Phosphorus (P) is a limiting nutrient in many agroecosystems and, apart from affecting plant growth, can also limit biological N 2 fixation (BNF) by leguminous plants. Thus, increasing P supply can have a positive effect on BNF particularly in P-deficient soils. Here, we provide new insights into the response of hairy vetch ( Vicia villosa ), widely adopted as a legume cover crop, to P limitations, by comparing the effects of...