Abstract:
We conducted a study to determine the response of Late Valencia sweet
orange to organic and inorganic fertilizer application for two seasons in the
semi-deciduous forest agro-ecological zone of Ghana. The experiment which
was conducted in a randomized complete block design with four replications
consisted of six treatments: (1) 9 t/ha oil palm empty fruit bunches (EFB); (2)
4 t/ha poultry manure (PM); (3) NPKZn (90 kg/ha N, 60 kg/ha P, 80 kg/ha
K and 4.8 kg/ha Zn); (4) 0.5 EFB (4.5 t/ha) + 0.5 NPKZn (45 kg/ha N, 30 kg/ha P,
40 kg/ha K and 2.40 kg/ha Zn); (5) 0.5 PM (2 t/ha) + 0.5 NPKZn (45 kg/ha N,
30 kg/ha P, 40 kg/ha K and 2.40 kg/ha Zn) and (6) Control. In the 2019 harvest
season, the treatment PM+NPKZn recorded the highest yield of 14.7 t/ha
while the control recorded the least yield (6.4 t/ha). In the 2020 harvest
season, fruit yield ranged from 17.3 t/ha with the NPKZn treated plots to
28.8 t/ha with the EFB treated plots. Economic analysis showed that for the
five fertilizer application treatments, the highest benefit/cost ratio was
attained with the EFB treatment for the two harvesting seasons combined.
Fertilization did not significantly affect leaf nutrient content 253 days after
application. However, leaf nitrogen (N) and potassium (K) contents were
generally higher 253 days after fertilizer application than the initial levels
while phosphorus (P) level did not change. The study suggests the need for
farmers to adopt the use of organic wastes as a soil fertility management
practice for citrus while at the same time ensuring timely control of diseases
to reduce fruit drop and improve fruit yield.
