Soil footprint: A simple indicator to communicate and quantify soil security

Soil erosion is a major threat to soil security, and therefore to agriculture. To address this challenge, effective strategies are needed to protect soil resources without compromising crop yields. Currently, there are three main players involved: scientists, policymakers, and land managers. However, the technical knowledge required to understand how soil erosion affects food production hinders the communication of the potential benefits of soil sustainability strategies to nontechnical stakeholders, such as farmers and food producers. Moreover, a major player in this fight is still missing, consumers. If there is no connection between soil and society then the soil itself may not be valued and it is less likely to be managed sustainably. In this study, we propose the concept of soil footprint, defined as the ratio of soil loss to crop yield, to communicate, quantify, and compare soil security for different crops. It is a versatile concept that can be applied for a multitude of potential practical uses. To showcase some of these potential uses, we used national data to calculate the soil footprint of the ten main crops in Spain. We demonstrate the utility of this metric to compare and rank crops, identify problematic regions, and assess the effect of land management on the soil footprint. The soil footprint indicator offers advantages in terms of simplicity, facilitating easy calculation, comparison, and interpretation by non-technical users. This can engage society in soil conservation, empower land managers to define sustainable soil management strategies, and promote policies to enhance soil security.