Iron (hydr)oxide crystallinity effects on soil aggregation
Iron (hydr)oxide crystallinity effects on soil aggregation
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DOI：
10.2136/sssaj2003.0606
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发表时间：
2003-03-01
影响因子：
2.9
通讯作者：
Lal, R
中科院分区：
文献类型：
--
作者：
Duiker, SW;Rhoton, FE;Lal, R
结晶度的差异可以解释为什么总铁（氢）氧化物含量对聚集体稳定性有可变的影响。因此，对具有一系列低结晶氧化铁含量的表层土壤样品进行了水稳性团聚体>0.25 mm（WSA）、平均加权直径（MWD）、土壤有机碳（OC）、粒度分布、pH、可交换阳离子、柠檬酸盐/碳酸氢盐/连二亚硫酸盐（下标d）和酸性草酸铵（下标o）可提取的铁、铝和硅的表征。WSA和MWD的范围分别为23 - 95%和0.3 - 5.1 mm。采用线性回归方法研究了Fe-o（1.1-6.8 g kg（-1））、Fe-d（3.2-19.6 g kg（-1））、OC（2.4-24.0 g kg（-1））和粘粒（141-467 g kg（-1））含量对A、B层WSA和MWD的影响。在A层（r（2）= 0.95，n = 6，p = 0.001，r（2）= 0.93，n = 6，p = 0.002）和B层（r（2）= 0.73，n = 6，p = 0.029，r（2）= 0.76，n = 6，p = 0.024）。当相对于MWD回归时，Fe-0在A层中的r（2）为0.89（n = 6，p = 0.004），在B层中的r（2）为0.97（n = 6，p = 0.000）。A层和B层的MWD与OC含量的决定系数分别为0.98（n = 6，p = 0.000）和0.79（n = 6，p = 0.018）。粘粒和Fe-d含量与WSA和MWD的相关性不显著。显然，Fe-O组分（结晶性差）在稳定土壤团聚体方面比Fe-D更有效，即使它以较低浓度存在。对于有机质含量较低的土壤，铁氧组分在水稳性和分子量分布上比有机碳更为重要。
Differences in crystallinity may explain why total Fe (hydr)oxide content has a variable effect on aggregate stability. Therefore, surface soil samples with a range of poorly crystalline Fe (hydr)oxide contents were characterized for water-stable aggregates >0.25 mm (WSA), mean-weighted diameter (MWD), soil organic C (OC), particle-size distribution, pH, exchangeable cations, citrate/bicarbonate/dithionite (subscript d), and acid ammonium oxalate (subscript o) extractable Fe, Al, and Si. The WSA and MWD range from 23 to 95%, and 0.3 to 5.1 mm, respectively. The effects of Fe-o (1.1-6.8 g kg(-1)), Fe-d (3.2-19.6 g kg(-1)), OC (2.4-24.0 g kg(-1)) and clay (141-467 g kg(-1)) contents on WSA and MWD of both A and B horizons of these soils was studied using linear regression. The poorly crystalline Fe (hydr)oxide (Fe-o) and OC contents are significantly correlated with WSA in the A horizons (r(2) = 0.95, n = 6, p = 0.001, and r(2) = 0.93, n = 6, p = 0.002, respectively) and in the B horizons (r(2) = 0.73, n = 6, p = 0.029, and r(2) = 0.76, n = 6, p = 0.024, respectively). When regressed against MWD, Fe-o has an r(2) of 0.89 (n = 6, p = 0.004) in the A, and 0.97 (n = 6, p = 0.000) in the B horizons. The coefficient of determination of MWD vs. OC contents is 0.98 (n = 6, p = 0.000) in the A and 0.79 (n = 6, p = 0.018) in the B horizons. Clay and Fe-d contents are not significantly correlated to WSA or MWD. Apparently, the Fe-o component (poorly crystalline) is more effective than Fe-d at stabilizing soil aggregates, even though it is present in lower concentrations. The Fe-o component appears more important than OC in terms of WSA and MWD for soils with relatively low soil organic matter contents.