ABSTRACT
This study was carried out both in the screen house and in the field to determine the influence of some effluents on Soil nutrient, microbial composition, nutrient uptake and the early growth of rubber seedlings (Hevea brasiliensis). The use of these effluents as soil amendments will help in reducing the cost of inorganic fertilizer and the problem of disposal of effluent.
The study was conducted at Rubber Research Institute of Nigeria (RRIN) Iyanomo, Benin City, in Edo state. In the screen house experiment, four effluents were used; Abattoir (ABAE), Cassava mill (CASME), Rubber (RUBE) and Palm oil mill effluents (POME). Each effluent had five levels (0, 100, 200, 300 and 400 ml/kg) that were laid out in a Completely Randomized Design (CRD). The field experiment was a 2 x 4 factorial and a control fitted into Randomized Complete Block Design (RCBD). Two of the effluents (ABAE and CASME) used in the field were selected based on the performance of rubber seedlings grown on them in the screen house.
The results of the study show that Palm oil mill and Cassava mill effluents were strongly acidic (4.27 and (4.08) while Rubber and Abattoir effluents were moderately acidic (5.09 and 5.96).The soil pH, C, N, Exchangeable bases, Available P, ECEC, Zn, Fe, Mn, Cu, Ni were not significantly influenced by the effluents in screen house. In the field and residual trials, the effluents ABAE and CASME had positive effects on soil pH, C, exchangeable bases, EA, ECEC %BS. In the screen house, field and residual trials, the applied effluents increased nutrients uptake and the population of microorganisms. The prominent bacteria species identified were Bacillus subtilis and Staphylococcus aureues while prominent identified fungi species in the treated soil were Aspergillus niger, mucor sp and Penicillium sp. Saccharomyces cerevisea was found only in soils where CASME was applied. The prominent actinomycete identified was A. meyeri and was found only in ABAE and CASME. The plant height, stem girth, numbers of leaves and leaf area were enhanced by the effluents in the screen house, field and in the residual application. The highest height of 75.78 cm was recorded in soil treated with ABAE at 100 ml/kg in screen house. While in field and the residual trials, CASME at 200 l/ha treated soil had the highest height (109.06 and 56.70 cm) of rubber seedlings respectively. The highest stem girths of (10.97 and 5.58cm were recorded in plot treated with CASME 200 l/ha. The highest leaf area (44.20cm2) in screen house was recorded in soil treated with RUBE at 300 ml/kg. In field, the highest leaf area (52.95cm2) was recorded in soil treated with CASME at 200 l/ha and the highest leaf area (18.21cm2) in the residual trial was recorded in soil treated with CASME at 200 ml/kg. The soil treated with POME 300 ml/kg in screen house had the highest number of leaves (11.67). The use of abattoir and cassava mill effluents showed better improvement than the untreated plots. Therefore, their use as soil treatments is recommended for reducing the cost of inorganic fertilizer and the problem of disposal.
