Difficulties forecasting cation exchange processes may limit the use of soil solution analyses in routine soil testing for agriculture. An important part of those difficulties is the need for much data and expertise to parameterise existing models that can be used for variable charge soils. This paper proposes an algorithm to simulate concentrations of the major nutrient cations in the soil solution. It is designed to have only modest data requirements, be applicable for variable charge soils, and be simple to implement in crop and environment simulation packages. It is based on a Gaines–Thomas type approach to cation exchange, adapted to allow for variations in cation exchange capacity. It includes interactions with anions and anion exchange, which may affect cation behaviour in variable charge soils. Assumptions and limitations of the approach are described, and some issues associated with parameterisation, implementation, and future extension are discussed.

中文翻译：

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一种计算土壤溶液阳离子组成的算法。一、理论与结构

预测阳离子交换过程的困难可能会限制土壤溶液分析在农业常规土壤测试中的使用。这些困难的一个重要部分是需要大量数据和专业知识来参数化可用于可变电荷土壤的现有模型。本文提出了一种模拟土壤溶液中主要养分阳离子浓度的算法。它被设计为只有适度的数据要求，适用于可变电荷土壤，并且易于在作物和环境模拟包中实施。它基于 Gaines-Thomas 类型的阳离子交换方法，适用于允许阳离子交换容量的变化。它包括与阴离子和阴离子交换的相互作用，这可能会影响可变电荷土壤中的阳离子行为。