EFFECTS OF NITROGEN AND POTASSIUM FERTILIZER ON GROWTH PERFORMANCE AND YIELD OF CASSAVA (Manihot esculenta Crantz) IN THE DERIVED SAVANNA ZONE OF DELTA STATE, NIGERIA

This study was conducted to evaluate the influence of Nitrogen (N) and Potassium (K) fertilizers
on the growth and yield performance of Cassava (Manihot esculenta) at Igbodo (5°45′N, 6°30′E)
in Delta State, Nigeria. The experiment utilized a 4×4 factorial design within a Randomized
Complete Block Design (RCBD), replicated three times. The following treatment combinations
were applied N0K0kg/ha, N0K20kg/ha, N0K40kg/ha, N0K80kg/ha, N40K0kg/ha, N40K20kg/ha,
N40K40kg/ha, N40K80kg/ha, N80K0kg/ha, N80K20kg/ha, N80K40kg/ha, N80K80kg/ha, N120K0kg/ha,
N120K20kg/ha, N120K40kg/ha and N120K80kg/ha. Soil samples were analyzed for physic-chemical
properties, and cassava variety 01/1797 was planted. Growth parameters such as plant height,
leaf number, and leaf area were measured at 2, 4, 6, 8, and 10 months after planting (MAP).
Yield data, including fresh tuber weight, dry matter content, and peel weight were also recorded.
Soil analysis revealed a slightly acidic, loamy sand with a pH of 4.72, deficient in organic
Carbon, Nitrogen, Potassium, Calcium, and Magnesium, but moderate in micronutrients like
Zinc, Iron, Copper, and Manganese. Fertilizer applications of N and K significantly improved
plant growth and yield. The combination of 80 kg N+80 kg K/ha produced the best results and
is recommended for cassava cultivation in Igbodo. However, a decline in soil organic carbon
post-harvest suggests that organic amendments (such as application of manure) should
complement mineral fertilizers to enhance soil quality.