Soil Organic Carbon Stock under Different Age Ranges of Cashew Agroecosystems in the Sudano-Sahelian Zone of Cameroon

Aw� Djongmo Victor,Zapfack Louis,Noiha Noumi Valery

doi:10.3844/ajabssp.2020.138.147

Abstract

The aim of this study was to quantify the current soil organic carbon stock under different age ranges of cashew agroecosystems in the Sudano-Sahelian zone of Cameroon in the context of greenhouse gas emissions and land degradation. It is so crucial for combating climate change and improving ecological restoration. Random field sampling was carried out on 0-10, 10-20 and 20-30 cm depths were collected in three age groups (0-10; 10-20; over 20 years old) of Cashew agroecosystems. Soil bulk density, Soil reaction (pH), moisture content, total nitrogen, C/N ratio, particle size distribution and soil organic carbon were determined using standard laboratory procedures and calculations. The results of the study did not reveal a significant difference in soil organic carbon stock across the different age groups of the cashew agroecosystems (P>0.05). The highest values of soil organic carbon stocks were observed in the 0-10 cm depth. Soils under plots with over 20 cashew agroecosystems in Benoue subdivisions recorded higher SOCS values (36.30±2.92 tC/ha). Similarly, the SOCS decreased with soil depth in all three age groups of Cashew agroecosystems. The mean SOC concentrations (%) ranged from 0.20±0.02-0.41±0.10%. Soil organic carbon stock ranged from 16.45±0.73-37.04±2.32 tC/ha depending on depth between the three age ranges of Cashew agroecosystems studied in the four subdivisions. The Cashew agroecosystems soils with high C stock are those with sandy loamy texture (25.79±2.29 tC/ha). Results showed a positive and significant (P 0.05) with % Sand, % Silt, % Clay, % Silt + Clay. The results show the potential contribution of Cashew agroecosystems to improve soil organic carbon sequestration and environmental protection. This information will be necessary for developing appropriate technological and political solutions to increase agricultural sustainability and combat environmental degradation in the Sudano-Sahelian zone of Cameroon.

Highlights

Carbon dioxide (CO2) is the main Greenhouse Gas (GHG) linked to human activities (FAO, 2017)
The bulk density varies from 0.80±0.01-1.20±0.12 g/cm3 depending on the depth between the three age ranges of Cashew agroecosystems studied in the four subdivisions
Data analysis for the textural fractions of the soils (Clay: P-value = 0.0268; Silt: Pvalue = 0.0000 and Sand: P-value = 0.0004) show that there is a variation in the textural composition of the soils at different depths between the three age groups of Cashew agroecosystems studied in the four subdivisions (Table 3)

Summary

Introduction

Carbon dioxide (CO2) is the main Greenhouse Gas (GHG) linked to human activities (FAO, 2017). Carbon is the major constituent of two greenhouse gases, CO2 and CH4, without which there could be no life on earth; its recycling influences biological productivity and the climate (Dass et al, 2018). The organic carbon stock present in natural soils presents a dynamic balance between the contributions of plant debris and animal excrement and the loss due of decomposition (Wang et al, 2020). Plants absorb carbon from CO2 in the air of photosynthesis (FAO, 2017). The plant photosynthesis consists in reducing carbon dioxide from the atmosphere by the water absorbed by the roots using solar energy captured by the leaves, in the presence of mineral salts, with the release of oxygen, in order to produce carbohydrates (Bossio et al, 2020)

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