Building Carbon in Soil
Studies on grassland grazing soils confirm healthy soil is a valuable buffer for dry times; soil carbon levels and measurements in fields and systems will take time to build
Winnipeg, MB (March 29, 2021) – Two recent soil-focused studies done in part on the benefits of grazing systems in Manitoba are showcasing the connection between grazing and improved water infiltration into the soil, a positive impact in production which may bode well for some of the forecasted dry times ahead on Canada’s Prairies.
However, as far as Manitoba Forage and Grassland Association (MFGA) is concerned, what is also becoming increasingly clear is that while water infiltration is seen as a window into healthy grazing-based soils that have the potential to be sequestering carbon, registering and documenting statistically significant numerical increases in soil carbon will take time.
Dr. Terence McGonigle of Brandon University recently finished two years of a three-year project funded by Manitoba Agriculture and Resource Development on six Manitoba fields that was developed to complement a Canadian Forage and Grassland Association Agricultural Greenhouse Gas Project on same fields that wrap-up this year. During similar time periods, University of Alberta researchers, Dr. Mark Boyce and Dr. Edward Bork, recently presented results of their Adaptive Multi-Paddock (AMP) Grazing Study in Workshops held on Wednesday, March 3rd and Thursday, March 4th hosted by ALUS Canada.
A connected story to the AMP study on the University of Alberta website states that AMP grazing uses a rotating system that has livestock graze in a smaller environment for a short time, typically less than one week. Livestock are then moved to another paddock, giving the vegetation a chance to recover before being grazed again after several weeks.
“With more grass and more days of grazing needed for livestock production, improved water infiltration, improved plant communities and enhanced vegetation biomass and litter are all signals of healthy soil and productive lands,” said Larry Wegner, MFGA chair. “Both projects have shown this to be true on the grazing lands that can provide production benefits while having a greater ability to buffer the impacts of climatic events such as droughts and floods via the water infiltration abilities of the soil.”
Wegner touts MFGA’s belief that any farmer operating their farm in ways that put more carbon into the ground is doing good service to the greater community. He says that beneficial management practices and the focus on water and soil management focus of some regenerative agriculture practices naturally bode well for health of the soil as well as the greater ability of the soil’s water infiltration abilities to get through potentially challenging times. Wegner says the soil health aspects of on-farm water management will be a key component of MFGA’s participation in the Federal Government’s carbon consultation opportunity currently under way.
“The drive to adopt practices is in the positive outcomes seen on the land by the producers and not necessarily motivated by a higher test soil carbon value at this time,” says Wegner. “Soil carbon measurement and markets are complex and still-developing and most of us are learning very quickly as we go along.”
Wegner has been using soil-boosting, planned grazing practices on his Virden, Manitoba-area farm for the last 15 years. He says that he recently heard a presentation that stated farmers need to be prepping for drought three years out. He figures some Manitoba producers might be right on that exact path should dry times prevail in coming months. Still, a drought is a beast no one ever hopes to see.
“It’s important to start prepping for a drought in the wet years,” says Wegner. “Remember a properly managed pasture can respond quickly after a rain but an over-grazed pasture can take years to recover…. if ever. You can NOT feed yourself out of a drought so it’s critical to have a plan.
To Wegner’s points, while the grazing studies both identified improved water infiltration – a widely-accepted litmus test for healthy soil - measuring soil carbon at the levels necessary to shoulder a carbon system will take time. This is because measuring soil carbon is variable as every farming system and soil type is different and the gains will need to be assessed over time. The uniformity of the fields and datasets in the two studies will be valuable in that regard.
-30-
SIDEBAR 1: TWO GRAZING STUDY HIGHLIGHTS
· McGonigle’s GHG study measured shallow cores to 15 cm depth taken in all years. However, additional deep cores to 100 cm depth were taken where possible across field sites in 2020, diving those deep cores into depth intervals.
· McGonigle’s study has one year remaining under Manitoba Agriculture Resource and Development and pinpointed values for carbon stock that ranged from 96 t ha-1 under sandy conditions at one southwest Manitoba farm to 176 t ha-1 on a farm field located within southern Manitoba’s prairie pothole region.
· McGonigle’s study advised bale grazing provides a pronounced stimulation of grass cover in the location of the former bale. Infiltration rate was determined as 5.2 cm hr-1 under continuous grazing and 5.7 cm hr-1 under planned grazing.
· The AMP grazing study detailed improved water infiltration, enhanced vegetation biomass and litter as buffers against drought
· The AMP grazing study declared benefits via the absorption of methane into the soil and more soil organic carbon.
SIDEBAR 2: Larry Wegner’s DROUGHT PREPARATIONS
· Amalgamate your herds
· Do a forage inventory and match the livestock to the forage inventory
· Prioritize your herd into sustainable carrying categories
o A - keeper herd
o B - can be sold but would prefer keep
o C - will be sold if it gets dryer
o D - can be sold anytime
· Talk to Manitoba Agriculture Resource Development staff to help make a plan
· Connect with producers that have grass when the others do not. What are they doing different?
-30-
For more information:
