Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA.
Plant and Soil Sciences Department, Oklahoma State University, Stillwater, OK, USA.
Sci Rep. 2024 Sep 2;14(1):20377. doi: 10.1038/s41598-024-71381-8.
Portable X-ray Fluorescence probe (pXRF) is a tool used to measure many elements quickly and efficiently in soil with minimal sample preparation. Although this sensing technique has been widely used to determine total elemental concentrations, it has not been calibrated for plant-available nutrient predictions. We evaluated the potential of using pXRF for fast plant-available nutrient quantification. Two experiments were conducted in soils treated with two types of biochars to obtain a practical range of soil pH (5.5 - 8.0) and organic carbon (2.0 - 5.5%). Biochars applied were derived from switchgrass (SGB) and poultry litter (PLB). The first experiment received biochars at application rates up to 8% (w/w) and had no plants. The second experiment had up to 4% of SGB or PLB planted with ryegrass (Lolium perenne). Linear regression (LR), polynomial regression (PolR), power regression (PowR), and stepwise multiple linear regression (SMLR) were the models tested. Regardless of the extraction method, phosphorus (P) showed a strong relationship between pXRF and several laboratory extraction methods; however, K prediction via pXRF was sensitive to the plant factor. The optimum soil available-P corresponding to the maximum P uptake in plant tissues can be assessed with pXRF. The LR was inconsistent for calcium (Ca), sulfur (S), and copper (Cu) and non-significant for magnesium (Mg), iron (Fe), and zinc (Zn). Our results showed that pXRF is applicable to estimate P availability in soils receiving organic amendments. More evaluations are needed with diverse soil types to confirm the findings before using pXRF for fertilizer recommendation.
便携式 X 射线荧光探针（pXRF）是一种用于快速、高效地测量土壤中多种元素的工具，只需进行最小量的样品制备。尽管这种传感技术已被广泛用于测定全元素浓度，但尚未针对植物有效养分预测进行校准。我们评估了使用 pXRF 快速定量植物有效养分的潜力。在两种用生物炭处理的土壤中进行了两项实验，以获得实际范围内的土壤 pH（5.5-8.0）和有机碳（2.0-5.5%）。应用的生物炭分别来自柳枝稷（SGB）和家禽粪便（PLB）。第一项实验中，生物炭的施用量高达 8%（w/w），且无植物。第二项实验中，在高达 4%的 SGB 或 PLB 上种植黑麦草（Lolium perenne）。线性回归（LR）、多项式回归（PolR）、幂回归（PowR）和逐步多元线性回归（SMLR）是测试的模型。无论采用哪种提取方法，pXRF 与几种实验室提取方法之间均显示出磷（P）的强相关性；然而，pXRF 预测 K 与植物因素有关。可使用 pXRF 评估与植物组织中最大 P 吸收相对应的最佳土壤有效 P。LR 对钙（Ca）、硫（S）和铜（Cu）的预测不一致，对镁（Mg）、铁（Fe）和锌（Zn）的预测则不显著。我们的结果表明，pXRF 适用于估算接受有机改良剂的土壤中 P 的有效性。需要对更多不同类型的土壤进行评估，以在使用 pXRF 进行肥料推荐之前确认这些发现。
