Simulation of Nitrate Leaching from Arable Land in Southern Sweden

Abstract

Soil nitrate dynamics and nitrate leaching were simulated for a nine-year period. Hydrological time-series, previously simulated with a soil water and heat model were used as driving variables. Parameter values were derived from measurements and management practices or adapted from other comparable applications. Model outputs were tested against measurements of leaching and nitrate content of the soil. Dominating crops were spring wheat, barley and sugar beets but also winter wheat and winter rape were grown. Predictions of nitrate in the soil were good on six of eight occasions. Simulated yearly leaching was close to measured values in most years. The deviations could be explained by model failure in predicting surface runoff and uncertainties in the nitrogen harvest. The between-year variation in the leaching magnitude during years with ‘normal' discharge rates could largely be explained by the amount of nitrate remaining in the soil profile in the beginning of September and the litter mineralization during the period September-March. Years with higher or lower discharge rates compared to ‘normal’ resulted in increased or decreased nitrate leaching, respectively, compared to normal for the same amount of mineral nitrogen available for leaching.

Key Words:

• soil nitrate
• numerical model
• nitrogen crop uptake
• N-mineralization
• N-deposition