, are much lower then they have been due to climate change. Although changes in agricultural practices are necessary, there are economic and political constraints that play a major role in farmers’ management decisions. In order to overcome these constraints farmers seek for the most beneficial solution that will maximize their crop-specific profit margin with the least amount of risk. Lehmann et al. (2013) used models to formulate optimal management decisions in winterwheat and grain maize production under different climate scenarios in Switzerland from a risk-averse farmer’s perspective. The bioeconomic model generated agricultural optimal solutions for winterwheat and grain maize production depending on the different variables and climate scenarios. From these solutions the authors concluded that adaptation to climate change, if economic constraints are taken into account, might not be sufficient to counteract the negative impacts on the crop yield from climate change, therefore a closing of the income gap is necessary to support producers.
Niklaus Lehmann and colleagues used a bioeconomic model that links crop growth to an economic decision model to generate optimal management solutions for winter wheat and grain maize production. The model uses an algorithm that generates different sets of management decisions related to irrigation or nitrogen fertilization. CropSyst, which measures and simulates crop yield, takes weather and soil variables to generate mean crop yield. The economic model then takes the yield and computes the economic return of a specific set of management decisions.
Two sites in Switzerland, Payerne and Uster, were chosen to conduct the study. Payerne is prone to water scarcity and therefore needs irrigation, while Uster is located in a more humid area of Switzerland and does not need irrigation. Weather data, spanning 1981–2010, was gathered from the Swiss Meteorological Network and used to generate the climate scenarios for the model. The climate change scenarios were simulated by alterations in the monthly mean climate, which were derived from two climate models. The first model from the Swiss Federal Institute of Technology showed that in the year 2050, Payerne would experience a substantial decrease in precipitation during spring and summer. The second model from the Swedish Meteorological and Hydrological Institute showed that precipitation will increase in Uster, except in the month of June, and decrease in Payerne in spring in summer. Both scenarios indicated there would be a temperature increase.
The analysis showed that the management decisions depend on the climate scenarios and the site conditions. Irrigation is an optimal management decision for grain maize; however, profit is not equal in all regions. On the other hand, irrigation for winterwheat was found to be unnecessary because of the costs of irrigation systems and decrease in precipitation in the summer months. A decrease in fertilization intensity for both crops was proposed as an adaptation to climate change and an optimal management decision.
The results from the various scenarios on grain maize and winterwheat crop provide insight to the management problems that farmers could potentially face in the future due to climate change. The bioeconomic model will be a valuable resource in order to help farmers make management decisions that will maximize crop production and profit margin.
Niklaus Lehmann,Robert Finger,Tommy Klein,Pierluigi Calanca,Achim Walter. 2013. Adapting crop management practices to climate change: Modelling optimal solutions at the field scale. Agricultural Systems 117, 55–65 http://bit.ly/1k1fsco