Climate change impacts on irrigated maize in Mediterranean climates: Evaluation of double cropping as an emerging adaptation alternative

Because its relevance for the sustenance and livelihood of human systems, the assessment of the impacts that future climatic conditions may have on agricultural productivity becomes a key piece of information for agricultural scientists and policy makers. Several authors have performed assessments of the impacts of climate change on agricultural productivity evaluating alternatives for adaptation that are closely related to current management practices and do not cover a wider range of options. The objective of this paper is to document the main impacts of climate change scenarios on maize productivity in central Chile, an irrigated Mediterranean region, and evaluate the possibility of double cropping as a response to changes in the length of the growing season. The results of this research have lead to the conclusion that maize can be affected by climate change, with yield reductions between 10% and 30%, depending on climate change scenario and the type of hybrid used. In addition, climate change will also affect other relevant variables such as the rate of development, allowing the crop to complete its growing cycle in shorter periods of time. In future climate scenarios it is also possible to see a reduction of total irrigation needs, because actual evapotranspiration is diminished. In extreme climate change scenarios, double cropping is a more effective alternative of adaptation compared to management practices such as the use of early sowing dates and reductions in nitrogen fertilization. Double cropping also results in an increase on water demands, nitrogen use, and will likely have an impact on weed, pest and diseases. If climate change also results into impacts on river flows, the incorporation of double cropping could be constrained by imbalances between water demand and supply.