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Energy & Agriculture and Tillage & Soil Management In a post-peak fossil fuel world with a warming climate Dr Charles “Merf” Merfield

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Presentation on theme: "Energy & Agriculture and Tillage & Soil Management In a post-peak fossil fuel world with a warming climate Dr Charles “Merf” Merfield"— Presentation transcript:

1 Energy & Agriculture and Tillage & Soil Management In a post-peak fossil fuel world with a warming climate Dr Charles “Merf” Merfield

2 An electronic copy of this presentation is available from

3 Not a simple topic! There are no simple answers This presentation therefore is a bit of a meander! –It starts by looking at the big picture –Then it looks at some practical things you can do on your farm I hope that it will inform and entertain It wont give you a ‘recipe’ to take home I will leave plenty of time for Q&A

4 Putting the energy ‘crisis’ in perspective

5 The earth’s energy flows 3.85 x 10 24 Joules / yr Energy captured by photosynthesis = 3 x 10 21 J / yr which is 0.078% of solar flow Human energy use = 2.2 x 10 20 J / yr which is 0.0057% of solar flow To scale! 3,850,000,000,000,000,000,000,000

6 Not all energy is equal There is no shortage of energy - the sun will continue to shine for billions of years Therefore there will be no shortage of sun derived energy, i.e., solar, wind, hydro, etc., Fossil fuels are clearly finite, over a period of decades to centuries (depending on type) Fossil fuels are the key driver of climate change We therefore must stop using fossil fuels, but even if we don’t they will run out in human time scales

7 Agriculture and energy Agriculture is the original source of managed energy for human civilisation in the form of food to power humans and livestock. All of the energy was originally captured by plants (photosynthesis) Supplemented by small amounts of other renewable, e.g., water and wind mills, in the last few thousand years

8 Agriculture and energy Fossil fuels (fossil photosynthesis) utterly changed the situation Agriculture was rapidly deposed as societies main source of energy (mostly relegated to food energy) It is now impossible / impractical to turn the clock back: e.g., Europe consumes ten times the amount of energy that is produced by its farms in the form of food

9 Agriculture and energy Agriculture has not just be deposed as humanities energy source: It is now as addicted to fossil fuel as the rest of society –To power the machines that have supplanted muscle power –To provide the ‘inputs’ to drive yields, especially Haber–Bosch nitrogen Trying to (completely) replace fossil energy with farm derived energy (biofuels) is a circular impossibility!

10 Agriculture and energy Agriculture needs to change its energy use: –To minimise its climate change impact –To move to renewable energy While continuing to provide humanity with healthy food, fibres, ecosystem and other services that are essential for civilisation to continue Not a big ask then!

11 The drivers of climate change Climate change is not simply due to the CO 2 released by burning fossil fuels There are five main greenhouse gases: CO 2 equivalents –water vapour (H 2 O)N/A –carbon dioxide (CO 2 )1 –methane (CH 4 )25 –nitrous oxide (N 2 O)298 –and ozone (O 3 ) N/A

12 Agricultures climate footprint Methane and nitrous oxide are produced in large amounts by agriculture –Methane by ruminants and from manure –Nitrous oxide from nitrogen fertilisers and anaerobic soils (especially rice paddies) Chart next page

13 Agricultures direct contribution to climate change

14 Agriculture and fossil fuels Agricultures direct net CO 2 contribution to climate change is negative, because while it burns fossil fuels releasing their CO 2 to the air it uses photosynthesis to pull CO 2 out of the air in much larger quantities. However, the captured CO 2 quickly gets back to the atmosphere when the food is eaten, but that is not counted as agricultures problem!

15 Indirect contributions Production of Haber–Bosch nitrogen fertilisers uses around 1% of global energy - all from fossil fuels The agricultural supply chain, e.g., machinery production, distribution and destruction / recycling also produces considerable amounts of GHGs

16 A fine mess! Clearly reducing agricultures climate change impact is not a simple matter Trying to find simple solutions is therefore likely to get us into another finer mess than the one we are currently in!

17 Thinking holistically Many of the current problems created by science & technology are due to philosophical reductionism Many of the proposed solutions and analysis of the fossil fuel problem are also reductionist and are therefore flawed Its essential to consider the issue holistically / i.e., using a system based approach

18 Food miles Based on the energy used to move food from farm to plate: but, it is only fossil fuel energy that matters and it fails to include the energy used in all the other aspects of production Recent example of a pineapple produced in a greenhouse in the UK - very local, very few food miles, cost $10,000 and the total energy used many times that of an imported pineapple!

19 A little breather! How about a few questions / clarifications on matters that may be unclear?

20 Climate change and your farm Practical steps to reduce your farms climate change impact, and potentially improve your farming and profitability at the same time First some caveats If you think that science would have a firm grip on such matters, you would be making a mistake… The following points provide some critical fundamental underpinnings to reducing tillage

21 No-till and soil organic matter No-till systems are widely considered to increase the level of soil organic matter (SOM) (of which carbon is a key component) This is so widespread no-till is about the only farming practice that is considered reliable enough in building SOM / soil carbon to be included in carbon markets

22 Tillage and soil carbon

23 Tillage and soil carbon sequestration - What do we really know? It is widely believed that soil disturbance by tillage was a primary cause of the historical loss of soil organic carbon (SOC) in North America, and that substantial SOC sequestration can be accomplished by changing from conventional plowing to less intensive methods known as conservation tillage. This is based on experiments where changes in carbon storage have been estimated through soil sampling of tillage trials. However, sampling protocol may have biased the results. In essentially all cases where conservation tillage was found to sequester C, soils were only sampled to a depth of 30 cm or less, even though crop roots often extend much deeper. In the few studies where sampling extended deeper than 30 cm, conservation tillage has shown no consistent accrual of SOC, instead showing a difference in the distribution of SOC, with higher concentrations near the surface in conservation tillage and higher concentrations in deeper layers under conventional tillage. These contrasting results may be due to tillage-induced differences in thermal and physical conditions that affect root growth and distribution. Long-term, continuous gas exchange measurements have also been unable to detect C gain due to reduced tillage. Though there are other good reasons to use conservation tillage, evidence that it promotes C sequestration is not compelling.

24 Tillage and soil carbon John Baker is one of no-till’s top komatua. That he has said there is no reliable evidence for no-till to increase soil carbon is a big deal

25 Will the real SOM destroyer please stand up?

26 Soluble nitrogen and SOM When the use of soluble (bag) nitrogen fertilisers first became widespread it was claimed that they would increase SOM due to increasing crop growth, so increasing the amount of organic matter returning to the soil Good old bad reductionist thinking

27 Soluble nitrogen and SOM Most bag N fertiliser is not directly taken up by the crop - only about 15% goes straight into the plant The other 85% first cycles through the soil biota - which is mostly microbes Give the microbes a load of soluble N and they need a carbon source to ‘balance’ it out That carbon source is SOM

28 Soluble nitrogen and SOM The evidence from long term trials and real- world nitrogen fertiliser use efficiency is clear Soluble nitrogen fertilisers cause soil microbes to consume SOM in greater amounts than the extra crop residues can replenish Therefore, bag nitrogen use, reduces, not increases, SOM

29 Haber–Bosch nitrogen If you want to do one thing in farming to reduce your climate change impact stop using Haber–Bosch nitrogen –It’s production consumes ~1% of global fossil energy –Its application on land is responsible for most of agricultures nitrous oxide emissions –It is a key cause of SOM / soil carbon loss –And it has a truck load of other downsides, especially water pollution

30 “There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don’t know. But there are also unknown unknowns. There are things we do not know we don’t know.” Donald Rumsfeld (philosopher poet?)

31 Tillage, climate change and energy With the scientific world still arguing (often heatedly) about how agriculture and soil management affects climate and GHG emissions, giving firm recommendations is something of a fools errand! However, these are my best bets (known knowns) and I hope that there are not too many unknown unknowns lurking!

32 Step away from the tractor Even though the impact of tillage on SOM is now muddier than before, it is still something we need to reduce, even if just because most tillage requires power from fossil fuels (animal draft operators can now feel very smug!) So why do we till (cultivate) the soil?

33 Tilling for all the wrong reasons Many people think we till to make the soil ‘better’ for crops to grow However, no-till / no-dig shows that as good, even better crops can be grown without tillage (with some caveats) Originally the primary purpose of tillage was vegetation (weed and crop residue) management –No-tillers call glyphosate ‘chemical ploughing’

34 Tilling for all the wrong reasons Nick Poole from FAR says The reason for much of tillage today is so that ‘poorly designed’ seed drills can pass through the soil

35 Tilling for all the wrong reasons Many standard agricultural, and especially horticultural seed drills and planters have planting mechanisms that will ONLY work in loose, friable, residue free soil No-till has clearly shown that such a tilth is not required for good crop establishment No-till has in fact clearly shown that such a tilth can be a hindrance to crop establishment!

36 Tilling for all the wrong reasons The almost universal belief is that you need a fine seedbed for good seed-to-soil contact so that seeds can take up water to germinate Problem is that is utterly wrong! Seeds don’t take up liquid water, they take up water as a vapour / gas

37 Stewart B. Wuest, Stephen L. Albrecht, and Katherine W. Skirvin Seeds only take up water as vapour Seeds germinating above liquid water germinate faster the closer they are to the liquid. Seeds germinating in holes in the soil, but without touching the soil germinate without difficulty

38 No-till and germination Most of the research in no-till was on getting the design of the drill sorted out Much of that was on the correct drill slot Baker developed the inverted T drill slot

39 Baker, C. J. & Saxton, K. E. (Eds.). (2007). No-tillage Seeding in Conservation Agriculture, 2nd Edition. Wallingford, UK: Food and Agriculture Organization of the United Nations.

40 Tilling for all the wrong reasons Ideally we would only do enough tillage to kill existing vegetation and then use seed drills and transplanters that can cope with high residue levels This requires a whole new suite of tillage and planting equipment! This requires agronomists and machinery manufacturers to talk to each other!

41 Organic min-till Full (continual) no-till is not an option (yet) in organics Min-till is an organic option Min-till (generally) means non-inversion tillage that only disturbs the top few centimetres of soil Min-till is being used (by two top farmers) Friedrich Wenz and Richard Gantlett

42 Photo courtesy of Friedrich Wenz




46 Non-herbicide min-till While it can be done, it’s not easy, err, its pretty dam hard Not an option for the faint hearted or without a lot of experience and a dab hand with the welder Lots of research and new equipment needed to make it mainstream

47 Non-herbicide no-till Also know as crimper rolling Independently discovered several times –South America – 1980s –North America 1990s Oregon State University – John Luna Rodale Institute – Jeff Moyer Others ?

48 Cover-crop no-till cash-cropping Grow a weed suppressing cover-crop / green manure Kill the cover-crop by rolling with a crimper- roller or similar tool at full anthesis (CCP) Plant cash-crop directly into flattened cover- crop residue / mulch Mulch provides weed suppression and other benefits, e.g., nitrogen

49 © 2009 Rodale Institute

50 All photos © 2009 INIA, Uruguay

51 Rodale Institute in USA Rodale doing a lot of work on crimper rolling in USA (Pennsylvania) Video… Listen out for the cash / cover crop combinations used

52 © Rodale Institute

53 Crimper rolling When it works, it can work really well When it fails, failure can be total (complete crop loss) Lots of ducks to get in a row: –Right cover crop(s): sowing time, growth pattern, time of flowering, weed suppression, N supply to crop –Right crops: planting time, growth habit, weed suppression –Etc., etc., etc., etc.,

54 Crimper rolling Trial at the BHU indicated –Our climate is not well suited (winters too warm and heat unit accumulation in spring too slow) –May be useful for a few crops It is not full / continual no-till, it is only no-till in the spring following the cover crop, I have not seen any no-till transition from the cash crop into the next cover or cash crop

55 Phew, nothing sounds easy! While min-till, crimper rolling etc., sound great they are not easy to implement Compaction management is something everyone can implement, often at little cost, and for great benefit After soil nutrients, compaction has the next largest effect on crop yields and profitability Compaction is a major cause of anaerobic soil, which is a major source of GHGs from soil


57 Compaction The negatives of compaction have been known about since before the mechanisation of agriculture Farmers and growers still consistently fail to implement compaction management systems Result is higher tillage costs / energy use and lower yields

58 Davies, B., Eagle, D. & Finney, B. (1993). Soil management (5th ed.). Ipswich: Farming Press Books. See also Davies, B., Finney, B. & Eagle, D. (2001). Resource Management: Soil. Tonbridge: Farming Press Books.

59 Compaction management Two rules of thumb –The heavier the machine the deeper the compaction –The higher the tyre pressure the denser the compaction Compaction is not removed by removing the tyre tracks - compaction is much deeper - below the plough layer

60 Davies, B., Eagle, D. & Finney, B. (1993). Soil management (5th ed.). Ipswich: Farming Press Books. See also Davies, B., Finney, B. & Eagle, D. (2001). Resource Management: Soil. Tonbridge: Farming Press Books.

61 Compaction management Use as small / light machine with the minimum tyre inflation pressure as possible for the job (yeah, right!) Very rarely done due to the cost of multiple tractors and amount of mucking about with weights, tyre inflation and water ballasting Controlled traffic - the easier answer

62 Controlled traffic farming (CTF) Create permanent (or multi year) places in the field for machinery wheels and human feet (tramlines / wheelings / paths) The rest of the field is then free from traffic and foot compaction and benefits hugely Like organics and no-till, the hard core CTF mob are fanatical - notices on gates, traffic police, Sunday worship, etc.,

63 Controlled traffic farming (CTF) Total adherence to the faith is not required to get considerable benefits: keep to the wheel marks as much as possible, and live with the odd transgression (do a penitence) For vegetable farming use vegetable beds. For broad acre farming use the tramline system

64 Controlled traffic farming (CTF) How do you stay on the same wheelings from year to year, especially after pasture? If you’re a big flash farmer there is GPS If your not, use fenceline markers, e.g., painted post, batten, or dedicated marker poles - this works well for veg beds as well - e.g., mark every 10 th bed

65 Reverse action tillage Where there is a need for the standard fine tilth, reverse action tillage is worth while investigating Normal tillage, e.g., plough, deep spring tine, rotary hoe, power harrow, surface working, e.g., harrows and rolls, are often working a lot of soil just to get the top 5 cm fine and loose enough for the seed drill Uses lots of energy, time and creates lots of compaction

66 Reverse action tillage Reverse action tillage, instead of trying to break up lots of soil to get a fine seedbed, works by separating out the already fine soil from the clods, plant residue and stones, and putting the big stuff down below and leaving the fines on the top The machines are generally referred to as ‘stone buriers’ e.g., RotaDarion


68 Reverse action tillage Advantage is a fine consolidated seedbed in one pass, with considerable time saving possible, and less compaction and total energy used Disadvantage is the machines need to be tough, so good ones are expensive, they are power hungry so need a powerful tractor for the size of machine) and are even slower than a rotary hoe

69 Renewable powered machines Growing interest in electric / renewable powered machines, e.g., – –


71 Downsizing A lot of the time we use machines that are much bigger than required - there is a lot of opportunity for machines matched to needs Two wheeled tractors –Uncommon here, but a mainstay in many parts of Asia where many farms are under 5 ha


73 © copyright 2010 Steam weeding Ltd Two wheels good, four wheels better?

74 Conclusions Reducing your farms impact on climate change is not just a case of using less fossil fuel Stop using synthetic N fertilisers Soil management is also critical Keeping soil in good health, i.e., high organic matter and minimising compaction are key Some changes are easy - e.g., controlled traffic, while others, e.g., min-till are hard Start with the easy steps first!

75 Energy & Agriculture and Tillage & Soil Management In a post-peak fossil fuel world with a warming climate Dr Charles “Merf” Merfield

76 Question time

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