Influence of Wood Vinegar and Potassium Application on Soil Properties and Ca/K Ratio in Citrus Rootstocks

Disorder in potassium (K) and calcium (Ca) uptake and Ca/K ratio in plant may affect the citrus rootstocks performance. The plant Ca/K ratio may differ among different citrus rootstocks and may be affected by wood vinegar and K application.The effect of wood vinegar (100- and 50-folds dilutions) and K application (100 mg kg−1 soil) on some soil properties, soil soluble K, Ca, and sodium (Na), and their uptake by sour orange (Citrus aurantium) and Mexican lime (Citrus aurantifolia) were studied.Wood vinegar application increased soil electrical conductivity (EC)(by 0.5 dS m−1), soluble K (by 4 mg kg−1), Ca (by 38 mg kg−1), and Ca/K ratio (by 1.2 unit) and decreased soil pH (by 0.1 unit) while K application increased soil EC (by 0.7 dS m−1), soluble K (by 44 mg kg−1), and Ca (by 14 mg kg−1) and decreased soil pH (by 0.08 unit) and Ca/K ratio (by 4.35 unit). The sour orange accumulated Ca in the roots while the Mexican lime accumulated K in the roots and leaves (1.95 and 2.01%, respectively). Potassium application caused a decrease in the Ca/K ratio in the roots and leaves while the wood vinegar increased the Ca/K ratio in the leaves. Regardless of the rootstock, wood vinegar, and K treatments, more than 50% of the Ca and K were accumulated in the leaves.Potassium addition to the sandy-textured calcareous soils is recommended for maintaining the plant Ca/K balance while addition of wood vinegar may cause a K deficiency in citrus.