Straw Color for Altering Soil Temperature and Heat Flux in the Subarctic

Abstract

AbstractIn the Subarctic, straw management methods are needed that improve the early season soil thermal environment of conservation tillage systems. This study determined whether soil heat and water flux are influenced by barley (Hordeum vulgare L.) straw color. Surface temperatures, thaw depth, and latent, sensible, and soil heat flux were ascertained for soil‐black straw, soil‐white straw, and soil‐natural straw surfaces during the spring of 1988 to 1990 at Fairbanks, AK. Daily soil temperatures at 0.05 m, soil surface heat flux, and thaw depth were as much as 0.5°C, 0.5 MJ m−2, and 10 mm greater, respectively, for the black straw than for the other straw color treatments. An atmosphere‐snow‐straw‐soil system model predicted greater absorption of radiation by the soil‐black straw surface, although the percentage of net radiation partitioned to soil heat was lower for the soil‐black straw surface than for the soil‐natural straw and soil‐white straw surfaces. Simulation indicated that straw color did not influence the proportion of absorbed radiation utilized in latent heat flux, but the black straw treatment had the greatest percentage of net radiation partitioned into sensible heat flux. Although the soil thermal environment was slightly altered by changing straw color, managing straw color in conservation tillage systems may aid little in optimizing the thermal regime of subarctic soils unless methods are employed to minimize sensible heat loss from the soil‐straw surface.