| Popis: |
To investigate some of the effects of standing stubble on microclimate and on the energy and water balance in relation to plant development, winter wheat (Triticum aestivum L.) was seeded directly into spring wheat stubble of three heights: 0 (bare), 15–19, and 30–35 cm. The soil near Sidney, Montana was Williams loam (fine-loamy mixed, frigid family of Typic Argiborolls) a bench mark soil for dryland cropping in the northern Great Plains of the U.S.A. Total wind passage at 9 cm above ground level was 1.5 and 5 times greater over bare as compared with that over short and tall stubble, respectively. Snow accumulation after a late winter storm was 2 and 4 times greater on short and tall stubble treatments, respectively, than on the bare plots. The first overwinter soil recharge was 3 cm more on both stubble treatments, a difference that persisted throughout the growing season. The second overwinter recharge was ca. 1.5 and 4 cm more on short and tall treatments, respectively. Midday net radiation was as much as 15% higher over the bare treatment in the fall and varied from 5 to 11% lower over the bare treatment in the spring, as compared with that over stubble. Stubble albedo was as much as 1.5 times greater than bare albedo in the fall; differences in the spring were small. On heating days, maximum soil surface temperatures were as much as 10°C higher on bare as compared with stubble treatments and soil heat flow as much as 30% greater on bare as compared with stubble treatments; on freezing days, heat flow differences were small. |
