Grassland soil carbon and nitrogen stocks under temperate livestock grazing
2015
Cui, Junfang | Askari, Mohammad Sadegh | Holden, Nicholas M.
Sustainable grassland management is critical to many agricultural economies because of the significant proportion of agricultural commodities derived from grass-fed livestock (milk and meat). Mismanagement will result in a cycle of soil quality deterioration and reduced productivity. This study estimated carbon (C) and nitrogen (N) stocks in relation to grazing management in Ireland, with a focus on understanding the role of management intensity derived from the interaction of stocking rate, N fertiliser rate and reseeding frequency. Soil samples were taken from depths 0–10, 10–20 and 20–30cm. Soil physical properties, C and N concentrations, and microbial biomass C were measured. Significant increases in C and N concentrations were observed along the texture gradient: sandy loam<loam<sandy clay loam<clay loam<silty clay loam. However, there was little difference in C and N stock according to soil texture class. Soil with 10–20-year-old grass sward contained the lowest soil C and N content, indicating that proper reseeding is necessary to maintain soil C and N storage capacity. Increased chemical N fertiliser rate did not cause changes of soil C and N content, whereas intensified stocking rate caused great changes in soil C and N content by re-locating soil C and N at depth. Moderately intensive management was associated with significantly lower C and N stocks, and highly intensive management was associated with greater capacity of soil C and N, but no interaction between texture and management intensity was found.
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