Phosphorus absorption capacity of Lotus corniculatus and Festuca arundinacea during sward establishment

Abstract

Lotus corniculatus and Festuca arundinacea are currently sown in phosphorus deficient soils of the mesothermal humid Pampas, in Argentina. We hypothesised that the legume seedlings might withstand competition from grass through greater phosphorus root absorption capacity which would result in higher nutrient acquisition, and compared phosphorus absorption capacity and total phosphorus acquisition of both species at increasing levels of P supply during seedling establishment. Plants grown in a greenhouse were harvested 40 days after sowing. Biomass productivity and phosphorus content of shoots and roots were used to calculate phosphorus absorption capacity per unit of root biomass and phosphorus acquisition per plant. Birdsfoot trefoil showed higher root phosphorus absorption capacity at P supply up to 25 ppm in soil (P < 0.05), which resulted in nutrient acquisition similar to tall fescue although trefoil showed lower root biomass over all levels of P supply (P < 0.05). The higher phosphorus absorption capacity plus higher root tissue phosphorus concentration of trefoil (P supply up to 100 ppm, P < 0.05) may assist legume establishment in mixed swards with tall fescue.