Abstract:
Soil acidity and pollution of underground water resulting from the use of mineral fertilisers for crop production are major challenges in sub-saharan Africa. Organic fertilisers from plant sources such as moringa leaf extract and seed cake are environment friendly and have been used for vegetable production. However, little is known about the efficacy of powdered forms of Moringa Leaf Blade (MLB) and Leaf Petiole (MLP) as soil amendment for amaranth and okra production. Hence, the effectiveness of powdered MLB and MLP on growth and yield of amaranth and okra were evaluated.
An incubation experiment involving MLB (2.8% N), MLP (2.1% N), “Sunshine” Organic Fertiliser - SOF (1.4% N) and NPK 20:10:10 each at 100 kg N/ha as well as control (No fertiliser amendment) was conducted using 50 g soil weighed into extraction cups. The treatments were arranged in a completely randomised design with three replicates. Nitrogen release was monitored for 12 weeks at 4 weeks interval using standard procedure. On the field, the fertiliser treatments at the rate of 100 kg N/ha were evaluated for their effect on the growth and yield of amaranth and okra. Experiments were laid in randomised complete block design with three replicates. Data collected on amaranth include number of leaves and leaf area at 4 Weeks After Sowing (WAS) and on okra number of leaves and leaf area at 8 WAS. The total amaranth shoot yield (ASY) was recorded as the sum of the weight of shoot harvest at 4, 8 and 12 WAS, while total okra pod yield (OPY) was recorded as the sum of the weight of fruits harvested at five days intervals over 30 days. Data were analysed using descriptive statistics, linear correlation and ANOVA at 5 % probability level.
Nitrogen (g/kg) release differed significantly among the fertiliser sources and was in the order; control (0.5±0.01) < SOF (1.3±0.05) < MLP (1.4±0.06) < MLB (1.7±0.01) < NPK (5.1±0.06). Number of leaves and leaf area of amaranth ranged from 8.9±0.3 (control) to 14.9±0.7 (MLB) and 14.9±0.1 (control) to 53.4±2.0 cm2 (MLB), respectively. For okra, number of leaves and leaf area ranged from 20.8±0.2(control) to 37.8±0.5 (MLB) and 338.7±17.0 (control) to 657.9±21.2 cm2 (MLB). The ASY from plots treated with MLB (9.9±0.2 t/ha) and NPK (9.2±0.3 t/ha) were similar and significantly (p<0.05) higher than MLP (7.8±0.1 t/ha), SOF (6.6±0.2 t/ha) and control (3.7±0.2 t/ha). Similarly,
iii
OPY from plots treated with MLB (6.0±0.3 t/ha) and NPK (5.9±0.2 t/ha) were comparable and significantly (p<0.05) higher than MLP (5.1±0.2 t/ha), SOF (4.5±0.1 t/ha) and control (2.6±0.1 t/ha). Nitrogen release was significantly (p<0.05) and positively correlated with ASY (r = 0.58) and OPY (r = 0.63).
Moringa leaf blade powder at the rate of 100 kg N/ha improved growth and yield of amaranth and okra. Hence, it could be used as an alternative soil amendment to NPK fertiliser in amaranth and okra production.
