ABSTRACT
Laboratory, greenhouse and field studies were undertaken to investigate
the status of Cu and Zn and to find out whether the addition of these nutrient
elements in soils would increase maize grains and yield components and also,
remediate their constraints in coastal plain sand derived soil of southeastern Nigeria, for optimization of
maize (Zea mays L.) yields. Dry
matter yields, plant concentrations, plant uptake, and maize grain
yields were used to evaluate the effects of Cu and Zn levels. In both the
greenhouse and field experiments, hydrated Cu and Zn sulphate fertilizers were
applied to the soils in separate experiments at seven levels (0, 2, 4, 6, 8, 10
and 12 kg·ha-1) for Cu and Zn respectively. The recommended N, P,
and K at rates of 120, 60, 30 kg·ha-1, respectively, were
also used as basal application. The results showed the status of available Cu
and Zn by 0.1 N HCl was found to be low in the soil. The application of Cu and
Zn into the soils significantly (P < 0.05) increased maize dry matter
production, concentration, uptake and grain yields. The estimated optimum rates
for Cu and Zn under greenhouse environments were established at 10 kg·Cu·ha-1 and 8 kg·Zn·ha-1, respectively. Maximum uptake and grain yields in
maize were also established at 10 kg·Cu·ha-1 and 8 kg·Zn·ha-1,
respectively. However, maize response curve showed that for optimum grain
yield, concentration for Cu was determined to be 10 mg·kg-1, while
for Zn it was 8 mg·kg-1. The current study showed that though the
soils have a severe Cu and Zn deficiency, which could be due to their strong
sorption capacity and nutrients mining due to intensive and continuous cropping,
maize production can still be increased considerably in this soil and other
similar soils in the same agro-ecological zone within a coastal plain sand
derived soil by applying Cu and Zn at rates of 10 kg·Cu·ha-1 and 8
kg·Zn·ha-1, respectively.