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Zhang et al. Carbon Footprints 2025, 4, 36 https://dx.doi.org/10.20517/cf.2025.29 Page 9 of 17

Figure 2. An investigation of surface soil (0-5 cm) organic carbon stocks, annual carbon sequestration rates, and the correlation
between greenhouse gas emissions and livestock stocking rates. Mean ± SD (n = 3); (A) Soil organic carbon stocks (SOCS) content; (B)
ASOCS, annual sequestration of soil organic carbon stocks; HSR: High stocking rate; MSR: moderate stocking rate; LSR: low stocking
rate; Fenced: no grazing. Positive values indicate carbon sequestration and negative values indicate carbon release; (C) greenhouse
gases (GHG) change with the stocking rate increase. In analyses of significant differences, different letters (such as a, b) are used to
denote the level of significance for differences between groups. Identical letters indicate no significant difference (P > 0.05), while
different letters indicate a significant difference (P < 0.05).

3-year-old growing yak steers (175 ± 10.7 kg) [Table 2]. The GHG emissions from manure management
[25]
comprised night pens, manure heaps, dung patches, urine patches and DM combustion, and the totals were
319.16 ± 141.15, 453.33 ± 54.77, and 833.94 ± 460.70 kg CO -eq ha year for LSR, MSR, and HSR,
-1
-1
2
respectively [Table 2]. Urine patches emit N O gas, with the highest emission at a stocking rate of 1.33,
2
reaching 188.7 carbon dioxide equivalent per year. Manure Heaps CH emissions manure heaps CH
4
4
emissions were maximum when the grazing rate was 1.5, reaching 8.15 kg CO -eq ha year . Methane
-1
-1
2
emissions reached their highest point at night pens when the stocking rate was 1.6, and emissions decreased
when the stocking rate was further increased or decreased [Figure 3].
Farming inputs
Average electricity consumption and motorcycle gasoline were the farming inputs in the system and
amounted to approximately 200 kWh and 210 kg of gasoline each year, respectively [Table 1]. The
consumption of electricity and gasoline resulted in GHG emissions of 8.30 ± 3.37, 10.66 ± 2.36 and
15.40 ± 10.41 kg CO -eq ha year for LSR, MSR and HSR, respectively [Figure 4]; there was no significant
-1
-1
2
increase in GHG emissions by stocking rate. An increase in stocking rate of 1 unit increases electricity CO
2
emissions by 1.33. When the stocking rate is 1.6, the GHG emission of diesel oil for motorcycles reaches
14.69 kg CO -eq ha year and then begins to decline [Figure 3].
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-1
2
GHG balance and intensity
The GHG balances were expressed per unit area and per unit of animal LWG to calculate the GHG
intensity. At a grazing rate of 4 yak/ha, the carbon use efficiency was 11.3%. The carbon sequestration
amount was 23.2 t/ha/a, with a carbon sequestration efficiency of 2.0%. At this grazing rate, the carbon