Land use influences microbial biomass carbon, organic carbon and nitrogen stock in a tropical acric luvisols of Southwestern Nigeria

Segun Oluwatomiwa Oladele,Adebayo Jonathan Adeyemo

doi:10.21472/bjbs.030617

Abstract

A study was conducted to determine the effect of different land use on microbial biomass carbon, organic carbon and nitrogen stock on a tropical acric luvisols at Ibadan, Oyo State, Southwestern Nigeria. Soil samples were collected in 2014 using a quadrant approach across ten plots at the surface (0-15 cm) and sub-surface (16-30 cm) depths in four different land use systems of (i) 8-year old citrus, (ii) 8 year old cacao, (iii) 8 year oil palm and (iv) a fallow land of over 25 years. Significant differences in soil physical and chemical properties, microbial biomass carbon, carbon and nitrogen stock in different land use types at two depths (0-15 and 15-30 cm) were observed on soil properties important for sustainable crop production. Fallow land use, oil palm plantation and cocoa plantation were characterized by higher carbon and nitrogen stock, microbial biomass carbon, total nitrogen, organic carbon, available phosphorus, marginally low exchangeable bases except for Ca and Mg with relatively higher values and marginal C/N ratio. These land use also had lower bulk density, high total porosity, high moisture content and optimum soil temperature level. These results suggest that incorporation of optimum fallow cycle with appropriate land use in combination with soil enriching cover and tree crops in the study area will increase carbon and nitrogen stock while imitating a forest ecosystem condition which would help restore soil fertility in degraded lands while reducing greenhouse gas fluxes.

Highlights

Soils are important sink of active carbon and play a major role in carbon sequestration, carbon and nitrogen cycle (Verena et al, 2010)
Land use types based on the cropping system showed that bulk density was significantly (P < 0.05) reduced and changes noticed when compared with other land use types under the fallow land and citrus plantation treatment with values of (1.26 g/cm3 and 1.27 g/cm3) recorded (Table 1), values recorded in the other land use type were still below the ideal recommended bulk density weight of tropical soils according to Brady and Weil (2002)
Total porosity was significantly different (P < 0.05) amongst the land use type, total porosity in soil analyzed from citrus plantation and fallow land were higher with values ranging from 52.05%-52.39% when compared with other land use types (Table 1)

Summary

Introduction

Soils are important sink of active carbon and play a major role in carbon sequestration, carbon and nitrogen cycle (Verena et al, 2010). Soil can be an important source of atmospheric CO2 storage depending on land use, vegetation, soil cover and management practices (Lal, 2005). Anthropogenic induced influence on loss of soil organic matter from cultivated soil with profound over bearing effect on chemical, physical, and biological soil characteristics is widely used as an indicator of soil degradation and quality. Forest soils are one of the major sequesters of carbon on earth due to their high organic matter status (Dixon et al, 1994). The tree-crop agroforestry systems proffers an excellent opportunity in conserving soil organic matter while maintaining permanent soil cover, which.

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