SPATIAL STUDIES ON GINGER AND PIGEON PEA-BASED AGROFORESTRY SYSTEMS AND IMPLICATIONS FOR CARBON SEQUESTRATION AND SOIL NUTRIENT RECAPITALIZATION IN UMUDIKE, SOUTHEAST NIGERIA

Abstract

This spatial study on ginger and pigeon pea-based agroforestry systems assessed the impacts of location and agroforestry systems on soil health and carbon sequestration in southeastern Nigeria. A split-plot design experiment with four replications was employed, using location as the main plot and agroforestry production systems as subplots. Three locations (Olokoro, Western Farm NRCRI Umudike, and Eastern Farm NRCRI Umudike) and four ginger production systems—Ginger-Pigeon Pea Alley System (GPAS), Ginger-Pigeon Pea Scatter System (GPSS), Sole Ginger Unmulched (SGU), and Sole Ginger with Mulch (SGM)—were evaluated. The experiment utilized 2m x 5m plots, with ginger planted at 20cm x 20cm spacing and pigeon pea at 20cm x 40cm spacing. Ginger was introduced 2 months after the planting of pigeon pea. Results indicated significant location effects on initial soil pH, organic carbon, and nitrogen levels, with Olokoro Farm showing the highest soil organic matter (26.2 g/kg). Agroforestry systems significantly improved soil health, with GPAS and GPSS increasing soil organic matter by 15% and 12%, respectively. Carbon sequestration ranged from 14.2 t/ha (SGU) to 25.1 t/ha (GPAS). The study specifically highlighted the efficacy of the ginger-pigeon pea alley system (GPAS) and mulching in promoting soil health and enhancing carbon sequestration. Furthermore, integrating ginger and pigeon pea into alley or scatter systems enhanced ecosystem services, reduced soil erosion, and improved biodiversity.