Walnuts are one of the most nutritionally dense foods on the planet, and could play a large role in achieving global food security. However, in non-organic walnut orchards, chemical fertilisers are typically applied to boost nut yields. When excessive amounts of these chemicals are applied, they can leach into the surrounding environment, damaging local ecosystems. To ensure that correct amounts of fertilisers are applied to walnut orchards, leaf samples are often analysed beforehand, but analysing enough leaf samples is time consuming and expensive. Now, Dr Ana Elisa Rato, Dr Adélia Sousa and their colleagues at MED Institute in the University of Évora have developed an inexpensive approach to assess nutrient levels in walnut orchards, by harnessing the power of satellite technology.