Consideration of Snow Cover and Snowmelt upon the Inorganic Nitrogen Leaching Characteristics of an Apple Orchard in a Gray Lowland Soil

Abstract

The authors estimated spatiotemporal dynamics of inorganic nitrogen concentration of pore water in Apple orchard of Gray lowland soil in Tsugaru region, Aomori prefecture by numerical analysis with FEM solver, taking snow cover and snowmelt into account. Under non-consideration condition of snow cover and snowmelt, it was indicated that the traveling velocity (Δz/Δt) of the NO₃-N concentration peak reached to a depth of 100 cm (Δz/Δt = 20-26 cm/month) in about 4 months from late November to the early March of the following year. On the other hand, considering snow cover and snowmelt, it was indicated that the high concentration of NO₃-N reached to the depth of 100 cm (Δz/Δt = 100-130 cm/month) in just one month from early March to early April. Consequently, from the perspective of promoting environmental conservation and reducing the environmental load, the importance of soil moisture transfer during winter season was quantified by numerical analysis. Thus, it was necessary to discuss the behavior of NO₃-N in soil pore water and the nitrogen budget, taking into consideration the snowmelt water from the soil surface in early spring.