Table 1 Mitigation management practices and explanation

From: Sound management may sequester methane in grazed rangeland ecosystems

Management

Detailed description and explanation of the management practices

1. Rangeland improvement

The focus of these measures is on restoration of degraded rangelands and recovery of rangeland ecosystem service functions.

(a) Reseeding

Reseeding legumes by no-tillage techniques to biologically fix nitrogen reduces requirements for nitrogen fertilizer use. The lack of disturbance can increase the rate of oxidation of CH4 from the atmosphere.

(b) Irrigation

Irrigation experiments added 20% of annual average precipitation. Higher moisture content in soils can lead to anaerobic conditions and increase CH4 emission. Irrigation is below threshold value of CH4 emission in arid and semiarid rangeland.

(c) Fertilization

7500 kg/ha organic fertilizer (N + P2O5 + K2O more than 5.2%, sheep dung fermented under aerobic conditions) were applied to the rangeland before forage germination in spring.

(d) Grazing prohibition

Rangeland is not grazed throughout the whole year.

(e) Control area*

Rangeland is close to households and forage is harvested for feeding livestock.

2. Rangeland utilization

The focus of these measures is on appropriate stocking rates by ascertaining carrying capacity, calculated on the basis of rangeland species composition, biomass and ground cover, to balance livestock and rangeland resources during the grazing season.

(a) Rest from grazing

Rangeland is not grazed during early spring or germination.

(b) Light grazing

Forage utilization is 24–30%.

(c) Moderate grazing

Forage utilization is 40–44%.

(d) Heavy grazing*

Forage utilization is 65–70%.

3. Livestock production

The focus of the management is on optimizing the production system to improve livestock and rangeland efficiency and reduce CH4 output per unit of livestock product.

(a) Intensive management

Management attempts to increase production or utilization per unit area or production per livestock through a relative increase in forage utilization, labor, and/or capital. Management includes change of production and management strategy (e.g., grazing in summer and indoor feeding in winter), balanced nutrition through strategic supplementation, forage processing, adjustments in dietary structure (e.g., adjust proportion of concentrate and roughage in the diets), applying feed additive and improved feeding techniques.

(b) Extensive management*

The traditional livestock management system utilizes relatively large land areas per animal and a relatively low level of labor, and/or capital. The typical model involves free grazing of livestock on rangeland throughout the whole year. Natural hay is used as feed supplement during periods of severe cold and forage shortage in winter-spring.

  1. The three stocking rates (high, moderate and light) were calculated based on the percentage of forage utilization. It was assumed that CH4 mitigation management practices are adapted at a linear rate over time. The stocking rate for all types of livestock is standardized to the sheep unit (SU, one 50 kg adult female sheep with one suckled lamb) per ha, where one cattle is 6.8 SU and one goat is 0.87 SU.
  2. *Control area (1e), heavy grazing (2d) and extensive management (3b) are used as the control for comparison with management 1a–1d, 2a–2c and 3a, respectively and are not considered as mitigation management practices.
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