The response of date palm to calcareous soil fertilisation
An experiment was conducted during two successive seasons, 2008/2009 and 2009/2010, on the Zaghloul date palm cultivar grown in calcareous loamy sand and irrigated with drainage water. The purpose of the experiment was to investigate the effects of 1,000 g total N per palm applied as either ammonium sulphate, ammonium nitrate or urea and two levels of potassium (K2O) and elemental sulphur (S) on the nutritional status, productivity and fruit quality of the cultivar. The results of the study showed that the ammonium sulphate form (N1) increased the fruit yield, weight, length and colour compared to the ammonium nitrate (N2) or the urea form (N3). Fruit TSS, sugars, anthocyanin and dry matter content increased, whereas fruit acidity and tannins decreased under N1 fertilisation. Furthermore, the potassium and sulphur fertilisation enhanced the physico-chemical characteristics of the fruit. The N1 application increased the leaf N, K, Ca, Fe and Zn contents, as did the potassium and sulphur application. The N1 application increased the fruit N, P, K, Fe and Zn contents, whereas the fruit Cd, Pb and NO3 were highest with N2. The potassium and sulphur applications increased the fruit N, Fe, Mn, Cd, Pb and NO3 contents.