Monday, March 7, 2011

The Importance of Rotational Grazing In Solving the Problems Which are Confronting Agriculture

Rotational grazing along the Creeper Trail, South Fork of the Holston River Project. Virginia. 2002.

Bring back rotational grazing! It will be necessary in confronting climate change, expensive oil and oil depletion, fertilizer availability, and the preservation of soils. To follow, I have several sources which each approach this important subject in a different way. Grazing is as close as we can come to the original prairie ecosystems which combined native prairies with large herbivores.

This first section is from an organic agricultural talk given in January of 2010 by Dr. E. Ann Clark of Guelph University. It focuses upon facing up to a reality of agriculture using far fewer fossil fuel inputs.

Post-oil design drivers will also necessarily demand not just organics but novel agri-food systems emphasizing local/decentralized food production, and seasonal consumption expectations, from minimally processed foods. Evidence will be presented to show that organic is not enough, however. Ecological soundness will require a de-emphasis on annual cropping coupled with re-integration of livestock, both to mimic the principles that sustain Nature and to dramatically reduce dependence on fossil fuels.


What drove us to an agri-food system that reportedly consumes 19% of the national energy budget - but only 7 of the 19% are used on the farm, with the remaining 12% incurred by post-farmgate transport, processing, packaging, distribution, and meal preparation (Pimentel, 2006)?


But those seeking to ensure food production in a post-oil future must first explicitly acknowledge that agriculture was never designed to be sustainable - not ecologically, not economically, and not socially sustainable, at least for primary producers.... The question is whether the current flawed design can be refined to enable sustained food production in the post-oil era - or not. And if not, then what to replace it with? Although the time of onset of the post-oil era is unclear, the time is now for research, extension, and education to prepare the way for it... academic curricula can no longer justify an agri-food system that burns up millions of years of accumulated solar energy to grow, process, transport, store, package, and sell a few hundred years of food.


The opportunity to ship and extract profit over geographically large areas advantages those willing and able to consolidate to mega-scale proportions for production and processing. Specialized businesses tailored to producing vast quantities of bulk, homogenous product necessarily exclude or co-opt smaller scale operators by driving down prices, narrowing the profit margin, and forcing farmers to ‘get big or get out’. Thus, the cheap energy that enables bigness is very much the driver for the specialization/consolidation/globalization trajectory that has so marked our recent past.


Anticipating the end of cheap oil gives us the freedom, and indeed the responsibility, to conceive, validate, and refine alternative designs driven by a new suite of predictable design drivers... In simplest terms, living on current rather than stored solar energy is an absolute prerequisite to inter-generational equity - enabling our children, and indeed all of the earth’s children, to be sustained in the future.


Rising energy costs will preclude continued reliance upon energy-dependent inputs. Synthetic N alone currently accounts for about 40% of the energy budget of grain crops, encouraging a shift toward biological N fixation, but also toward less extreme levels of labile N.


What About Organic Yields? ...When studied systematically, however, organic yields can be quite comparable to conventional yields, particularly after the 3-5 year transition interval... over a 9 year interval in Iowa, showed no significant difference in yield for corn, for soy, or for wheat yields when grown in conventional versus organic systems... However, it must be noted that the longer rotations typical of organic management mean corn may be grown once in 5 or 7 years, compared to in alternate years in a typical corn-soy rotation. Thus, total corn production in 10 years time will be much less in an organic system... organic and low-input yields reportedly already surpass conventional yields in the Third World.


Ecologically sound agriculture - including organic agriculture - will necessarily rely less on annuals and more on perennials - with a central role for grass-fed livestock. And let me re-affirm that this does not mean less vegetables, as these account for barely 2% of arable land in Ontario... Exporting an acre of land as meat, milk, or eggs means a fraction of the implied nutrient export of grain or vegetable crops... [horses, cattle, sheep, and goats evolved to consume grass and some woody species; pigs can consume diets largely or wholly made of grass, while grass can be part of a diet for chickens and turkeys]


I put it to you, then, that whether fruit and nut trees or grass swards, perennials will have to account for a much larger share of the agricultural landscape if our goal is ecologically sound agriculture... Designing for the post-oil future means tailoring agricultural crops, practices, and expectations to the soil, climatic, and managerial constraints of each region. And for much of North America, that means a whole lot less annual - and especially grain - cropping. In other words, tailor the agriculture to fit the environment, rather than trying to shoehorn-in annual crops to an environment suited to perennials.


Does this reasoning mean replacing all those annual vegetables we like and need with even more meat, milk, and eggs than we already eat? No. The grass ley system formalized by Stapledon and Davies (1948) facilitates the production of needed annuals by rotating annuals for direct human use with perennials to be grazed or conserved for livestock. In this system, an interval of 1 to several years under perennial sod is rotated with an interval of 1 to several years of annual crops, to produce what we need while at the same time, meeting the needs of Nature... Livestock - because of the forages they consume - are in fact a critical foundation to ecological sustainability.


The sooner that academics and government policymakers acknowledge the implications of post-oil for the structure and function of agriculture - and education in agriculture - the easier it will be to design and educate for the future.

PDF Source


Photo: Cattle grazing.
Growing tall fescue and allowing moderate grazing by cattle can help restore quality to soil degraded by decades of plowing, according to new ARS research. Photo courtesy of Alan Franzluebbers, ARS.

The USDA's March 2011 Agricultural Research Magazine includes the articles:
Cattle Pastures May Improve Soil Quality
  • Land that was grazed produced more grass than ungrazed land, and grazing led to the most carbon and nitrogen being sequestered in soil. Sequestering carbon and nitrogen in the soil has become a major goal for agriculture because it reduces greenhouse gas emissions. Whether grass was grazed moderately or intensely made little difference on sequestration rates.
Conservation Grazing Uses Livestock as Ecosystem Engineers
  • One way that conservation grazing can be accomplished is with controlled late-fall burns.
  • Other conservation grazing techniques include varying the seasons and the areas in which cattle graze, adding sheep and goats to the livestock mix, and varying livestock numbers and animal densities.

Can Livestock, Prairie Dogs, and Fire Coexist?

Dairy Farmer Finds Unusual Forage Grass


Recently, here on this blog, under my post, "NYT's Room for Debate: The Uncut Version on Why we have High Food Prices" a reader posed the question, "Would love to hear more explanation behind this statement: 'Those who think that vegetarianism is the answer need to understand the science of the natural world's symbiotic relationship between plants, soils and animals.'"

This was my answer:
Thanks for your respectful question. I'm looking at this from the perspective of being a good steward of land you might own but also use to produce food to feed people in a sustainable way. If you care for your soil you will be rewarded with strong production. This is explained in "Omnivore's Dilemma" discussing Polyface farm quite well. Here are four references for you to get you started:

An Alternet interview of Gene Logsdon about his new book "Holy Shit": here

Rodale Institute Hogs on Pasture: here

Wikipedia on Permaculture: here

And Wikipedia on Polyface Farm and Joel Salatin: here

These methods are more like the way farmers rotated livestock and crops during the first half of the past century.


Though I don't agree with Savory that this effort would be enough to mitigate CO2 emissions, his work is important:

Allan Savory of the Savory Institute: The focus of the Savory Institute is to restore the vast grasslands of the world through the teaching and practice of Holistic Management and Holistic Decision Making. The Institute's Consulting and Training activities are turning deserts into thriving grasslands, restoring biodiversity, bringing streams, rivers and water sources back to life, combating poverty and hunger, and increasing sustainable food production, all while putting an end to global climate change.


  1. Do you have the correct web address for the link that is called "PDF Source"? It directs to a gmail account?