This investigation was carried out during 2006/2007 and 2007/2008
seasons to study the effects of organic fertilization either alone or combined
with inorganic nitrogen fertilizer on growth, fruit set %, fruit characters, yield
and leaf mineral content of date palm "Seewy cv." grown in sandy loamy soil.
Organic manure was applied at 0.0, 25, 50, 75 and 100% of the recommended
dose of nitrogen fertilization (1300g/ palm/year) combined with inorganic
nitrogen (ammonium nitrate 33.5% N) at 100, 75, 50, 25 and 0.0%,
respectively.
The obtained results showed that application of organic nitrogen alone
or combined with inorganic nitrogen significantly increased pinnae area and
leaf area but decreased leaf length and new leaf number per palm. Organic
nitrogen increased fruit set percentage in the second season. Bunch number,
bunch weight and yield per palm increased with increasing organic nitrogen
level from 50% to 100% of whole nitrogen dose/palm. Organic manure
increased fruit weight, fruit size, dry matter percentage, total sugars, reducing
sugars and total soluble solids. Total acidity and tannis were decreased by
application of organic nitrogen. Results also revealed that organic manure
increased N, P, K, Mg, Ca, Fe, Zn and Mn in pinnae content.
Finally, it is concluded that replacing 75% of nitrogen requirements for
Seewy date palms grown in sandy loamy soil by organic manure added once at
winter season was very useful in improving growth nutritional status of palms.
In addition, this treatments gave high yield with good fruit quality as well as
minimize the production cost and environment pollution which occurred by
chemical fertilizers.