Acidification of agricultural soils under intense management in the Palouse region of eastern Washington and northern Idaho is of increasing concern. Buffer methods can provide lime requirement estimates (LREs); however, locally calibrated methods are lacking. Our objective was to evaluate buffer methods and to determine which can produce optimal LREs for Palouse agricultural soils. Samples from 10 regionally dominant agricultural soils (initial pH ≤5.3) were assessed for pH changes after incubation with nine levels of calcium carbonate (CaCO₃) for 90 d under laboratory conditions. Achieving a target pH of 6 in the top 15 cm of the soil profile required 3.36–8.36 Mg ha⁻¹ of CaCO₃. Laboratory incubation results were compared with LREs calculated from 10 established calibrations using data from seven buffer methods: Shoemaker–McLean–Pratt (SMP), Adams and Evans (AE), Woodruff 6, Woodruff 7, Western Region Woodruff 7, Sikora, and Modified Mehlich (MM). The SMP (R² = .47) and AE (R² = .56) calibrations demonstrated the lowest correlation with observed incubation lime requirement (LR) and are not recommended for use on Palouse soils. The MM (R² = .90), Woodruff 6 (R² = .78), and Woodruff 7 (R² = .75) buffer calibrations produced the strongest correlation between LREs and the LRs determined by laboratory incubation. Combining organic matter (OM) with KCl‐extractable aluminum (KCl‐Al) or soil pH was also predictive of LR (R² = .72) in a stepwise multivariate analysis. The recommendation from this study is to assess LR on Palouse soils using the MM buffer or to use soil analytical results and compute LR from OM and KCl‐Al or pH.

中文翻译：

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确定帕卢斯酸化农业土壤上的石灰需求量的评估缓冲方法

在华盛顿东部和爱达荷州北部的帕卢斯地区，受到严格管理的农业土壤酸化问题日益引起人们的关注。缓冲方法可以提供石灰需求量估计值（LRE）；但是，缺乏本地校准的方法。我们的目标是评估缓冲方法，并确定哪种方法可以为Palouse农业土壤产生最佳的LRE。在实验室条件下，将九种碳酸钙（CaCO ₃）孵育90 d后，评估了来自10个区域优势农业土壤（初始pH≤5.3）的样品的pH变化。在土壤剖面的顶部15 cm达到6的目标pH值需要3.36–8.36 Mg ha ^-1的CaCO ₃。将实验室培养结果与使用七个缓冲方法的数据从10个既定校准中计算出的LRE进行了比较：Shoemaker–McLean–Pratt（SMP），Adams和Evans（AE），Woodruff 6，Woodruff 7，Western Region Woodruff 7，Sikora和Modified梅利希（MM）。SMP（R ²  = .47）和AE（R ²  = .56）校准与观察到的孵化石灰需求（LR）的相关性最低，因此不建议在Palouse土壤上使用。MM（R ²  = .90），Woodruff 6（R ²  = .78）和Woodruff 7（R ² = .75）缓冲液校准产生了LRE和LR（通过实验室孵育确定）之间的最强相关性。在逐步多变量分析中，将有机物（OM）与可萃取KCl的铝（KCl-Al）或土壤pH值结合也可预测LR（R ²  = .72）。该研究的建议是使用MM缓冲液评估帕卢斯土壤上的LR，或者使用土壤分析结果并根据OM和KCl-Al或pH计算LR。