Rationally Managed Pastures Stock More Carbon than No-Tillage Fields

Abstract

A significant share of Greenhouse Gases (GHG) produced from agriculture comes from cattle farming. The reduction in GHG emissions from ruminants fed with grains has led some researchers to recommend such a diet as a means of mitigating emissions in the sector. A more accurate balance of emissions, however, must include the carbon (C) stocked by feed crops. Within the grain production system, no-tillage (NT) cultivation systems have a greater capacity to increase and store soil organic carbon (SOC). Within grazing management systems, the rotation used in Voisin's Rational Grazing (VRG) allows the accumulation of SOC through root growth. The objective of this study was to assess the C stock of pasture under VRG and compare soil C stock between VRG pasture and fields under no-tillage management, in two seasons over a period of 1 year. The study included five dairy farms in Santa Catarina State, Brazil. In each property, we collected soil to quantify SOC from VRG pasture and NT fields, in summer and winter. In the pasture, to determine the total stock, we also collected samples from the aerial parts of plants and the roots. Further, we estimated how efficient would be producing milk from those pastures or from those crops. The VRG pasture showed a greater capacity to stock C in the soil than the no-tillage fields (VRG = 115.0 Mg C ha −1 ; NT = 92.5 Mg C ha −1 ; p < 0.00009), with the greatest difference at a depth of 0-10 cm (VRG = 41 Mg C ha −1 ; NT = 32 Mg C ha −1 ; p < 0.00008). In VRG, 95% of C was in the soil, 1% in the aerial part of plants, and 4% in the roots. On pasture was produced 0.15 kg of milk.kg −1 of C stored, and on NT system 0.13 kg of milk.kg −1 of C stored. In this study, we conclude that independent of season, the soil in well managed pastures had a greater stock of C, produced more milk and produced more milk.kg −1 of stored C than fields under NT management. Therefore, when comparing GHG emissions of ruminants with different diets, we must also quantify the SOC resulting from distinct feed production systems.

Effect of recovery period of mixture pasture on cattle behaviour, pasture biomass production and pasture nutritional value

“…Pasture management is the gold standard for increasing the sustainability of grazing systems. While we showed the best RP to reduce the CH 4 emission from cattle, other studies have shown that plants from well-managed pastures also have the ability to sequester C from the atmosphere during photosynthesis (Seó et al, 2017;Stanley et al, 2018). When the amount of C emitted is lower than the amount that is being accumulated in soil by plant roots, we have a positive balance of C, and the livestock emissions are indeed offset (Silva et al, 2016).…”

“…In practice, VRG enables high nutritional value and productive pasture towards improving animal performance, including the reduction of environmental impacts like enteric CH 4 emissions (Stanley et al, 2018). Moreover, VRG pastures are associated with high soil carbon (C) accumulation due to the increase biocenosis that increase and conserve the soil organic matter (Seó et al, 2017) that helps reduce carbon dioxide (CO 2 ) concentration in the atmosphere and further mitigate GHG emissions (Stanley et al, 2018). Moreover, this system can reduce overgrazing, which potentially protects the soil against erosion and degradation.…”

Increasing Dairy Sustainability with Integrated Crop–Livestock Farming

“…Additionally, improving field fertilizer and manure application strategies such as urea (here on corn fields) in conjunction with urease inhibiters could significantly decrease N losses and N 2 O emission from soils [72]. The reduction in GHG emissions from ruminants fed with grains is therefore just one part of the picture, as a more accurate accounting of emissions and milk production must include the C sequestered by feed crops [73]. Here, pastures had greater carbon uptake, highlighting the need to include farm practices in development of GHG budgets [73].…”

“…The reduction in GHG emissions from ruminants fed with grains is therefore just one part of the picture, as a more accurate accounting of emissions and milk production must include the C sequestered by feed crops [73]. Here, pastures had greater carbon uptake, highlighting the need to include farm practices in development of GHG budgets [73].…”

“…Integrated crop-livestock systems can offset more barn and manure emissions, as harvested products remain within the farm boundaries [86]. In addition, pastures have a greater potential to remain carbon sinks throughout all seasons, even when harvested for feed or bedding [73]. Natural vegetation surrounding crop fields, such as forests, hedgerows or grasslands could offset farm emissions even of non-integrated dairy farms, given that~0.3-0.4 ha of such land is allocated per cow.…”