Soil organic carbon sequestration potentials in aggregate fractions of cultivated and uncultivated soils of southeastern nigeria

Project Abstract

<p> A study was carried out on soils sampled at 0-10, 10-20, and 20-30 cm depths from both<br>cultivated and uncultivated soils at four different locations (Awgu, Okigwe, Nsukka I, and<br>Nsukka II), to evaluate the potentials of various aggregate size fractions of varying soil textures<br>and depths to sequester carbon under different land uses. A 4 x 2 x 3 factorial experiment was<br>conducted in a completely randomized design (CRD). Factor A was location at four levels, while<br>factor B (land use) had two levels. Factor C (soil depth) comprised of three levels. Results<br>showed that in both land uses, soil texture varied with depth in each location and included clay,<br>loam, clay loam, sandy loam and sandy clay loam. Generally, all the soil properties varied with<br>soil depth across the locations and land uses. Land use significantly (P = 0.05) affected pH in<br>KCl, Ca2+, Al3+, CEC, 0.50-1.00 mm water stable aggregates (WSA), total soil nitrogen (TSN) in<br>1.00-2.00 mm WSA, and soil organic carbon (SOC) in 1.00-2.00 mm and<br>clay &gt; sandy loam &gt; loam &gt; sandy clay loam. In all, SOC pool was most secluded at 10-20 cm<br>depth, and least at 20-30 cm depth. Whereas SOC pool significantly correlated with dispersion<br>ratio (DR), aggregated silt and clay (ASC), water dispersible clay (WDC), microporosity (Pmi),<br>0.50-1.00 mm WSA, mean weight diameter (MWD), soil pH, K+, and C/N ratio in cultivated<br>soils; it correlated significantly with ASC, Na+, and CEC in uncultivated soils. Apart from Pmi,<br>whose variability was largely due to the effect of SOC that significantly predicted up to 76 %,<br>SOC significantly accounted between 34 % and 54 % of the variability in MWD, WDC, and<br>WSA classes of &gt; 2.00 mm, 1.00-2.00 mm and 1.00-0.50 mm of the cultivated soils. <br></p>

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