Nitrogen dynamics in humus and soil beneath Sitka spruce (Picea sitchensis(Bong.) Carr.) planted in pure stands and in mixture with Scots pine (Pinus sylvestrisL.)
✍ Scribed by B. L. Williams
- Publisher
- Springer
- Year
- 1992
- Tongue
- English
- Weight
- 601 KB
- Volume
- 144
- Category
- Article
- ISSN
- 0032-079X
No coin nor oath required. For personal study only.
✦ Synopsis
Sitka spruce planted on nutrient-poor soils in mixture with pine or larch, unlike pure spruce, does not become N deficient and does not require N fertilizer. To test the hypothesis that N availability in the soil is enhanced beneath mixed species, the seasonal changes in different N forms were compared in humus (L + F ÷ H) and soil beneath 15-year-old Sitka spruce (SS) and mixed Sitka spruce-Scots pine (SS and SP) planted on a gleyed heathland soil. Amounts of mineral and organic N extracted from humus in spring were significantly (p <0.05) higher in SS and SP than in SS. Larger amounts were measured in the underlying soil, which favoured the deeper-rooting spruce and pine in SS and SP plots. Annual net N mineralization, measured by in-situ incubation, was 32 and 47 kg N ha r in the surface 10 cm beneath SS and (SS and SP), respectively. In spring, readily mineralized organic N (waterlogged incubation at 30°C) was higher in humus and soil from (SS and SP) than from SS by 15 kgN ha -~. The larger N pools beneath (SS and SP) were consistent with the higher total N content of the humus beneath (SS and SP), 446 compared with 255 kg N ha -~ beneath SS. This indicated that beneath (SS and SP) N had been transferred from the underlying soil.