Effect of Balanced Fertilization on Citrus

This ongoing project, initiated in 2006, continues to develop best fertilizer management practices for high yielding and quality citrus fruit. In 2006, the main nutrient limitations were identified and the effects of enhanced fertilization with Mg, Zn, and Mn were examined through field study. Since the research data in 2006 showed no significant effect for Zn and Mn, the 2007 (and 2008) experimental designs were modified to study the effects of three Mg rates (45, 83, and 120 kg Mg/ha) and B, as 45 kg borax/ha.

Results further verified the effect of Mg on citrus in 2007. Compared to the NPK treatment, yield increased by up to 24.9 t/ha (40%) with 120 kg Mg/ha. Further addition of B increased yield another 11%. All the improved fertilizer treatments significantly raised yields beyond that obtained with common farm practice. All treatments having Mg and B obviously improved fruit quality (soluble solids, soluble sugar, and vitamin C) compared to the NPK or farmer practice. This project will be terminated in 2009. Guangdong-06