Sustainable Practices for Restoring Cocoa Farm land in Gold Mining-Damaged Agricultural Lands in South West Nigeria
Description
Research Hypothesis The hypothesis of this study is that biochar and inorganic amendments significantly improve soil health, cocoa growth, and biodiversity in gold mining-impacted agricultural lands compared to untreated control plots. Description of the Data The dataset includes field data collected over 12 months from two gold mining-impacted agricultural sites (Aba Ooni and Aye Isale) in Osun State, Nigeria. The study employed a randomized complete block design with three treatments: biochar, inorganic amendments (NPK and lime), and a control. The dataset comprises: 1. Soil Parameters: Soil pH, organic matter content, macronutrients (N, P, K, Ca, Mg), and heavy metal concentrations (Hg, Pb, Cd). 2. Cocoa Growth Parameters: Plant height, stem diameter, leaf area index, and plant vigor scores. 3. Biodiversity Metrics: Plant and pollinator species counts and Shannon-Wiener Diversity Index. Key Findings 1. Soil Health Improvement: o Biochar significantly improved soil pH (6.2 ± 0.2) and organic matter (2.8 ± 0.1%) compared to control and inorganic amendments. o Biochar reduced heavy metal concentrations (e.g., Hg: 0.12 ± 0.01 mg/kg vs. 0.65 ± 0.02 mg/kg in control). o Inorganic amendments were effective but less impactful than biochar. 2. Cocoa Growth Enhancement: o Biochar-treated cocoa plants showed the greatest height (78 ± 4.2 cm) and stem diameter (4.0 ± 0.3 cm). o Leaf area index and plant vigor scores were highest in biochar plots, indicating enhanced photosynthesis and overall health. 3. Biodiversity Improvements: o Biochar-treated plots had the highest biodiversity, with 18 ± 1.5 plant species and 9 ± 0.7 pollinator species. o The Shannon-Wiener Index was highest in biochar plots (2.5 ± 0.2), reflecting improved ecosystem stability. Data Interpretation and Usage • Soil Restoration: The data highlights biochar’s superior ability to rehabilitate degraded soils, especially in mitigating acidity and heavy metal contamination. • Cocoa Productivity: Growth metrics show that biochar improves cocoa plant development through better nutrient availability and soil structure. • Ecosystem Health: Biodiversity metrics emphasize the role of biochar in enhancing ecological balance, making it a sustainable agricultural amendment. Applications Researchers and agricultural practitioners can use this dataset to: • Develop sustainable soil restoration strategies in mining-impacted areas. • Optimize biochar and inorganic amendment applications for cocoa farming. • Assess biodiversity as an indicator of agroecosystem health. The findings affirm biochar’s effectiveness in soil remediation and agroecological restoration, supporting its adoption for sustainable agricultural practices.
Files
Steps to reproduce
The data was gathered through field experiments conducted in two gold mining-impacted agricultural sites in Osun State, Nigeria: Aba Ooni and Aye Isale. The following methods and protocols were used: 1. Experimental Design: A randomised complete block design (RCBD) with three replicates was used. Six plots per site (10 m² each) were treated with biochar, inorganic amendments, and control treatments, with 1-metre buffer zones to prevent cross-contamination. 2. Soil Amendments: Biochar was produced from rice husks and sawdust via kiln pyrolysis (400–500°C) and applied at 5 tonnes per hectare. Inorganic amendments included NPK (15:15:15) fertiliser (200 kg/ha) and lime (2 tonnes/ha). Amendments were mixed manually into the top 15 cm of soil before transplanting cocoa seedlings. 3. Cocoa Cultivation: Certified cocoa seedlings (Theobroma cacao varieties Forastero and Criollo) sourced from IITA were transplanted during the rainy season. 4. Data Collection: o Soil samples were collected quarterly and analysed for pH, organic matter (Walkley-Black method), macronutrients (N, P, K, Ca, Mg), and heavy metals (Hg, Pb, Cd) using flame photometry, spectrophotometry, and atomic absorption spectroscopy (AAS). o Cocoa growth was monitored monthly for height, stem diameter, leaf area index, and vigour scores. o Biodiversity assessments were conducted biannually using transect surveys, recording plant and pollinator species diversity. 5. Data Analysis: Statistical analysis (ANOVA, Tukey HSD, regression, PCA) was performed using SPSS software (version 24) to assess treatment effects and relationships among parameters. These methods and protocols can be reproduced for similar studies on soil restoration and agricultural productivity in degraded environments.