This study presents an evaluation of soil organic carbon (SOC) and stock (SOC_stock) for the whole rooting depth (60 cm), spaced 55 months in two adjacent olive orchards with similar conditions but different tree densities: (i) intensive, planted in 1996 at 310 tree ha⁻¹; (ii) superintensive, planted in 2000 at 1850 tree ha⁻¹. This was carried out to test the hypothesis that olive orchards at different plant densities will have different rates of accumulation of SOC in the whole soil rooting depth. SOC increased significantly in the superintensive orchard during the 55-month period, from 1.1 to 1.6% in the lane area, and from 1.2 to 1.7% in the tree area (average 0–60 cm), with a significant increase in SOC_stock from 4.7 to 6.1 kg m⁻². In the intensive orchard, there was not a significant increase in SOC_stock in 0–60 cm, average of 4.06 and 4.16 kg m⁻² in 2013 and 2018, respectively. Results indicate a potential for a significant increase in SOC and SOC_stock in olive orchards at higher tree densities when combined with temporary cover crops and mulch of chopped pruning residues. The increase is associated with an increase in SOC, mainly at a 0–15 cm depth. Results also point to the need for improve our monitoring capabilities to detect moderate increases in SOC.

The objective of this study was to determine the soil organic carbon stock (T-SOC stock) in different mountain soils in the Babia Góra National Park (BNP). Environmental factors, such as the topography, parent material, and vegetation, were examined for their effect on carbon stock. Fifty-nine study plots in different BNP locations with diverse vegetation were selected for the study. In each study plot, organic carbon stock was calculated, and its relationships with different site factors were determined. The results reveal that the SOC stocks in the mountain soils of the BNP are characterized by high variability (from 50.10 to 905.20 t ha ${}^{-1}$ ). The general linear model (GLM) analysis indicates that the soil type is an important factor of soil organic carbon stock. Topographical factors influence soil conditions and vegetation, which results in a diversity in carbon accumulation in different mountain soils in the BNP. The highest carbon stock was recorded in histosols (>550 t C ha ${}^{-1}$ ), which are located in the lower part of the BNP in the valleys and flat mountain areas.

Soil organic carbon (SOC) is an important indicator of soil quality; an elevated percentage of SOC indicates very high-quality soil, physically as well as chemically. As such, the principal objective of the present study was to determine the concentration of SOC at different depths, as well as its accumulation through the entire soil profile. The Carrizal-Chone system (SCCH) area was stratified by agricultural use. Sixty-three soil samples were taken from different depths of up to a maximum of 150 cm. The physical and chemical properties of the soil were determined. SOC was determined by the Walkley and Black method. The following results are highlighted: (1) 21 different varieties of soil management were identified; (2) the largest area was livestock grazing land, which had the greatest concentration of SOC; (3) the type of soil with the greatest SOC sequestration capacity was silty clay loam; (4) the area cultivated with corn presented the highest accumulation of total carbon; and (5) the highest concentration of SOC was found in the top 40 cm, with a tendency to decrease with depth. It is concluded that soil management influences the concentration and accumulation of SOC in the topsoil layers and the entire soil profile.

Soil organic carbon (SOC) plays a crucial role in soil quality and nutrient availability. Agricultural practices, such as tillage and crop rotations, can affect SOC levels. Pitahaya cultivation, a growing crop in dry tropical environments regions may affect soil quality due to weed management. This study aims to assess the relationship between alternative crop management and pitahaya species on SOC sequestration. Two plots, each for yellow (Selenicereus megalanthus) and red (Hylocereus Undatus) pitahaya, were established. Rice husks were used as a natural mulch to prevent weed growth as a new control alternative. Soil sampling was conducted at different depths (0-5, 5-10, 10-20, and 20-30 cm) and locations (below plant vs row) within the pitahaya plots. The study found at the 0-5 cm section presents the highest concentration of organic carbon at 2.01%, 1.77%, and 1.97% below plant in red, yellow, and row in yellow plantation respectively. In comparison with 1.26% in row red plantation, they are significant differences. The analysis of carbon accumulation showed variability in each of the locations from 0-30 cm. Without significant differences with 50.34, 49.40, and 47.95 (t ha-1) below the yellow plant, row, and below red plant respectively. In the whole soil profile with 38,10 t ha-1 the row of the red plant is significantly different. Likewise, the age of the plantation or crop plays another important role in soil organic carbon sequestration. Despite having the same management, soil type, climate, and irrigation, the significant effect in this study shows that the different age of the plantations (2 years) marks a significant difference between the two plantations. The roots of the older plantation extend their roots more horizontally and achieve more organic carbon sequestration in the rows compared to the younger plantation.