It is critical to have a soil test that allows for the measurement of potential toxicity. A laboratory experiment was undertaken to investigate the effects of changing the concentration of salt in the extract and extraction time of the standard CaCl₂ and KCl soil Al tests on the Al concentrations extracted from 13 soils from four New Zealand soil orders. Al extracted by KCl (Al_KCl) was 13 times higher than extracted by CaCl₂ (Al_CaCl2) across all soils. The effect of changing extract salt concentration and extraction time on Al extracted differed among the four soil orders tested for the two extraction methods. Increasing the concentration of CaCl₂ in the extract increased (P < .001; P < .05) the amount of Al_CaCl2 (by 0.02–0.13 cmol_c/kg) for the four soil orders, while increasing extraction time resulted in a difference only in the Allophanic soils, where Al_CaCl2 decreased (P < .01). The interaction of the concentration of salt in the extract and extraction time for the CaCl₂ extraction did not affect (P > .05) the Al_CaCl2 extracted from all soils. An increase in the concentration of KCl in the extract up to 1 M increased Al_KCl (P < .01) (by 0.2–0.8 cmol_c/kg) on the Allophanic, Brown and Pumice soils, with no increase (P > .05) with a further increase in concentration. Extraction time affected Al_KCl (P < .001) for Pallic soils, while the interaction of concentration of KCl in the extract and extraction time resulted in differences (P < .001) only for the Pallic soils. These findings suggest that the Al concentrations measured by the two extraction methods are affected by specific soil properties in the topsoil related to soil order. This means that when measuring the Al bioavailability in soils, extreme care must be taken when interpreting soil Al test results.

进行土壤测试以测量潜在毒性至关重要。进行了一项室内实验，以研究改变标准CaCl ₂和KCl土壤Al试验中提取盐浓度和提取时间对从四个新西兰土阶的13种土壤中提取的Al浓度的影响。在所有土壤中，用KCl提取的Al（Al _KCl）比用CaCl ₂（Al _CaCl2）提取的Al高13倍。对于两种提取方法测试的四个土壤阶次，改变提取盐浓度和提取时间对提取的Al的影响有所不同。增加提取物中CaCl ₂的浓度会增加（P <.001; P  <.05）四个土壤阶的Al _CaCl2量（降低0.02–0.13 cmol _c / kg），而增加的提取时间只会导致异源土壤的铝_CaCl2减少（P  <.01） 。提取物中盐浓度与提取CaCl _2的时间之间的相互作用不会影响从所有土壤中提取 的Al _CaCl2（P > .05）。在Allophanic，Brown和Pumice土壤上，提取物中的KCl浓度增加至1 M时，Al _KCl含量增加（P  <.01）（0.2-0.8 cmol _c / kg），而没有增加（P  > .05），浓度进一步提高。萃取时间影响 了棕壤中的Al _KCl（P <.001），而萃取物中KCl浓度与萃取时间的相互作用 仅对棕壤有差异（P <.001）。这些发现表明，通过两种萃取方法测得的铝浓度受表层土壤中与土壤秩序有关的特定土壤特性的影响。这意味着在测量土壤中的铝生物利用度时，在解释土壤铝测试结果时必须格外小心。