Soil color and surface residue effects on seedling light environment

Summary

The quantity and spectral distribution (quality) of reflected light 10 cm above dry, wet and plant residue-covered soils were compared over black, brick-red, and gray-white soils. Photosynthetic photon flux density of reflected light ranged from about 4% of direct sunlight over bare, wet black soil to 21% over dry near-white soil. Plant residue on the soil surface increased the reflected light over the black soil and decreased it over the light-colored soils. The amount of reflected blue light was greatest over the whitest soil. When soil temperature differences were eliminated by insulation panels, stems of southern pea [Vigna unguiculata (L.) Walp.] seedlings elongated less over white surfaces than over black surfaces.