Effects of grassland conversion to croplands on soil organic carbon in the temperate Inner Mongolia

• Published in: Journal of environmental management 2008-02, Vol.86 (3), p.529-534
• Main Authors: Wang, Zhi-Ping, Han, Xing-Guo, Li, Ling-Hao
• Format: Article
• Language: English
• Subjects: agricultural land; Agriculture; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Applied ecology; arid lands; Biological and medical sciences; Carbon; Carbon - analysis; Chemistry; China; Climate; Conservation, protection and management of environment and wildlife; crop production; Crops; Crops, Agricultural - growth & development; Crops, Agricultural - metabolism; deserts; Environmental Monitoring; Farmland; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; General aspects; Generalities. Agricultural and farming systems. Agricultural development; grassland soils; Grasslands; land management; Land use; land use change; Meadow; Mongolia; Nitrogen; Organic chemicals; Poaceae - growth & development; Poaceae - metabolism; Semi-arid region; Soil - analysis; soil depth; soil horizons; soil organic carbon; Soil organic matter; Soils; temperate soils; temperate zones
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2006.12.004

This study investigated the effects of grassland conversion to croplands on soil organic carbon (SOC) in a typical grassland-dominated basin of the Inner Mongolia using direct field samplings. The results indicated that SOC contents decreased usually with increasing soil depth, with significant differences between the upper horizons (0–30 cm) and the underlying horizons (30–100 cm). Also, SOC densities decreased with an increase in the depth of soils. Average SOC densities in the upper horizons were 2.6–3.7 and 6.0–8.3 kg C m −2 for desert grassland–cropland sites (sites 1 and 2) and meadow–cropland sites (sites 3 and 4), respectively, with significant differences between grasslands and croplands ( P < 0.05 ). However, the SOC densities in the underlying horizons did not significantly differ between the land uses. The SOC densities up to 100 cm depth were much higher in the meadow–cropland sites than in the desert grassland–cropland sites, reaching approximately 16 and 6 kg C m −2, respectively. The SOC: total nitrogen (TN) ratios were approximately 10, with no significant difference among the soil horizons of grasslands and croplands. The conversion of grasslands to croplands induced a slight loss of SOC, with a range of from −4% to 22% for the 0–100 cm soil depth over about a 35-year period, in the temperate Inner Mongolia.