Nitrogen addition enhances terrestrial phosphorous retention in grassland mesocosms

Nitrogen (N) and phosphorus (P) are fundamental for plant biomass production in grasslands, often co-limiting, have become major freshwater pollutants. By factorially applying gradients of N P to field-based grassland mesocosms, we tested saturating thresholds uptake as nutrients increase whether simultaneous potentially additive growing-season demand reduces flows dissolved subsurface leachate. We quantified the seasonality nutrient losses, differences by functional group (grasses, forbs), impacts increasing on root:shoot ratios, contrasted vegetated unvegetated treatments isolate edaphic influences. Overall, most added were retained plants soil–80% 99% P. Co-limitation dynamics powerful but asymmetrical with additions reducing leachate, having little influence N. retention was primarily influenced season—most lost prior peak when presumably lower. Nutrients reduced ratios foliage no detectable effect retention, possible because root remained unchanged. Similarly, there impact loss. Despite substantial uptake, leachate concentrations still exceeded regional levels safe drinking water prevention algal blooms. This work reveals how co-limitation can accelerate capture indicating that significantly reduce nutrients. However, offseason failure meet water-quality standards despite high reveal vegetative-based solutions grasslands important likely insufficient without complimentary measures inputs.