Rotational grazing, animal manures and agro-forestry can enhance soil health which in turn can play a “crucial role” in meeting climate action targets, according to a new report published by the United Nation’s Food and Agriculture Organization (FAO).

The FAO today (Tuesday, February 14) published a report on its first Global Assessment of Soil Carbon in Grasslands, which examined the current state of grassland systems and their potential to sequester carbon in the soil.

The UN agency highlighted in the report that most of the world’s grasslands have a “positive carbon balance” which means the land is stable or well-maintained.

But it also emphasised in the report the importance of the “trade-offs between grassland services” on food security, biodiversity conservation and climate mitigation.

FAO researchers

According to the FAO, researchers found that farmers who improved “management practices in grasslands” – typically areas covered with grass especially used for animal grazing – could boost the capacity of soils as carbon sinks.

Researchers measured the baseline of stocks of soil organic carbon (SOC) – the carbon held within the soil that is measurable, expressed as a percentage by weight (gC/Kg soil) – in both semi-natural and managed grasslands and estimated their potential of SOC sequestration.

They found that the SOC content in the 0–30 cm depth layer of available grasslands increased by 0.3 per cent after 20 years where farmers employed “management practices that enhance soil organic carbon sequestration” and that 0.3 tonnes C/ha per year could be sequestered.

But the study also pointed to what it described as “the lack of incentives for farmers to improve management practices” and the current difficulty in accurately monitoring SOC stocks.

Thanawat Tiensin, director of FAO’s animal production and health division, said:

“This report provides a comprehensive analysis of the state of carbon stocks and potential offsets in grassland soils in the world. It can be also used as a baseline for future works to enhance soil carbon sequestration through sustainable grazing management.

“Assessing the current state of grassland systems and their potential to sequester carbon in the soil is key to better understand the benefits of grassland services for food security, biodiversity conservation and climate change mitigation.”

The FAO highlighted in its latest report that soils can act as both sources and sinks of carbon.

But it cautioned that many grasslands, which contain approximately 20% of the world’s SOC, have suffered “losses because of human activities” which it detailed as intensive livestock grazing, agricultural activities and other land-use activities.

It said this could be “reversed” by stimulating plant growth, capturing carbon in the soil, and protecting carbon in highly organic soils, such as semi-natural grasslands.

The FAO report also explored other potential options to offset the “increased demand for livestock products and land competition”.

It suggested these could include enhancing carbon inputs from plant roots by managing plant biomass removal from grazing or increasing forage production through improved species, irrigation and fertilisation.