Maize (Zea mays L.) is one of the most susceptible crops to zinc (Zn) deficiency. However, in much of the world, soil Zn tests are poorly calibrated, and thus determining a critical soil test, level for Zn is challenging. The objectives of this study were to: (i) produce a field calibration of the Zn Mehlich-3 (M3-Zn) method for predicting maize grain yield response to Zn fertilizer application, (ii) compare the capacity of DTPA extractable Zn (DTPA-Zn) with M3-Zn for predicting the response of maize yield to Zn fertilizer, (iii) determine whether inclusion of soil pH, organic matter (SOM) and extractable phosphorus in a M3-Zn model improves its predictive capacity and (iv) evaluate an economic approach for determining soil Zn thresholds. We conducted 55 field experiments covering a wide range of edaphic and climatic conditions. Maize responded to Zn fertilizer in 29% of the trials. The capacity of M3-Zn and DTPA-Zn to predict relative yield of maize was similar. Inclusion of other soil variables (pH, extractable phosphorus and SOM) did not or only slightly improve the prediction of M3-Zn. Based on the relationship between M3-Zn and DTPA-Zn (R² = 0.89), one test can be predicted from the other without affecting the calibration. The M3-Zn 'economic threshold' ranged from 0.98 to 2.79 mg kg⁻¹, while for DTPA-Zn it varied from 0.41 to 1.61 mg kg⁻¹. The broad range of economic thresholds shows that differences in maize productivity and grain price between regions and seasons make establishing a single Zn threshold for all economic-productive situations inappropriate.

中文翻译：

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确定 Mehlich-3 和 DTPA 可提取土壤锌对玉米的最佳经济阈值

玉米（Zea maysL.) 是最易受锌 (Zn) 缺乏症影响的作物之一。然而，在世界大部分地区，土壤锌测试的校准很差，因此确定关键的土壤测试，锌的水平具有挑战性。本研究的目的是：(i) 对 Zn Mehlich-3 (M3-Zn) 方法进行田间校准，以预测玉米籽粒产量对锌肥施用的响应，(ii) 比较 DTPA 可提取锌 (DTPA) 的能力-Zn) 与 M3-Zn 用于预测玉米产量对锌肥的响应，(iii) 确定在 M3-Zn 模型中包含土壤 pH、有机质 (SOM) 和可提取磷是否会提高其预测能力，以及 (iv)评估确定土壤锌阈值的经济方法。我们进行了 55 次田间试验，涵盖了广泛的土壤和气候条件。在 29% 的试验中，玉米对锌肥有反应。M3-Zn 和 DTPA-Zn 预测玉米相对产量的能力相似。包含其他土壤变量（pH、可提取磷和 SOM）并没有或仅略微改善 M3-Zn 的预测。基于M3-Zn与DTPA-Zn的关系（R ²  = 0.89)，一个测试可以从另一个预测而不影响校准。M3-Zn“经济阈值”的范围为0.98 至2.79 mg kg ^-1，而DTPA-Zn 的范围为0.41 至1.61 mg kg ^-1。广泛的经济阈值表明，地区和季节之间玉米生产力和粮食价格的差异使得为所有经济生产情况建立单一的锌阈值是不合适的。