Grazing optimizes forage production and soil GHG emissions of mixed perennial pasture in an inland arid area

Abstract

Context

In the context of global warming and increasing demands for forage production, optimizing greenhouse gas (GHG) emissions and forage production is crucial to sustainable pasture management in arid areas.

Objective

A 4-year experiment was conducted to compare the impacts of grazing versus haying on GHG emissions and forage yields in a mixed perennial pasture of alfalfa (Medicago sativa) and tall fescue (Lolium arundinaceum) on a saline cropland.

Methods

Static box method was used to measure the monthly dynamics of soil CO₂, CH₄, and N₂O fluxes. We measured the forage dry matter (DM) and crude protein (CP) yields, and soil properties, and calculated the GHG intensity (GHGI) to assess the balance between forage yields and GHG emissions.

Results

We found that grazing reduced total GHG emissions by 17.2 % compared to haying in the second year; however, the reduction was later offset by nutrient enrichment from livestock manure. Grazing produced 17.6 % more forage DM and 14.8 % more CP compared to haying over the last two years. Root mass, SOC, and air temperature were key factors influencing soil CO₂ and CH₄ fluxes, while soil nitrate-nitrogen mainly affected soil N₂O emissions. Compared to haying, grazing resulted in 22.6 % and 20.4 % lower GHGI for DM and CP yield, respectively.

Conclusions

Grazing offers an effective strategy for optimizing forage production and environmental performance in mixed perennial pastures in continental arid regions.

Implications

Our findings deliver insights into mitigating agricultural GHG emissions and enhancing food security.