The impact of charcoal production on soil hydraulic properties, runoff response and erosion susceptibility were studied in both field and simulation experiments. Core and composite samples, from 12 randomly selected sites within the catchment of Kotokosu were taken from the 0-10 cm layer of a charcoal site soil (CSS) and adjacent field soils (AFS). These samples were used to determine saturated hydraulic conductivity (Ksat), bulk density, total porosity, soil texture and color. Infiltration, surface albedo and soil surface temperature were also measured in both CSS and AFS. Measured properties were used as entries in a rainfall runoff simulation experiment on a smooth (5 % slope) plot of 25 x 25 m grids with 10 cm resolutions. Typical rainfall intensities of the study watershed (high, moderate and low) were applied to five different combinations of Ks distributions that could be expected in this landscape. The results showed significantly (p < 0.01) higher flow characteristics of the soil under charcoal kilns (increase of 88 %). Infiltration was enhanced and runoff volume reduced significantly. The results showed runoff reduction of about 37 and 18 %, and runoff coefficient ranging from 0.47-0.75 and 0.04-0.39 or simulation based on high (200 mm h -1 ) and moderate (100 mm h -1 ) rainfall events over the CSS and AFS areas, respectively. Other potential impacts of charcoal production on watershed hydrology were described. The results presented, together with watershed measurements, when available, are expected to enhance understanding of the hydrological responses of ecosystems to indiscriminate charcoal production and related activities in this region.Index terms: hydro-physical properties, infiltration, simulated runoff, watershed hydrology.(
AbstractNutrients use efficiency of plants could be affected by the antagonistic or synergistic effects of two or more elements in the soil leading to decreased or increased yield. Field experiments were conducted in 2017 and 2018 cropping seasons at the Landmark University Teaching and Research farm, Omu-Aran, Nigeria, to determine the interaction between zinc (Zn) and phosphate (P) fertilizers on growth, yield, nutrient elements and some heavy metals composition of groundnut grown on an Alfisol. Treatments consisted of four levels of phosphorus (0, 40, 80 and 120 kg P ha-1) and three levels of zinc (0, 4 and 8 kg Zn ha-1). The experiment was laid out in a Randomized Complete Block Design (RCBD), replicated four times. The following parameters were taken: plant height, plant spread, total biomass, number of pods/plot, weight of pods/plot, number of seeds/plot, weight of seeds/plot. Laboratory analysis of some chemical constituents of groundnut seed was carried out to determine the nutrient and heavy metals composition. Results indicated that application of 8 kg Zn ha-1 and 120 kg P ha-1 had a synergistic effect on the growth parameters and antagonistic effect on the yield, yield parameters, some nutrient elements and beneficial heavy metals. Application of 8 kg Zn and 80 kg P ha-1 is therefore recommended on an Alfisol without necessarily increasing the concentration of non-beneficial heavy metals in groundnut seed.
Management of tomato early blight pathogen (Alternaria solani) has relied principally on application of synthetic fungicides. The use of biological control agents has been recognized as a viable option to synthetic chemicals in plant disease control. The present study evaluated the effects of Pseudomonas fluorescens, P. aeruginosa, P. putida, and P. cepacia on tomato early blight pathogen and investigated their efficacy on the yield components and yield of tomato plants infected with A. solani. Tomato seeds raised in the nursery beds were transplanted to the main field after three weeks. The experiment was laid in a randomized complete block. Treatment application was done by immersion of roots of threeweek-old seedlings of tomato in Pseudomonas solution prior to transplanting. The treatments consisted of plots treated with P. fluorescens, P. aeruginosa, P. putida, P. cepacia and the control. Data were collected on disease severity, plant height, stem girth, number of fruits per plant, fruit length and fruit weight. Tomato plants in the control plot had significantly (p<0.05) higher disease severity (52.0) There was no significant difference in the severities of early blight on tomato plants treated with P. fluorescens, P. putida and P. cepacia. Tomato plants treated with P. aeruginosa had significantly (p<0.05) higher height (39.0 cm) than all other treatments. There was no significance difference in the fruit weights of tomato plants treated with P. fluorescens, P. aeruginosa, P. putida, and P. cepacia. Tomato plants in the control plots had a significantly lower fruit weight (69.5 g). Findings of the present study demonstrated a promising approach of biological control of early blight pathogen with Pseudomonas species. Results of this work could be used as bedrock for formulation of an effective and eco-friendly strategy for the management of early blight disease.
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