Increased environmental pollution has necessitated the need for eco-friendly clean-up strategies. Filamentous fungal species from gold and gemstone mine site soils were isolated, identified and assessed for their tolerance to varied heavy metal concentrations of cadmium (Cd), copper (Cu), lead (Pb), arsenic (As) and iron (Fe). The identities of the fungal strains were determined based on the internal transcribed spacer 1 and 2 (ITS 1 and ITS 2) regions. Mycelia growth of the fungal strains were subjected to a range of (0–100 Cd), (0–1000 Cu), (0–400 Pb), (0–500 As) and (0–800 Fe) concentrations (mgkg−1) incorporated into malt extract agar (MEA) in triplicates. Fungal radial growths were recorded every three days over a 13-days’ incubation period. Fungal strains were identified as Fomitopsis meliae, Trichoderma ghanense and Rhizopus microsporus. All test fungal exhibited tolerance to Cu, Pb, and Fe at all test concentrations (400–1000 mgkg−1), not differing significantly (p > 0.05) from the controls and with tolerance index >1. T. ghanense and R. microsporus demonstrated exceptional capacity for Cd and As concentrations, while showing no significant (p > 0.05) difference compared to the controls and with a tolerance index >1 at 25 mgkg−1 Cd and 125 mgkg−1 As. Remarkably, these fungal strains showed tolerance to metal concentrations exceeding globally permissible limits for contaminated soils. It is envisaged that this metal tolerance trait exhibited by these fungal strains may indicate their potentials as effective agents for bioremediative clean-up of heavy metal polluted environments.

Cornstover, garbage compost, and cowdung were added to an Alfisol (Iwo series) at the rates of 0, 23, 69, and 115 Mg ha -1 and incubated for 4 weeks in the greenhouse prior to sowing cowpea [Vigna unguiculata (L.) var. Ife Brown]. Two successive plantings were made per pot. Harvesting of the plants was at onset of flowering, 42 days after planting. Nitrogen (N) fixed was assessed using the N 2 difference method. Soil reaction (pH), organic carbon (C), and tissue N contents were increased by all the organic amendments. At both harvests, dry matter yields were significantly enhanced by garbage compost and cowdung. While garbage compost and cowdung increased the amounts of N 2 fixed, the efficiency of N 2 fixation was higher in the cornstover treatments. The cornstover additions also significantly increased nodule size and number. These results suggest that organic amendments would benefit N 2 fixation especially in soils low in indigenous organic matter. The beneficial effects were in the order: cowdung > garbage compost > cornstover. To enhance N 2 fixation in cowpea, a rate of 23 Mg ha -1 of these organic amendments is suggested. 2455

The effects of amending soil with organic (poultry manure) and inorganic fertilizer on yield and chlorophyll content of maize (Zea mays L.) and sorghum (Sorghum bicolour (L.) Moench) was carried out at the Teaching and Research (T&R) Farm of the Obafemi Awolowo University, (O.A.U.) Ile-Ife, Nigeria. The experiment was a randomised complete block design (RCBD), laid out in a split-plot arrangement in the second cropping season of year 2001 and 2002. There were four sources of fertilizer for soil amendment: inorganic fertilizer (IF), mixture of inorganic fertilizer and poultry manure (IFPM), poultry manure (PM) and control (C) (no fertilizer or manure treatment). Each fertilizer source supplied 54 kg N plus 25 kg P 2 O 5 and 25 kg K 2 O 5 /ha. There were significant variability and diversity observed on the two crops due to treatments. Grain yield was highest in sorghum (3.55 kg/ha) and maize (2.89 kg/ha) under IFPM followed by IF treatment for maize (2.33 kg/ha) and PM treatment for sorghum ((3.37 kg/ha). Sorghum and maize had the highest dry matter of 72.3 g/plant and 71.0 g/plant under IFPM at harvest. The effects of PM on the dry matter of sorghum (68.1 g/plant) and maize (61.7 g/plant) were not significantly different (p = 0.05) from that of IF (sorghum 66.1 g/plant, maize 58.7 g/plant). Sorghum also had the highest leaf area (LA) (2752.9 cm 2 /plant) and total chlorophyll content of 3.28 mg/g under PM while maize on the other hand had the highest LA (1969.5 cm 2 /plant) and total chlorophyll content of 2.63 mg/g under IFPM. In both maize and sorghum, the lowest chlorophyll content occurred in control plot. Drought tolerance measured as percentage chlorophyll stability index (CSI%) was highest under control plots in both crops.

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The study on agronomic efficiency of Sokoto Rock Phosphate (SRP) and water Soluble Single Super Phosphate (SSP) as a phosphorus (P) fertilizer sources for maize (Zea mays L. Van TZSRY) was carried out on Iwo Soil Series (Oxic Tropudalf) in the field. The initial (1989) and residual (1990) effects of the two sources of P were assessed. The treatment consist of the control. Two P sources applied at the rates of 25, 50, 100, and 200 kg ha -1 and their mixtures in equal ratios at the rates of 50 and 100 P ha -1 . The available P was slowly released from SRP in the first year of trial. In the second year however, the SRP supplied significantly higher P than the SSP. The effectiveness of the different rates of SRP in increasing maize grain yields in the initial experiment followed the order of SRP 25 > SRP 50 > SRP 100 > SRP 200 while the residual effect after one year on yield was as follows: 1340 AKANDE ET AL. optimum grain yields of 5.9 and 5.1 tonnes ha -1 were obtained with SSP at the rate of 50 and 100kg ha -1 in the initial (1989) and residual (1990), respectively. The optimum grain yield could not be ascertained in the initial (1989) experiment for SRP because the yield declined as the rates of SRP increased. But in the residual (1990) effects, it was 4.9 tonnes ha -1 at the rate of 50kg ha -1 . The relative agronomic efficiency values ranged from -500% to 0% and 150% to 100% in the initial and residual effects, respectively. This indicates that Sokoto Rock Phosphate was more effective in supplying P for maize growth in the second than the first year of the experiment.