Variation in Total Soil Organic Carbon Stocks in Relation to Some Land Use Systems in the Bamenda Highlands, Cameroon

Christian Tegha Kum,Cornelius Tsamo,Aaron Suh Tening,Martin Ngwabie

doi:10.4236/gep.2021.99009

Abstract

Climate change and food security are among the pressing challenges facing humanity in the 21st century. Soil organic carbon (SOC) stocks, total nitrogen (TN), texture, and bulk density (BD) are important soil properties, which control climate change. Three land use systems (smallholder farmlands, grazing lands, and forest lands) that coexist in the Bamenda Highlands (BH) influence ecosystem services and induce soil degradation with the loss of SOC. The objective of this study was to evaluate the variation of SOC and some soil physicochemical properties as affected by the three land use systems (LUS). A total of 21 composite soil samples collected from 7 microclimatic zones of BH following “S” shape plots to the depth of 0 - 30 cm, were analysed for moisture content (MC), SOC, TN, BD, available phosphorus (Av.P), pH and texture. The results revealed that grazing land had the lowest mean sand content (40.79 ± 4.07). Mean MC, TN and SOC (%) content were significantly higher (p in forest land than those in the grazing land and smallholder farmlands. Conversely, BD and Av.P were significantly higher (p in smallholder farmlands than grazing and forest lands probably due to different litter accumulation and agricultural practices. Moisture content and TN revealed positive significant correlations (p 0.05) with SOC, while BD and Av.P revealed negative significant correlations (p 0.05). Mean SOC density in smallholder farmlands (132.91 ± 9.48 tC/ha) was the lowest among the three land use types. Losses in CO2 equivalence, as a result of land use change from forest lands to smallholder farmlands were 137.33 t/ha while that from grazing lands to smallholder farmlands were 109.13 t/ha. Total organic carbon (TOC) stocks differed significantly (p 0.05) from smallholder farmlands (10.73 Mt) to forest lands (91.13 Mt). A sustainable farming technique that enhances SOC sequestration and minimizes soil CO2 emissions is therefore recommended to replace tillage ridges formation commonly practiced by smallholder farmers.

Highlights

The two most pressing and interlinked challenges facing human and environmental sustainability in this 21st century are climate change and food security (Godfray et al, 2011)
The land use map derived from the Landsat-4 data is shown on Figure 2 and the land surface areas of smallholder farmlands, grazing lands, and forest lands are shown on Table 1
Soil moisture content (MC), bulk density (BD), and texture play an important role in Soil organic carbon (SOC) formation and transformation during land-use and/or land-cover changes

Summary

Introduction

The two most pressing and interlinked challenges facing human and environmental sustainability in this 21st century are climate change and food security (Godfray et al, 2011). According to IPCC (2001), the accumulation of Carbon dioxide (CO2) in the atmosphere is the leading factor attributed to be the basis of climate change. Efforts to achieve food security through intensification of agricultural activities contribute heavily to the accumulation of CO2 in the atmosphere leading to the global climate change challenge. Land use change may induce changes in the biological, physical, chemical, and hydrological properties of soils. Yao et al (2010) stated that soils can differ in physical properties based on land use types. These physical properties are crucial to root growth, infiltration, water and nutrient holding capacity (Zhang & Shangguan, 2016)

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