Plant molybdenum uptake as mediated by synergism with phosphorus but antagonism with sulfur in a fertilized and mown meadow

Abstract Purpose Whether molybdenum (Mo) addition promotes Mo uptake by plants in nitrogen-fertilized ecosystems may depend on nutrient interactions. But this has rarely been paid attention to in continuously mown and nutrient-losing grassland ecosystems. Methods We investigated Mo uptake by three dominant species and how it varied with plant phosphorus and sulfur concentrations after 6-year combined nitrogen and Mo addition and mowing management in a cold meadow. Results Molybdenum addition increased Mo concentrations in the three plant species across all treatments due to increased soil available Mo. Without Mo addition, nitrogen addition significantly reduced Mo concentrations of Leymus chinensis irrespectively of mowing and of Stipa baicalensis with mowing. With Mo addition, the negative nitrogen-addition effect on plant Mo absorption was boosted for all plant species. This could be due to the fact that increases in plant sulfur absorption possibly induced antagonistic effects on plant Mo uptake. Additionally, reductions in plant phosphorus concentration weakened the synergistic uptake of Mo by plants with nitrogen addition, except for Carex duriuscula. Mowing only reduced Mo concentration of S. baicalensis without nitrogen addition under Mo addition. Conclusions Our results indicated that plant Mo deficiency could occur in nitrogen-fertilized ecosystems via nutrient interplay, facilitating it a necessity to supplement Mo.