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COUNTRY LIFE IN BC • JUNE 2018 Grazing cattle the sustainable way


Rotational grazing significantly reduces carbon footprint


Iconic images of North America at the time of settlement were ones of vast grasslands, huge herds of bison and a pristine land sparkling with clear water. But today, cattle that graze the range often get a bad rap


Research by MARGARET EVANS


as the poster critters for environmental damage. It isn’t always that way and it doesn’t have to be that way. In fact, cattle can be beneficial to the land. At Michigan State


University, scientists evaluated a system of adaptive multi- paddock (AMP) grass-fed operations as well as grain- fed, feedlot herds. “Our idea of using AMP is as


an overarching term to encompass management [through] intensive grazing, holistically planned grazing and others,” says Jason Rowntree, MSU associate professor of animal science who led the study. “So, effectively, we are attempting to keep forage intake high but likewise allow for adequate plant recoveries such that the plants are not overgrazed.” Despite beef production


potentially being taxing on the land with high greenhouse gas emissions, Rowntree’s five-year study suggests that AMP grazing can offset greenhouse gas emissions and the finishing phase of beef production could be a net carbon sink. Much has to do with a critical understanding of climate and biodiversity on rangeland. “Every micro-


climate is different, however there is a greater and more increasing knowledge base indicating biodiversity is a key to resilience,” says Rowntree. “By overusing animal impact as a tool, or by mismanaging grazing allocation, each action tends to decrease diversity and only the plants that thrive are those that can take high grazing pressure. This outcome can also diminish opportunity for soil organic matter and more specifically microbial biomass and overall soil health. “We have no problem


overusing plants after a killing frost. We treat this as a standing stockpile. In our environment, if we don’t use it then it will rot under a high snow mass. However, we do not want to overgraze plants during the active growing season.”


LINDSAY BARTKO FILE PHOTO


During the finishing phase, scientists evaluated carcass weight and daily weight gain, comparing them to the greenhouse gases from digestion, fermentation, manure storage, feed production and energy use on the farm as well as carbon losses from soil erosion. It was no surprise that AMP


systems came out ahead while feedlot emissions were in the GHG red. But beef production is a complex issue that weighs both environmental consequences as well as food productivity.


For instance, the feedlot model was more productive, producing the same amount of beef on half the amount of land, leaving more resources for other food production or alternate uses. “So, tradeoffs arise,” says


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Rowntree. “First, do we maintain feedlots and minimize overall land use such that land can be used for something else? Or do we try and have more multi-use landscapes that give an overall greater return to the environment? ... I think at the end of the day, we match the production to the environment and have multiple production strategies to enhance ecological resilience and food security.” Rowntree points out that it is not necessarily the number of animals that are grazing but the time they are allowed to graze in a certain area. Clearly, animal impact is the driver behind every management decision. He says it is also important to note that carbon sequestration changes over time. He is hopeful that there is great potential for managed-grazing to offset the methane produced for many


years to come. “AMP is not as productive


as feedlots, based on yields, but the AMP grazing system produced considerably greater amounts of beef on a land basis as compared to continuous grazing, showing that improved management can increase the output of grass-fed beef,” he said. “Ultimately, in a closed system, this implies somewhat lower per capita beef consumption but greater environmental benefits from what is consumed.” He says that feedlot


operations could be more environmentally friendly if they used less fertilizers and cover crops in the grain production component for their feed. AMP grazing offers valuable options for ranchers to graze cattle in an area with relatively high density but then allow for adequate plant recovery. This promotes a deeper, healthier root system and builds organic matter in the soil, which acts as a sponge for moisture.


The study was published in the journal Agricultural Systems.


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