Background: Utilization of palm mill liquid effluent and bat guano as organic fertilizer was initiated in year 2019 and 2020. The palm oil mill effluent and bat guano were used to produce compost and was tested on maize and soil properties in Asaba, Delta State. Methods: The compost was applied at 0, 2.5, 5.0, 7.5 and 10 ton/ha and replicated four times in randomized complete block design for two years. Plant height, leaf area, stem girth were assessed at maturity whereas yield parameters and soil chemical properties measured at harvest. Data collected were analysed with analysis of variance and means separated with Duncan’s multiple range test at 5% level of probability. Result: Compost significantly increased maize yields and soil properties. The 10 t/ha gave the highest dry matter yield (22.1±2.71 and 36.2±7.47 t/ha), weight of 1000 grains (324±41.0 and 364±63.3) and grain yield (5.2±1.04 and 6.4±1.61 t/ha) in both years, respectively. It also, had the highest soil pH value, organic carbon, total nitrogen and available phosphorus. The palm mill liquid effluent and bat guano mixtures have the potentials to be used as organic fertilizer for maize production.

Background: Limited information on impact of oil exploration on soil fertility in Nigeria is hindering the efforts toward soil improvement. Hence, the impact of oil exploration on soil fertility in four local government areas (LGA), Delta State, Nigeria was evaluated in 2020. Methods: Two LGAs in oil producing (Ukwani, Ndokwa) and non oil producing (Aniocha South, Ika South) and three communities in each LGA and one crop largely cultivated was purposely chosen. Soil samples were taken from 0-30 cm depth at 10 meters intervals along transverses cut at 100 m apart. The samples were air-dried at room temperature, crushed and made to pass 2 mm sieve. Soil pH, organic matter, nitrogen, phosphorus, calcium, magnesium, potassium and sodium were measured. Data were statistical analyzed and least significance difference at α0.05 was used to separate means while Parker’s nutrient index was used to rate the fertility. Result: Ukwani soil was strongly acidity (5.30), Ndokwa was moderately acidity (5.83) while Ika (6.61) and Aniocha (6.27) were slightly acidity. Organic matter (2.54 and 2.48%) and phosphorus (16.98 and 14.51 mg/kg) were medium in Ika and Aniocha whereas, both were low in Ukwani (1.49%, 10.14 mg/kg) and Ndokwa (1.74%, 12.52 mg/kg), respectively. Nitrogen was high in Ika (0.27%) and Aniocha (0.42%), medium in Ndokwa (0.18%) and low in Ukwani (0.15%). Potassium and sodium were high in Ika, Aniocha and Ukwani but medium in Ndokwa. Calcium was high in Ika, medium in Aniocha but low in Ndokwa and Ukwani. Magnesium was high in Ika, Aniocha and Ndokwa but was medium in Ukwani.