Investigating water and nitrogen balances in the fruit orchard of Europe
Focusing on the highly productive Campo de Cartagena area in southeast Spain, a new interdisciplinary project seeks to enhance the understanding of how different crop rotation practices impact water and nitrogen balances under climate change scenarios.
In the Mediterranean climate, agriculture often involves intensively irrigated row crop (vegetable) rotations. The Campo de Cartagena in southeastern Spain, known as the vegetable and fruit orchard of Europe, exemplifies this practice. This region's high agricultural productivity, with three crop rotations per year, relies heavily on substantial irrigation water and fertilizer inputs.
In an effort to better protect the local environment, regional authorities recently implemented a regulation that permits only two crop rotations instead of the traditional three and further restricts fertilizer dosage. However, this regulation was enacted without assessing how management practices, such as the timing and choice of cover crops, affect overland flow, groundwater recharge, and nitrogen leaching into nearby aquifer.
A bottom-up approach
An ongoing project of the Improving Sustainability of Agricultural and Food Systems across Key Environmental Metrics Research Program aims to enhance the understanding of how fallow versus cover crops influence the water and nitrogen balance in the area, as well as the economic feasibility under current and future climatic conditions. By studying these various indicators, the researchers hope to provide recommendations for improving the sustainability of this prevalent type of agriculture in Mediterranean climates.
The researcher team from Eawag, ETH Zurich, and the Technical University of Valencia plan to achieve the project objectives in three steps, using a bottom-up approach that combines numerical modeling with field data and insights from local actors.
The first step is the quantification of the nitrous oxide emissions of fallow versus cover crops at the plot scale, using a biogeochemical model. Next, the researchers will estimate groundwater recharge, nitrogen leaching, and nitrogen in overland flow under fallow ver- sus cover crop use at the irrigation-district and regional scale using a hydrological model. In the later stage of the project, economic and environmental efficiency of cover crops will be assessed by performing a Data Envelopment Analysis.
“With our work, we assess the effectiveness of newly enacted crop rotation regulations in Campo de Cartegena. Our goal is to create knowledge that supports farmers and water authorities in making vegetable production more sustainable for the future.”Project Researcher Sandra Pool
Sharing the results
The combination of plot and regional scale modeling will provide crucial information into the environmental suitability of replacing a cash crop with a fallow period or a cover crop, and determine the optimal timing needed to achieve environmental benefits. Additionally, Data Envelopment Analysis will estimate how different cover crop practices affect the environmental and economic efficiency of agriculture in Campo de Cartagena.
The results will be shared with farmers, producer associations, and policymakers to support the implementation of more sustainable agricultural practices.
Find out more about the project:
Project Webpage Project Fact Sheet