Effects of a snow-compaction treatment on soil freezing, snowmelt runoff, and soil nitrate movement: A field-scale paired-plot experiment

• Published in: Journal of hydrology (Amsterdam) Vol. 567; pp. 280 - 289
• Main Authors: Iwata, Yukiyoshi, Yanai, Yosuke, Yazaki, Tomotsugu, Hirota, Tomoyoshi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2018
• Subjects: Nitrate leaching; NO3-N; Runoff ratio; Snow compaction; Snowmelt infiltration; Soil frost depth; Snowmelt infiltration; Soil frost depth; Nitrate leaching; Snow compaction; NO3-N; Runoff ratio
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/j.jhydrol.2018.10.016

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•Snow-compaction treatment produced a thick frozen soil layer during the winter months.•This thick frozen layer induced large amounts of snowmelt runoff.•Larger snowmelt runoff resulted in greater nitrate content in the plow layer in early spring.•With snow-compaction treatment, farmers can increase nitrate in the plow layer.•Nitrate percolation to ground water may be reduced by this treatment in northern Japan.
A frozen soil layer may impede snowmelt infiltration, resulting in a large amount of runoff that influences the soil water balance and anion movement in the soil profile. To examine the relationships among soil frost depth, snowmelt runoff, and nitrate leaching in agricultural fields, we measured both the snowmelt runoff for three winters and other environmental factors including the soil frost depth and nitrate content in a ∼10,000 m2 field. We divided the field into two subplots: one was maintained in a natural snow cover condition (the control plot), and the snow cover was compacted on the other plot (the treated plot) to enhance the development of the soil frost depth. In all three winters, soil frost depths in the control plot were <0.2 m and very little runoff was observed during the snowmelt period. In contrast, the soil frost depth became >0.4 m and a large amount of snowmelt runoff was observed in the treated plot. The depth of the peak nitrate concentration after the snowmelt period was shallower in the treated plot compared to the control plot. Moreover, a significant linear relationship was observed between (1) the amount of nitrate in the 0–0.3 m depth after the snowmelt period and (2) the total amount of snowmelt infiltration calculated by subtracting the amount of snowmelt runoff from the amount of snowmelt water. These results suggest that snow compaction can be a promising technique to develop a uniform soil frost depth in large-scale fields, which consequently controls the soil water and nutrient movement in the soil layer.