The effect of rock content on nutrients in a Sierra Nevada forest soil

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• 作者：D.W. Johnson ; ^{dwj@cabnr.unr.edu} ; R.F. Walker ; D.W. Glass ; W.W. Miller ; J.D. Murphy ; C.M. Stein
• 关键词：Soil ; Rock content ; Carbon ; Nitrogen ; Calcium ; Magnesium
• 刊名：Geoderma
• 出版年：2012
• 期刊代码：28_00167061
• 类别：ear
• 出版时间：March, 2012
• 卷：173-174
• 期：Complete
• 页码：84-93
• 文件大小：1618 K

摘要

The effects of rock content on nutrient concentrations and contents (kg ha^鈭?#xA0;1) in a skeletal soil derived from andesite were investigated. Rock content to a 60 cm depth ranged from 8 to 69%among 20 quantitative soil pits within a 10 ha area. On average, rocks contained 9%of total soil C, 19%of total soil N, 3%of total ecosystem C, and 12%of total ecosystem N. Percent rock content also appeared to cause increases in organic matter concentrations: rock content was significantly, positively correlated with total C and total N concentrations in the fine earth (> 2 mm) fraction. Soil C was organic; no carbonates were present. Percent rock content was also significantly, positively correlated with fine earth C:N ratio, suggesting that organic matter in rockier soils was in an earlier stage of decomposition at any given depth. Other consistent correlations with rock content included Bray P (positive) and exchangeable Mg^2 + (negative). The decrease in fine earth mass with increasing percent rock content offsets the increase in C concentration such that there was no correlation between percent rock content and either fine earth or total soil (fine earth plus rock) C content (kg ha^鈭?#xA0;1). Percent rock content was significantly negatively correlated with total N, Bray P, inorganic N, exchangeable K⁺, Ca^2 +, and Mg^2 + contents, however. The results of this study show that high rock content can affect soil C and nutrient pools not only because of the contributions of the rocks themselves, but also because high rock content appears to cause higher concentrations in the fine earth fraction.