For decades, scientists concerned about plastic pollution focused on the oceans, where floating debris is easy to see. More recently, attention has turned to a less visible problem: microplastics in agricultural soil. These particles, usually defined as fragments smaller than five millimetres, reach farmland through several routes. Sewage sludge, which is widely spread on fields as a cheap fertiliser, contains large quantities of fibres shed from synthetic clothing. Plastic films used to cover crops break down in the sun and are rarely collected in full. Even irrigation water and wind can carry particles from nearby roads and towns. Once in the soil, microplastics may persist for many decades. Laboratory studies suggest that they can alter the structure of the soil, reduce the activity of earthworms and other organisms, and in some cases carry chemical additives that are taken up by plants. However, researchers caution that most of these experiments use concentrations far higher than those found in typical fields, and that methods for measuring microplastics in soil are not yet standardised. As a result, it is still unclear how serious the threat is to crop yields or to human health. What is clear is that the amount entering soil is growing, and that removing it afterwards is practically impossible. For this reason, many scientists argue that the most effective response is to limit the sources, for example by treating sludge more thoroughly and by developing crop films that can be fully recovered or that genuinely biodegrade.