Wednesday, 25 May 2011

What else can soil do for us?

The Soil Science Society of America has published a list of short, medium and long term research challenges that it says is crucial to maximising the potential of the 'single environmental asset that, if protected and nurtured, could help us solve the most pressing problems facing humanity - the soil.'

“Food and energy security, water availability and quality, and climate change adaptation and mitigation are some of the greatest challenges facing our society,” says Chuck Rice, President of the Soil Science Society of America and a distinguished professor of soil microbiology at Kansas State, “Appropriate management of soils offers the potential to provide solutions for each of these challenges.  Soils also provide a direct link to human health as a source of antibiotics and other medical products.”

The research priorities include better understanding the role of soils in improving human and ecosystem health as well as addressing food and energy security and climate change challenges.  Read the research priorities here.

Monday, 23 May 2011

Biochar and nitrous oxide emissions

A New Zealand study shows that the use of biochar can decrease emissions of nitrous oxide, a potent greenhouse gas associated with livestock manure.  The application of biochar to soil can sequester and 'bury' carbon dioxide from the atmosphere in the soil, but it also has the potential to beneficially alter soil nitrogen emissions derived from livestock.  Biochar has been used for soil carbon sequestration in the same manner.

Application of biochar into the soil on New Zealand grazing pasture led to a 70% reduction in nitrous oxide fluxes over the course of the study.   The nitrogen contribution from livestock urine to the emitted nitrous oxide decreased as well.  The incorporation of biochar into the soil had no detrimental effects on dry matter yield or total nitrogen content in the pasture.

Click here to visit the website of the UK Biochar Research Centre.

Thursday, 19 May 2011

Defensive soils improving plant immunity

A report from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the Netherland's Wageningen University has found that plants rely on a complex community of soil microbes to defend themselves against pathogens, in a similar way to the way that mammals harbour a raft of microbes to help fight infections.

Previous work on the phenomenon of disease-suppressive soil has identified one or two pathogen-fighting microbes but this new study has identified a much more complex microbial network.  17 microbes, working together, were identified which suppress the pathogen which causes root fungus in sugar beet.  The scientists behind the work believe that their discovery that 'plants use a tight-knit army of soil microbes for defence' could help to develop better ways to protect crops from disease and therefore reduce wastage.

Soil from a sugar beet field in the Netherlands was studied and it was found that pathogen-fighting microbes in the soil suppressed the pathogen Rhizoctonia solani, which causes root fungus in the crop.  To return the favour of protecting the crop, beet funnels about a fifth of their photosynthetically captured carbon through their roots into the soil to fuel the microbes.

This kind of research ties in neatly with the concept of biological farming, 'a method which focuses on stimulating soil activity, on the basis that healthy soil grows healthy pastures and crops that produce healthy animals.'  Read more about it here.

Tuesday, 17 May 2011

UK Soil Nutrient Balances

The National Farmers' Union (NFU) has recently reported that Defra (Department for the Environment, Food and Rural Affairs) has released  information on  changes in N and P soil balances between 1990 and 2009.

According to the report, soil nutrient balances have been calculated by Defra for England and the UK for the years 1990, 1995 and 2000-2009.  Soil surface balances have also been calculated.  These care the difference between inputs (inorganic fertiliser, manure, N fixation etc.) and offtakes (crop uptake, grass and fodder eaten).  The key findings are:

  • Nitrogen soil surface balances fell from ~140 kg/ha in 1990 to ~80 kg/ha in 2009.  This was not due to a fall in agricultural area since this was only reduced by 0.2% for the same period.
  • Nitrogen soil surface balance fell by 22% in the UK between 2000 and 2009, and 20% in England for the same period.
  • The steady decrease in nitrogen soil surface balance has been driven by reduced applications of inorganic fertiliser and livestock manures.  However, a reduction in the removal of N via forage harvesting somewhat offset the decrease.
  • Nitrogen use efficiency is showing a positive (upwards) trend i.e. efficiency of N use in agriculture is increasing.
  • Phosphorus soil surface balance fell by 54% in the UK between 2000 and 2009, and 64% in England for the same period.
  • Most of the reduction in phosphorus soil surface balance has taken place since 2007 and is a result of a reduction in inorganic fertiliser applications (in 2009) and increased off-take in harvested crops since the removal of set-aside.

Read the full report and an explanation of the methodology by visiting the Defra Statistics page.

Monday, 16 May 2011

Controlled Traffic Farming - improved efficiencies and better soil management

I first heard of CTF a few months ago. It's something of a novel concept here in the UK but in parts of Australia and the US it seems to have taken off. According to, a British website, controlled traffic farming (CTF) is 'a whole farm approach to the separation of crops and wheels; it is a system that avoids the extensive soil damage and costs imposed by normal methods. Controlled traffic is not rocket science - it simply involves confining all field vehicles to the least possible area of permanent traffic lanes.'

' "Plants grow best in soft soil, wheels work best on roads" neatly encapsulates the major conflict at the centre of most mechanised agriculture, and the rationale for controlled traffic farming,' according to CTF and Climate Change, a paper published for the 6th Australian Controlled Traffic Farming Conference. The paper describes how, by combining zero tillage with using tractors and machinery only on clearly identified (usually via GPS) permanent tramlines, and avoiding all movements on other parts of the field, soil structures improve, energy used in subsoiling is saved, water retention improves and runoff declines, resulting in improved yields and / or greater cropping frequency.

There are some technical hurdles to overcome when setting up a CTF system, according to Appropriate agronomy and management is necessary to maximise the potential of the cropped areas and permanent tramlines, and the ideal setup is for all machinery to have the same wheel track so that they all 'fit' the permanent wheelings. In addition, all machinery should have the same span or multiples of that span to avoid covering (e.g. spraying) parts of the field twice. However, the website suggests that this is not absolutely essential – the percentage area of the field 'wheeled' can be reduced to 30 – 40% even with two different track and implement widths.

In addition to the cost of adapting (or purchasing) machinery, CTF systems also benefit from the use of GPS to identify the permanent tramlines, although marker posts could be used as an alternative.

Another paper, simply entitled Controlled Traffic Farming, refers to the use of GPS systems in almost all field systems but also highlights the cuts in fuel, labour and machinery costs as a result of reducing soil damage. 'This makes farming simpler, more reliable and less time consuming. It also delivers environmental benefits, such as reduced water run-off and soil erosion, improved fertilizer use efficiency, less risk of nitrous oxide and methane emissions and improved carbon sequestration.'

CTF has been covered in the farming press but is still a somewhat novel system. A 2008 story in Farmers’ Weekly described a Yorkshire farmer who saw it as a way to ultimately reduce crop input costs by 25%. The farmer, Mr Evison has ditched the plough and power harrow in favour of a Spaldings Flatlift soil loosener, which is often the only cultivator used, to remove any compaction from previous cultivations or harvesting operations. An additional set of discs and packer is used when necessary to create a shallow stale seed-bed for weed control. You can find out more about the costs and benefits of CTF in this Farmers’ Weekly article from 2008.

Wednesday, 11 May 2011

Roadkill compost

I found out today that the state of Virginia is considering getting rid of roadkill by composting it.  The state’s Department of Transportation is considering it as an alternative to sending carcases to landfill – 77% currently end up there and transporting them to such sites costs $4.4 million annually.

I didn’t stumble across this fact by chance.  I Googled ‘roadkill compost’ having heard several years ago about how roadkill was used to make compost in Australia, and wondered what the compost was like and what the opportunities would be for this kind of treatment of British roadkill.  With the increasing deer numbers we’ve seen in recent years and correspondingly higher numbers of dead deer on our roads, ought we to think about this?

According to the Cornell University Chronicle, using a simple composting technique, the Cornell Waste Management Institute (CWMI) discovered it takes about a year to turn deer carcasses into compost that can be used for landscaping purposes along the very roadsides that were the animals' death sites.  The cost of composting a deer is less than $25 a carcass.

As in the UK, deer/car collisions are an increasing problem, especially in rural areas.  Collection followed by landfill or cremation, or roadside burial apparently all have public or environmental health impacts.  But composting, in passively aerated woodchip windrows in which the carcases are buried side by side, is inexpensive, avoids human health problems and provides environmental benefits.

Microbial action in the pile causes it to heat to 110 degrees Fahrenheit (43oC) and decomposition takes around six months.  The high temperatures and microbial processes during composting greatly reduce or kill most pathogens, minimizing the chance of spreading disease and usable compost is available after one year.

Public Works magazine reports that motorists in Maryland kill around 1,500 a year and that the state is turning them into nutrient-rich soil conditioner that combats erosion and sucks up contaminants before they reach storm sewers.

The reports states that unlike vegetative matter, composting deer doesn't require windrow turning.  Because coarse wood chips are used in the process, air flows through the pile naturally. The pile quickly reaches temperatures necessary to break down muscle tissue and cartilage and kill faecal coliform bacteria and Salmonella but that skulls and other large bones, which don't completely decompose, are composted again or disposed of separately.

Unfortunately, I could find nothing about the composition or quality of the compost but Cornell has produced a useful factsheet available here. 

Tuesday, 10 May 2011

Global news from the world of soil

Long term impacts of soil compaction
An article in ScienceDaily earlier this month reported that the damage done to soils by heavy agricultural machinery, causing compaction, was ‘more permanent’ than had previously been believed by researchers.  As well as resulting in reduced yields, soils damaged by compaction would be more vulnerable to erosion and loss of nutrients, leading to water pollution problems.

"It has generally been assumed that structural damage at 25 to 40 centimetres' depth has recovered after ten years. However, our findings show that the pore system and density of the soil are clearly affected even 14 years after the soil was subject to compaction. This may mean that compaction leads to permanent changes," speculates Professor Trond Børresen, one of the researchers working on the Scandinavian study.

Climate change also makes the soil more vulnerable to compaction, according to the professor.

"Driving on wet soil increases the risk of damage to both the topsoil and the subsoil. If the climate changes and we see more precipitation in spring and autumn, we will soon see a lot more damage from soil compaction than we do today," he says.

The agricultural land is also affected by the fact that the weight and size of the machinery have increased significantly during the past ten years.  Read the full story here.

An article in the Express and Echo reports how a Devon farmer has won a progressive farming award for his use of direct drilling as part of a conservation tillage system.

A DEVON farmer who is using state-of-the-art technology to achieve the Holy Grail of modern farming – producing more, with less impact – has won this year's John Neason Award for Progressive Farming, presented by the Devon County Agricultural Association.

James Lee, of Lee Farm Services, based at Shobrooke near Crediton, specialises in using direct drilling to establish arable crops in one pass, so saving fuel and minimising the risk of damage to soil structure.

The technique is particularly useful for establishing winter wheat immediately after maize has been harvested in the autumn, when the risk of soil compaction and of run-off into watercourses is at its greatest, and nowhere more so than on the steeply sloping fields which are characteristic of Mid-Devon, where most of James' customers farm.  Read the full story here.

And from the Coffs Coast Advocate, published in New South Wales, Australia, we learn that this week is a very special week indeed...!

DO YOU know what is special about this week?  Yes it's Mother's Day, but something else has been going on for the past week that you should know about and it's International Compost Awareness Week.

Not exactly the sexiest of subjects and pretty hard to promote but with all the talk of carbon taxes and saving the planet, it's something we all should be involved with.  Composting at both a commercial and domestic level has a multitude of environmental and economic benefits.

Compost returns organic matter to the soil, which improves soil structure, water infiltration, and water holding capacity of the soil.  This has many beneficial implications, including reducing the demand for irrigation water used in intensive agriculture and working towards sustainable yields.  The application of composted mulches can provide a 30% reduction in irrigation water needs.  Read the full story here.

Monday, 9 May 2011

Strip tillage - a new, moisture-saving approach to cultivation

I was fascinated to read a couple of articles in last week’s Farmers’ Weekly on strip tillage, something with which we’re not that familiar in the UK.  Strip tillage is a method of cultivation and direct drilling whereby strips (several inches wide) are tilled leaving undisturbed land in between (so typically no more than 30% of the field surface is cultivated).  Bands of seeds are then drilled into them at wider row spaces than conventional drilling.  So both the row of seeds, and the undisturbed space between, are wider and further apart than in conventional systems. 

The first Farmers’ Weekly article (not available online) highlighted the time and cost savings in establishment using just one pass of the tractor – the farmer featured, Mr Lole, reckoned he saved between £100 and £150/ha by not ploughing, power-harrowing or culti-pressing.  The drill used has been used to drill wheat, OSR, beans, maize and linseed and costs around £25 an acre to run.  Mr Lole reckons that a concurrent £25/acre saving in fertiliser could be made by using strip tillage, neutralising the cost of drilling.

The second article, available here, features Norfolk farmer Stephen Temple who has used strip tillage for the first time this year to grow maize.  Dr Temple reckons that fuel and time savings have been substantial.  In addition, he believes that wind erosion on some soils will be reduced, and the over-wintered stubble will be an asset for wildlife.  He also suggests that inverting and then moving all of the soil in a traditional cultivation sequence causes moisture loss that could delay germination.  But with the strip tillage system only narrow bands of soil are moved, and exposure to drying lasts just a second or two before the drill's press wheels seal the surface again.

"Average annual rainfall on this farm is about 600mm, but this year the spring has been exceptionally dry so far and we had only 15mm between late February and mid-April," he says. "It is a situation where conserving soil moisture is likely to be important, and I think this could an important factor for farmers in low rainfall areas."

Unfortunately, there’s little on the web about strip tillage in the UK – a Google search will throw up one or two Farmers’ Guardian and Farmers’ Weekly articles, but little else about the deployment and use of this technique in the UK, although, as I mentioned in an earlier post, the Centre of Excellence for UK Farming is undertaking some research into the system.

It does seem to be popular in the US, and a number of other countries, however.  The technique was apparently ‘invented’ during the 1980s and US strip tillage seems to differ to the one-pass system described above, in that it is undertaken in the autumn to provide improved drainage and better soil warmth for spring planting.  In addition, fertiliser is often injected into the strips rather than just being spread on top, which reduces wastage and improves utilisation. 

There’s a wealth of information on the web about US strip tillage but there appears to be several different ‘types’ – I came across references to ‘north’ and ‘south’ strip tillage systems as well as systems whereby the earth within the ‘strip’ is not only cultivated but also banked up to 3 or 4 inches tall.  I found a couple of interesting articles from across the pond on it – here and here.

Friday, 6 May 2011

Biological Farming in the UK and New Zealand

Biological farming is a new one on me.  I’d never heard of it back in those heady, far off days when I started this blog (all of five days ago) but in the space of one week I’ve seen three articles on it – one from the UK and two from New Zealand.  My general assumption was that references to biological farming actually meant organic, as in many parts of Europe organic agriculture is known as ‘biologique’ (or the local equivalent) or labelled as ‘bio’, but that is not correct, as these articles show.

The articles from New Zealand, which can be found here and here describe biological farming, or ‘biologics’, as a method which focuses on stimulating soil activity, on the basis that healthy soil grows healthy pastures and crops that produce healthy animals.  The system’s followers believe that modern chemical fertilisers are overused, harm soil biology and produce nutrient-deficient pastures and food.

It’s reported that 450,000ha of New Zealand farmland is now under biological management and proponents argue that there are farmers across the country who can testify to the positive changes they are experiencing.  But biological farming is not organic.  "Biological farmers may still use chemicals if required, but they are buffered or reduced through the additions of biological foods such as seaweed, fish, humates, sugars and more."

However, not all are convinced.  New Zealand soil scientist Dr Edmeades claims that biologics is flawed science and could lead to farms becoming run down.  He believes that the positive results that some farmers are experiencing through the system are due to historic applications of mineral fertilisers, leaving a ‘legacy’ load of nutrients in the soil.

Farmers disagree and claim that biologics is growing and that its leading supporters are among the country's best producers.  They ask how this can be so if the scientists are to be believed.  One farmer switched to biologics after experiencing animal health problems and poor clover production.  He has been applying a "soup" of humates (natural sources of trace elements), fulvic acids, sugar, kelp and seawater, along with small amounts of reactive phosphate rock, nitrogen and sulphur.  Ten years before that, he was a heavy user of nitrogen, phosphorous and potassium before gradually easing off chemical fertilisers.

Farmers’ Weekly (UK) magazine adds a slightly different take to the debate.  It’s report claims that intelligent application of biological agriculture could bring environmental benefits and carbon footprint efficiency, while exploiting natural farm waste products.  Enhanced nutritional performance could also be gained while toxic waste products are microbially digested on site.  The report states that dairy farmers are exploring ways to maximise the benefits provided by slurry while minimising the drawbacks of application, such as poor grass palatability.

One of the drivers for this is therefore replacing noxious slurry or dirty water with a non-toxic bio-available nutrient liquor, which would provide benefits from higher grade bio-fertiliser and reduce problems with sward rejection.  The report says that providing bio-available nutrients to the growing crop would offer more efficient use of a resource while significantly reducing environmental contamination risk.  The bio-slurry would also be soil friendly and help promote valuable earthworm numbers rather than harm the soil – a benefit that should not be under estimated.

Initial trials of slurry-digesting additives are indicating a 30% improvement in N, P and K values compared to treated slurry.  This will usually offer a fertiliser saving more than sufficient to justify the cost of the product, which is likely to range from about £4-8 a cow a year.

According to Farmers’ Weekly, the resulting forage is likely to be better in terms of nutrient balance and will provide benefits to livestock.  The microbial digestion of the slurry is also likely to present a more balanced trace element profile to the plant, via the soil.

It concludes by suggesting that the potential for bio-nutrient use on dairy farms is hugely significant in the modern light of progression.  Fuel needs to be saved, the environment needs to be protected, and above all, healthy productive livestock keep the whole business profitable and enable a better product to be supplied to the human food chain.

Thursday, 5 May 2011

Innovations abroad

I’m an enthusiastic follower of various blogs relating to rural development, in particular Nourishing the Planet and Practical Action. The former referred me to a recent publication which I have been perusing with interest ‘Innovations in Action: Nourishing People and the Planet.’ I particularly enjoyed reading this report as much of the focus was on very practical ways (including highlighting the work of Practical Action) of improving the lives of people in the developing world, from the use of better food storage vessels which preserved fruit and vegetables for longer to better irrigation systems. A number of these innovations relate to soil and water and are summarised below, but I strongly recommend reading the whole report.

Keeping It Cool. . . and Hot
An Israeli company has developed a system that could help farmers beat the heat. Root Zone Temperature (RZT) Optimization technology uses geothermal energy to enable farmers to control the soil temperature at root zones, increasing plant growth and production dramatically. A low-pressure pump, powered by a solar panel, circulates water beneath the soil surface, cooling the ground in the summer and warming it in the winter.

By maintaining plant roots at an optimal 22–30 degrees Celsius, this system boosts plant growth and has increased yields of strawberries, cucumbers and peppers as well as helping crops mature earlier.

Improving the Harvest, from the Soil to the Market
Farmers in Tanzania are fighting a losing battle against increasingly degraded land. Repeated plantings quickly deplete soil nutrients, leaving it barren and vulnerable to erosion. Downstream, the water is dark with sediment, unfit for drinking, and expensive to treat. A CARE International initiative encourages smallholder farmers to use techniques that help restore—and hold in place—the soil.

Farmers and smallholders are building terraces to limit soil runoff and erosion and planting trees as crops on otherwise unused areas of their land. This helps sequester carbon in the soil and restores much-needed nutrients. Farmers are also encouraged to leave sections of their land fallow for one- or two-year periods to give the soil a chance to regenerate on its own.

Putting a Stop to the Spreading Sands
Throughout the Sahel, recurrent drought since the late 1960s is turning formerly crop-covered land into desert. Sand dunes are covering villages, roads, crops, and irrigation systems, making it increasingly difficult to farm and maintain infrastructure. To tackle this, fences are being erected to redirect the wind in order to create artificial dunes. These dunes reduce the strength of the wind and slow the advance of more sand.

The fences are constructed from branches and twigs collected from mature forests and woven together, the materials provide just enough permeability to slow the wind speed while still remaining upright in the face of strong gusts. Long-term barriers are then created by the planting of dry-tolerant and indigenous tree species to act as barriers. As well as restricting the spread of the sand, the natural walls also provide new source of food, firewood, seed, and livestock fodder.

Water from Thin Air
In parts of sub-Saharan Africa, people are forced to travel long distances and to spend hours at a time collecting water from far-away streams or wells. But the residents of Cabazane simply use gravity to let water come to them. At an altitude of 1,600 metres, steel cables held by wood posts support two layers of shade-cloth nets used to catch tiny droplets of water from passing mountain fog.

The droplets create runoff that is captured in gutters beneath the nets and the water is carried by tubes down the mountainside and to the village. Each square metre of netting provides up to five litres of water daily, and most importantly, the water from the clouds is very clean—a particularly valuable commodity in an area that previously suffered from water shortages. The nearest stream to the village, two kilometres away, is contaminated by livestock and a source of disease.

For Pest Control, Follow Nature’s Lead
According to this report, the more varieties of vegetables, plants, and insects that are included in a garden, the less vulnerable any single crop becomes. Mans Lanting of ETC Foundation India wrote in 2007 that the best method of approaching pest control is to learn to live in harmony with pests instead of trying to fight them. By harnessing the natural state of vegetation and pests, a farmer can create “a system in which no component can easily dominate” and in which soil and crop quality is greatly improved.

Traditional farming leads to soil fertility decreasing when crops are harvested, and growing a single crop means that the soil is further stripped of nutrients with each season, requiring the use of inputs that, according to Lanting, lead to an imbalance in plant nutrition and increase vulnerability to pests and diseases. This introduces the need for pesticides, which cost more money and create toxic runoff that can damage the local environment.

Instead, Lanting recommends taking an alternative approach, mimicking the diversity that takes place in nature and creating a garden that relies on natural systems to provide nutrients as well as pest and disease control.

Zero Tillage
Ploughing and other soil-management practices have raised yields in monoculture systems over the last 60 years, but have also done considerable damage to the soil through nutrient loss and erosion. Zero tillage, on the other hand, helps retain soil moisture, prevent erosion, and conserve nutrients.

In Argentina the use of zero tillage in soybean cultivation has led to an estimated gain of US$4.7 billion since 1991, and created 20,000 farming and extension-related jobs between 1993 and 1999. In northeastern India, rice and wheat cultivation increased following the development of zero-tillage drills in the 1990s. Zero or reduced tilling is now used for one-fifth to one-quarter of wheat production and farmers there have been able to increase their incomes $97 per hectare because of improved production and the reduced cost and time for soil preparation. Farmers in Tanzania who used tools made specifically for zero-tillage agriculture saved 75% of the time usually spent on land clearing and field preparation.

Wednesday, 4 May 2011

Perennial wheat?

An article in a recent edition of National Geographic magazine caught my eye.  'The Big Idea: Perennial Grains' describes work being undertaken by the Land Institute and the United States Department of Agriculture (USDA) researchers at Cornell University into developing high-yielding varieties of perennial cereals.

Many of the original species and varieties from which modern crops such as wheat, rice, maize and many other agricultural cereals and vegetables were bred grew as perennial plants.  But, 10,000 years ago, humans made the choice to domesticate annual varieties which die after producing seeds.

Neolithic farmers found that they could rapidly make these varieties better, for instance by replanting the bigger seeds from the more vigorous plants, thus leading to higher and higher yields.  However, perennials didn't benefit from that kind of selective breeding, because they don't need to be replanted.

Researchers today, however, are trying to breed perennial wheat, rice, and other grains.  They are now crossing modern grains with wild perennial relatives to produce plants which have the advantage of perennials – the dense and deep root systems which enable the plants to come back to life each spring as well as allowing exploitation of more of the water and nutrients throughout the entire soil profile – without sacrificing too much of the high yields associated with modern grains.

According to the article, modern, annual cereals can contribute to soil degradation by depleting the topsoil leading to reliance on large quantities of imported, often mineral, fertilisers to maintain high yields. And large fertiliser applications can generate their own environmental problems, such as water pollution.  In addition, leaving the soil bare before and after drilling annual crops can lead to weed invasions.  The main problem highlighted, however, is the erosion of the soil associated with cultivations.  In the US around 1.7 billion tonnes of soil is lost each year, and one estimate suggests that the rate of soil erosion globally at ten to a hundred times the rate of soil formation.

The report argues that perennial cereals would help to address many of these problems, by keeping the ground covered, reducing the need for pesticides, and their deep roots would stabilize the soil and make the grains more suitable for marginal lands.  Their deep roots would also make better us of water and nutrients from deeper in the soil profile.

Yields, however, are still too low to compare with those in the US, but not necessarily with poorer parts of the world, such as Nepal, where yields are lower.  The researchers are optimistic that with the use of cheap DNA sequencing, field-testable perennial maize could be available within ten years.

Tuesday, 3 May 2011

A few interesting titbits.....

A handful of stories I've come across or been referred to today:

The Centre of Excellence for UK Farming has published research on a variety of topics including several which are soil-related.

The new farming systems research programme is looking at systems that are capable of reducing energy reliance, while maintaining cost-effective and efficient production systems.  Three themes are covered - cover crops, cultivations and soil amendments.

The PROSOIL Project, the aim of which is to develop a producer-led co-operative to test and develop the concept that optimising soil health within primary agricultural systems can improve the financial efficiency of livestock production in an environmentally-sensitive way.

And a project looking at the development of strip tillage techniques in UK arable production is examining the operation of strip tillage equipment on varying soil types and exploring the effect on soil structure and crop performance.  It is also looking to further develop strip tillage as a cultivation technique for use in a range of arable crops including oilseed rape, sugar beet, maize and field beans.

Find out about these and other projects here.

An article in Scientific American argues that soil depletion is behind declines in the nutritional quality of fruit and vegetables. 'Modern intensive agricultural methods have stripped increasing amounts of nutrients from the soil in which the food we eat grows. Sadly, each successive generation of fast-growing, pest-resistant carrot is truly less good for you than the one before.'

The Financial Times (registration needed) reports on the International Centre for Biosaline Agriculture in Dubai. Because of the increasing salinity of Middle Eastern soils and groundwater, crop plants are increasingly valued for their value for withstanding salt. A number of types of major crops, including barley, have been identified which can withstand high levels of salinity, which affects more than 25% of irrigated land globally. 

Conservation agriculture: Opportunities for the UK?

I have become very interested in the idea of conservation agriculture (CA) recently and, in particular, what opportunities there may be for using it more widely in the UK.  Amir Kassam from the University of Reading is a name well-associated with this concept and one which pops up frequently, and he feels that CA has a considerable role to play in European agriculture.

In a recent paper published in the Journal of Farm Management, Professor Kassam describes conservation agriculture as being characterised by three sets of mutually reinforcing practices:

  1. Continuous no or minimal mechanical soil disturbance (i.e. direct sowing or broadcasting of crop seeds; minimum soil disturbance from cultivation, harvesting or farm traffic);
  2. Permanent organic matter soil cover, especially by crop residues and cover crops; and
  3. Diversified crop rotations in the case of annual crops or plant associations in the case of perennial crops, including legumes.

He argues in relation to the three big challenges identified in Defra’s August 2009 first Food Security Assessment that ‘the approach used and the analysis applied in the Assessment do not address the unsustainable nature of the intensive tillage-based production systems.  Consequently, there is no explicit attempt made to elaborate on what new advice must be formulated for farmers on what changes must be made to current production techniques and practices to make farming more sustainable and environmentally friendly as well as productive and profitable.’

Prof. Kassam is critical of this and other reports published by Defra which do not elaborate on specifically what it is within current intensive agricultural systems which lead to soil degradation and what the remedies are, other than the undefined ‘best practice in soil protection’.  He argues that 'the solutions for much of our agricultural soils are likely to be based on how we can manage the whole soil-crop-landscape system for ecosystem services (including for food and water provisioning) without the use of the plough and the harrow as well as uncontrolled heavy farm traffic.’

Interest in CA has grown during the past two decades, as has the evidence that this ‘win-win agricultural production system’ can help to address the ‘unsustainable characteristics of modern tillage agriculture’.  In the 1940s Edward Faulkner in his revolutionary “Ploughman’s Folly” stated that ‘no one has ever advanced a scientific reason for ploughing’.  CA has achieved economic and environmental benefits wherever it has been introduced and it is increasingly being promoted as making a real contribution to sustainable intensification.  It can do this because it:

  • Provides and maintains an optimum environment in the root-zone to a maximum possible depth.
  • Ensures that water enters the soil so that (a) plants seldom suffer water stress that will limit the expression of their potential growth; and (b) residual water passes down to groundwater rather than over the surface as runoff.
  • Favours beneficial biological activity in the soil to (a) maintain and rebuild soil architecture, (b) compete with potential in situ soil pathogens, (c) contribute to soil organic matter and various grades of humus, and (d) contribute to capture, retention, chelation and slow release of plant nutrients.
  • Avoids physical or chemical damage to roots that disrupts their effective functioning or limits their maximum potential for nutrient uptake.

Prof. Kassam identifies a range of benefits provided by CA, which I have summarised here:

  • Large and demonstrable savings in machinery and energy use, and carbon emissions        
  • A rise in soil organic matter content and biotic activity
  • Reduced erosion
  • Increased crop-water availability and drought resilience
  • Improved recharge of aquifers
  • Reduced impact of climate change-induced weather volatility
  • Reduced production costs, contributing to increased profits
  • More reliable harvests and reduced risk

While CA has been adopted widely across many countries, it has only rarely been ‘mainstreamed’ as an approach to sustainable farming within agricultural development programmes or backed by policy, so the global coverage of CA remains small, at only around 7% of total crop land.  It has been promoted in some EU Member States via the European Conservation Agriculture Federation (ECAF) but it has neither been widely publicised nor seriously researched.  Other barriers include cultural ones, such as a traditional reliance on ploughing, as well as the need for a deeper understanding of ecological processes; CA is therefore knowledge intensive.  In Finland, Germany and Spain the adoption of CA is being encouraged and subsidised in order to address soil erosion, but its adoption in other Member States seems to be driven by economic, rather than environmental influences.

Prof. Kassam appears to subscribe to the ‘growing conviction’ that CA has an important role in transforming agriculture everywhere towards a more sustainable and efficient system.  However, he identifies a number of barriers to the widespread take-up of this type of farming, principally the belief that soil tillage is essential for agricultural production.  In order to foster the widespread take-up of CA, he argues that Europe should rely on (a) the evidence and successful experience outside Europe; and (b) establish a network of publically funded on-farm operational research in which farmers can be provided with an opportunity and financial support to experiment with CA practices and adopt them to suit their socio-economic and agro-ecological conditions.  In addition, the engagement of the machinery sector to develop a new set of mechanical technologies for CA farming will be necessary.

The paper concludes by stating that EU governments must ‘make a firm and sustained commitment to encourage and support CA’.  I agree that this is a desirable objective.  However, in the UK soil loss is generally not a significant issue across much of the country (soil loss to rivers and other water bodies, resulting in contamination and eutrophication clearly is a problem, however).  Without the driver of substantial soil erosion and thinning soils, which are common problems in other parts of the world, in spite of the multiple other benefits of CA we might be waiting some years before we see its widespread adoption in the UK.

Monday, 2 May 2011

Ants and termites – doing for Australia what earthworms do in wetter climes?

I first heard about this study while listening to the weekly CSIROpod(cast) from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) based in Canberra, Australia.
The paper, published in Nature Communications, described an Australian study investigating the role of ants and termites on crop yields in dryland agriculture. According to the researcher, Dr Theo Evans, while ants and termites have traditionally been considered pests they may actually provide to dryland agriculture the same kind of benefits that earthworms provide in wetter areas. The study found that where these insects were present, wheat yields increased by as much as 36%, soil water infiltration was improved and soil nitrogen (N) levels were higher.

The precise mechanisms for increasing N were unknown, but termites, which in wheat fields will feed mainly on protein-deficient stubble, use symbiotic gut microbes to fix atmospheric N, in a similar way to legumes. This fixed N is used to make protein for the termite and excess is excreted through defecation, which helps to raise N levels in the soil. Concerns regarding damage to wooden buildings and other infrastructure caused by termites are unfounded as the majority of termite species found in Australia don't eat wood.

Ant and termite populations can be encouraged in the same way that farmers in wetter regions encourage earthworms, such as by reducing soil disturbance through the use of conservation agriculture, as well as simply ploughing shallow and less, using controlled traffic farming to reduce compaction and reducing use of agrochemicals.

The study, conducted in the northern edge of the West Australian wheat belt, also found that ants fulfil a secondary purpose of eating weed seeds. While ants also tend to prey on termites, the two insects are often found in the same habitat. Both types of invertebrate build nests in the soil and provide similar types of ecosystem services.