Abstract

Mobile proximal gamma-ray spectrometry (GS) is an emerging approach to estimate soil texture directly in the field. It relies on gamma radiation emitted during the natural decay of potassium-40 (K-40) and other isotopes. The K-40 counts are correlated with total K content, mineralogical soil composition and therefore with soil texture. Yet, it is not clear if K fertilisation impacts the ratio of K-40 to total K which would necessitate to take the fertilisation history into account for soil sensing applications. To elucidate this question, a well-documented long-term experiment was selected. The soils of the Rengen grassland experiment (55 plots) were investigated for total K (XRF-K) and for K-40 via mobile proximal GS. No significant differences in XRF-K and K-40 were found between the treatments with and without K fertilisation, although formely published results point to negative and positive K balances, respectively. Fertiliser analysis revealed a ratio of K-40 to total K that was almost identical to the natural abundance of 0.0117%. It was concluded that it is not necessary to take K fertilisation history into account when predicting soil texture from mobile proximal GS on agricultural land for, e.g., precision farming purposes.

中文翻译：

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钾肥对移动近端伽马射线能谱测定的影响：长期现场试验的案例研究

摘要

移动近端伽马射线能谱测定 (GS) 是一种直接在现场估算土壤质地的新兴方法。它依赖于钾 40 (K-40) 和其他同位素自然衰变过程中发出的伽马辐射。K-40 计数与总钾含量、土壤矿物成分以及土壤质地相关。然而，尚不清楚施钾是否会影响 K-40 与总钾的比例，这需要在土壤传感应用中考虑施肥历史。为了阐明这个问题，我们选择了一项有据可查的长期实验。通过移动近端 GS 对 Rengen 草原实验（55 个地块）的土壤进行了总钾 (XRF-K) 和 K-40 的调查。尽管之前发表的结果分别表明钾肥负平衡和正钾平衡，但在施钾和未施钾的处理之间，XRF-K 和 K-40 没有显着差异。肥料分析显示 K-40 与总钾的比率几乎与 0.0117% 的自然丰度相同。结论是，在出于精准农业等目的从农业用地上的移动近端 GS 预测土壤质地时，没有必要考虑施钾历史。