Carbon stock in the solum of some coarse-textured soils under secondary forest, grassland fallow, and bare footpath in the derived savanna of south-eastern Nigeria

Abstract

Quantitative data on carbon stock (C stock) in and beyond the topsoil (0–30 cm) under natural terrestrial ecosystems in West African savanna could provide information about their relative potential, and management options, for C sequestration, but these data are still scanty in the region. In selected locations (Nsukka, Obimo, and Ibagwa-aka) in the derived savanna zone of south-eastern Nigeria, secondary forest (SFT), grassland fallow (GLF), and bare footpath (BFP) were sampled from the topsoils (0–30 cm) and subsoils (30–60 cm) in triplicate. The soils are generally sandy, with low (1.4–13.8%) mean silt content. Mean bulk density ranged from 1.30 to 1.83 Mg/m3. The soils were acidic (pHwater 4.0–4.8) and low in organic C (0.10–1.14%). There was a consistent trend in C stock (SFT > GLF > BFP) in the topsoil, whereas only higher values in SFT than BFP were consistent in the subsoil. In both soil layers, the scale of the differences among the land-cover types was location-specific. Values of C stock were higher in the topsoil than subsoil, except for GLF and BFP at Obimo due to recent bush burning. Irrespective of location, the mean topsoil–subsoil values under SFT, GLF, and BFP were 45.7–30.6, 27.7–25.8, and 19.0–18.8 Mg/ha, respectively. Soil structural stability, indexed as the ratio of organic matter to silt + clay, explained roughly 61 and 89% of the variability in C stock of topsoils and subsoils, respectively. These results should benefit the planning of C sequestration projects in savanna agroecosystems of West Africa.

Amelioration of a degraded ultisol with hardwood biochar: Effects on soil physico-chemical properties and yield of cucumber (Cucumis sativus L)

“…Soils of Southeastern Nigeria are poor in their native availability of nutrients (Mbagwu, 1989), low in organic matter content (usually <1%) and, hence are structurally degraded (Obalum et al, 2012). Soil fertility depletion in small holder farm is the fundamental cause of declining per capita food production (Sanchez et al, 1996).…”

Overlooked Influence of Indian Hemp (Cannabis sativa) Cultivation on Soil Physicochemical Fertility of Humid Tropical Agroecosystems: Upland Soils

“…In many of these industrialized nations, the roots, stems, leaves, flowers and the seeds of licit are Cannabis competitively used for recreational, medicinal and industrial purposes (Ester 2020). In tropical agro-ecosystems, vegetation directly influences soil physical and chemical properties (Watanabe et al 2010, Obalum et al 2012, 2013a, Uzoh et al 2020and Oguike et al 2022. Vegetation could facilitate nutrient cycling by extracting nutrients from lower soil horizons and redistributing them to the topsoil through leaf falls and residue decomposition.…”

Erodibility of soils of varying land utilization types and lithologic materials in central southeastern Nigeria

“…The differences in organic carbon content may be linked to the heterogeneity of land use pattern and management practices. Soil organic carbon has been reported to decrease with vegetation density among land use types (Obalum et al, 2012). The low values in the cultivated land could be due to agricultural practices that favour rapid decomposition.…”