Nitrogen fertilization of grass leys: Yield production and risk of N leaching

Evidently, adjusting fertilization to attain the economic optimum according to the developed models may reduce N fertilization, particularly when N0-yield is high, and thus lower the N balances for perennial grass leys. However, concerns about the risk of N leaching losses when using only inorganic N fertilization seems less crucial due to its low level and weak association with N balances. Even vigorous drops in N input and N balance would result only in minor reduction of N leaching loss, by a maximum of 3 kg ha−1 yr−1 in mineral soils.