Posted on:Mar 19, 2013 11:12 pm
Intensive grazing systems (of which Savory’s is one) are the subject of considerable science discussion. Some are successful within a narrow set of circumstances, but the over-riding factor to all studies is seasonal rainfall (‘if it rains, grass grows’). One 14-year study used satellite data across South Africa to compare grazing practices, while removing the dominant influence of rainfall/grass growth - http://www.sciencedirect.com/science/article/pii/S0140196303001071. This study found that the higher stocking rate of intensive grazing systems resulted in a consistent reduction in above-ground biomass when compared to non-selective grazing, and the more ‘intensive’ grazing resulted in higher reduction of biomass. In other words, intensive grazing practices result in less grass cover. Sorry Alan!
Drought stops any grazing system in its tracks. Long-time Australian pasture agronomist and climate scientist Greg McKeon explains the "hydro-illogical cycle" as:
- it rains, grass grows, graziers stock up
- drought comes, graziers hold on to stock due to lower prices
- drought continues, herds remove all edible grass
- rain comes, washes away the (unprotected) soil
- cycle continues
This has led to a dramatic long term deterioration of soils and native vegetation on the world’s rangelands – see http://www.longpaddock.qld.gov.au/about/publications/pdf/preventingdegradation.pdf .
Climate change – hotter, drier droughts, more flooding rains – will only accelerate the degradation of grazed rangelands.
Also noteworthy is the failure of traditional intensive grazing in Russia, Siberia, Mongolia, Kazakhstan, China and eastern Africa where large herds are constantly moved by traditional herders (as the Savory method does) – but sheer weight of livestock numbers has ravaged these landscapes in drought years, leading to more degradation. China has gone to great efforts to reverse desertification, (google Great Green Wall), and is discovering that in marginal areas the most effective method is re-planting native perennial grasses, and removing all livestock – see http://www.chinadialogue.net/books/4772-Books-simple-ecology-complex-issues/en.
Please, let’s have some sanity in this debate. The number of ruminants now trampling planet earth is beyond belief. Ruminants evolved about 50 million years ago, and by the year 1500 there were about 200 million on our planet. Now there are 2 billion, and only 75 million are wildlife! Each year we breed 64 billion livestock (mostly chickens), that’s about 9 animals per person per year globally (28 animals per person per year in the USA). To grasp the enormity of this, imagine your family’s ‘entourage’ of yearly animals following your around, and think of the pressure they are placing on our finite planet.
The best aspect of Savory’s method is that burning is stopped. Burning is a very effective tool to stop forests re-growing, but half of Africa is high rainfall savannah, which will revert to forest if the burning were stopped – see http://www.nature.com/nature/journal/v478/n7369/full/nature10452.html. After a few years when African herders see their grazing lands overtaken with trees, they will turn back to fire. To see the extent of this burning just take a look at the NASA fire maps - http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD14A1_M_FIRE.
‘Conservation grazing’ - http://theconversation.edu.au/can-livestock-grazing-benefit-biodiversity-10789 does work in regions where consistent rainfall and pasture production can support the cost of fencing and labour, but is not a cure-all as Savory proposes.
There is enormous potential in above ground and below ground carbon sequestration, but this will only happen when we stop burning the daylights out of grasslands to remove dead grass and to stop ‘woody weeds’; and when we remove grazing pressure.
Retired Principal Scientist, Natural Resources Department, Queensland, Australia