Water and Solute Transport during a Winter to Snow Melt Term in an Andisol of a Thick Snow Region

Abstract

This study was conducted to investigate water and solute transport during a winter to snow melt term at a thick snow region of an Andisol. Solution of potassium bromide was sprayed as a tracer at a beginning of the winter to a fi eld where onion had been harvested in autumn. The soil was relatively dry during the winter due to surface soil freezing and internal drainage. Soil became wet and water flow bypassing soil matrix occurred in the subsoil during the snow melt term. Leaching depth of bromide ion (Br) was longer than infiltration length of water calculated by piston flow model during the early stage of the snow melt term and the leaching depth of Br was shorter than the infiltration length during the latter stage of the snow melt term. Amount of water entered the soil surface during the winter to snow melt term was equivalent to the pore space of the soil to a depth of 1m. However, Bf was not leached out completely and 32% of Bf remained in the soil shallower than 1m. Amount of nitrate nitrogen leached from 1m-soil was 198kg N ha^-1 which must be larger than nitrogen uptake by onion plant.