Response of Bitterbrush Seedlings to Nitrogen and Moisture on a Granitic Soil1
- J. O. Klemmedson and
- R. B. Ferguson2
Greenhouse studies were conducted to explore the influence of nitrogen and moisture on seedlings of bitterbrush (Purshia tridentata [Pursh] DC.), when grown in soil from three different layers. Seedlings were grown in pots in granitic soil collected from 0–15-, 15–40-, and 40–90-cm soil layers with three nitrogen (N) treatments (0, 34, and 100 kg/ha) and low and high moisture regimes. Shoot and root weights of seedlings grown in surface soils without added N greatly exceeded those for seedlings grown in soil from lower layers. Added N caused seedling yields to decline on surface soils but to increase on the 40–90-cm soil layer. Maintenance of a high moisture regime diminished the adverse effects of added N on seedlings grown in soil from the surface layer, but improved its effectiveness on seedlings grown in lower layer soils. Shoot-root ratios and efficiency of water use by bitterbrush differed with respect to N and soil layer treatments. In subsequent experiments, six granitic soils (including the previously tested soil) proved deficient in N for barley. However, on the same soils, bitter-brush responded negatively or gave no response to added N. The experiments showed that yields of bitterbrush declined when N in plants reached about 2.0%.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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