Early farmers used at least two types of agrarian amendments that could raise pH and base saturation levels to allow the cultivation of cereals: marling and plant ash. Ash can be input in many different ways: felling and burning in place, transferring plant material from wastelands and spreading the ash, charring sod or peat blocks, burning stubble after harvest. Marling includes all the practices of amending limestone, from marl to chalky limestone composed of 99% CaCO₃. In order to understand the evolution of these agricultural practices, it is important to identify which of the two techniques was used to amend cereal crops in the past. In order to test the potential of δ^44/40Ca-δ^88/86Sr-⁸⁷Sr/⁸⁶Sr multiple isotope approach for archaeological samples, we first applied the technique to currently grown crops, amended either with marl or with ash from freshly-cut and burned trees. We found that this approach makes it possible to discriminate cereal grains amended either by marling (less radiogenic Sr) or with tree ash (more radiogenic Sr). We also identified a positive correlation between stable Ca and Sr isotope values, suggesting that the Ca and Sr came from similar sources and had undergone similar mass-dependent isotopic fractionation mechanisms. Consequently, we later on mainly focused on stable and radiogenic Sr isotopes. Stable Sr isotope fractionation was also observed between different locations, different organs of a given cereal species and between different cereal types, but also within the same cereal species or the number of grains studied for a given locality, pointing to biological fractionation combined with source variation.

早期农民至少使用两种类型的土地改良剂来提高 pH 值和碱饱和度以种植谷物：泥灰岩和草木灰。灰烬可以通过多种不同的方式输入：就地砍伐和燃烧、从荒地转移植物材料并撒播灰烬、炭化草皮或泥炭块、收获后焚烧残茬。马林包括改良石灰石的所有做法，从泥灰岩到由 99% CaCO ₃组成的白垩石灰石。为了了解这些农业实践的演变，重要的是要确定过去使用这两种技术中的哪一种来改良谷类作物。为了测试δ ^44/40 Ca-δ ^88/86 Sr- ⁸⁷ Sr/ ^86的潜力对于考古样本的多同位素方法，我们首先将该技术应用于当前种植的农作物，并用泥灰或新砍伐和烧毁的树木的灰烬进行修正。我们发现，这种方法可以区分通过泥灰岩（放射源性较低的 Sr）或树灰（放射源性较高的 Sr）改良的谷物。我们还发现稳定的 Ca 和 Sr 同位素值之间存在正相关性，这表明 Ca 和 Sr 来自相似的来源并且经历了相似的质量依赖性同位素分馏机制。因此，我们后来主要关注稳定的放射性锶同位素。在不同地点、给定谷物品种的不同器官之间以及不同谷物类型之间，而且在同一谷物品种或给定地点研究的谷物数量内也观察到稳定的锶同位素分馏，表明生物分馏与来源变化相结合。