Potassium has important physiological functions in eucalypt plantations, increasing their productivity when applied to soil via mineral fertilizers. There is interest in identifying alternative sources to KCl owing to its high cost and limited reserves. The aim of the study was to test the effect of replacing KCl with NaCl and phonolite rock powder. Two comparisons were made: (1) application of 283 kg ha⁻¹ of KCl compared with that of 2125 kg ha⁻¹ of phonolite rock powder (equivalent to 170 kg ha⁻¹ of K₂O in both treatments); (2) application of 139 kg ha⁻¹ of NaCl compared with that of 183 kg ha⁻¹ of KCl (equivalent to 2.33 kmol Na and K, respectively). Radial growth, soil water content, leaf water potential (Ψ), accumulated transpiration, stem volume and biomass increment, as well as water use efficiency (WUE) were evaluated. In the first comparison, both fertilizations presented equal values for all characteristics evaluated. In the second, the accumulated transpiration in trees fertilized with KCl was 17% higher than that in plants fertilized with NaCl. In contrast, the WUE was 20% higher in the trees fertilized with NaCl than in those fertilized with KCl, reflecting the lower water consumption for the same increment in stem volume and biomass. We conclude that phonolite rock powder and NaCl are possible substitutes for conventional K fertilization performed with KCl.

中文翻译：

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KCl，NaCl和方沸石粉施肥的桉树人工林地上生物量，蒸腾作用和水分利用效率

钾在桉树人工林中具有重要的生理功能，当通过矿物肥料施用于土壤时，钾的生产率提高。由于其成本高且储量有限，因此有兴趣寻找KCl的替代来源。该研究的目的是测试用NaCl和方沸石石粉替代KCl的效果。进行了两个比较：（1）施用283 kg ha ^-1的KCl与2125 kg ha ^-1的方沸石石粉（两种处理均相当于170 kg ha ^-1的K ₂ O）；（2）施用139 kg ha ^-1的NaCl与施用183 kg ha ^-1的NaClKCl（分别等于2.33 kmol Na和K）。评估了径向生长，土壤含水量，叶水势（Ψ），累积蒸腾作用，茎干量和生物量增加以及水分利用效率（WUE）。在第一个比较中，两种肥料的所有特性均具有相同的值。在第二个方面，用氯化钾施肥的树木的累积蒸腾量比用氯化钠施肥的植物高17％。相反，用NaCl施肥的树木的WUE比使用KCl施肥的树木的WUE高20％，这反映了在茎体积和生物量相同的情况下较低的耗水量。我们得出的结论是，方沸石岩粉和NaCl可以替代用KCl进行的常规钾肥施肥。