Estimating Farm-level GHG Emissions: Part 2

In order to adopt good management strategies, farmers need to estimate the greenhouse gas emissions that are produced by their farms, says Roelof Bezuidenhout.

As described in the previous issue (FW, 14 June), Philemon Ngala, a senior scientist at the Grootfontein Agricultural Development Institute, conducted a study on a 150ha farm on the Great Fish River that produced sheep and cattle under extensive farming conditions with supplementation during the drier parts of the year.

Nearly 80% of the land consists of irrigated maize, lucerne and rye grass lands. These crops support the animal production component of the farm and generate extra income.

Ngala found that even though enteric fermentation was the main contributor to the farm’s greenhouse gas (GHG) emissions, it was second to the emissions produced by feed. This was due to a number of factors: the wide range of emission sources associated with feed emissions, such as managed soils (fertiliser application and manure deposited on pasture); transportation; energy use; landuse change; and feed material (crops, crop residues, by-products and feed supplements).