Uncovering cover crops

Cover crops are very much a hot topic at the moment.  They seem to have so much to offer – improved soil structure and organic matter, retained nutrients, erosion limitation, and even blackgrass control.  But not everyone is convinced of their merits.  It’s all very well farmers with light land in the south extolling their virtues, but what of the rest of us?  And in these challenging economic times, do they pay?

We don’t have the answer to all these questions, but we are learning a lot about the potential of cover crops on cold wet Midlands clays through a rigorously designed experiment that has been running for the past year.  The research is part of our contribution to Defra’s Sustainable Intensification research Platform (SIP).  We are still analysing the data, but I can share some interim findings.

We looked at three different mixtures, oats and Phacelia; oats, Phacelia and radishes (oil and tillage); and oats, Phacelia, radishes and legumes (vetch and clovers).  We also had a bare stubble control plot in each of the three fields in which the experiment was replicated.  Our Soil Scientist, Dr Felicity Crotty has been gathering data on soil physical, chemical and biological properties, while our Farm Manager, Phil Jarvis is gathering yield and economic data.

Soil Scientist, Dr Felicity Crotty

Felicity quantified the effect of drilling the cover crops on soil structure in comparison to the bare stubble control which had not been driven over by machinery, and by the end of the winter, the soil structure had visibly improved and compaction was reduced in all the cover crop treatments while the bare stubble control remained unchanged.  The oats, Phacelia and radish mixtures had slightly greater plant cover, but importantly, significantly lower biomass of weeds such as blackgrass.  There were some significant differences between cover crop mixtures in soil biology, specifically surface dwelling earthworms and millipedes, which may have implications for organic matter breakdown and incorporation into the soil.  The radish based mixtures were also associated with the highest yield in the following spring oats crop, and lowest weed biomass, compared to the stubble control plots.  Further analysis, especially of the economic data, will enable us to evaluate these mixtures more fully.

Our interim findings for the first year suggest that cover crops can reduce weed populations and enhance yield through improvements in soil function, but we now need to discover whether such benefits justify the cost incurred by establishing the cover crops in the first place.  Meanwhile, cover crops have been established in a new experiment this autumn, this time looking in more detail at the specific components of the mixtures so that we can understand better the role of each species. 

The spring oats following last year’s cover crops have now been replaced by wheat.  Next year we will assess the yields of that crop in relation to the different cover crop mixtures.  Our aim is to understand the implications of cover crops, not just in terms of immediate costs and benefits, but also as part of a rotation.

Brexit - the long view

Now that the full ramifications of Brexit for farming, the environment, and all they provide for the UK population are becoming more fully appreciated, perhaps it is time for reflection.  A few years ago we did this by bringing together the latest agri-environmental science with the earliest available local community knowledge.  It was a fulfilling experience in improving our collective understanding of our past, present and, most importantly, our future management of the land.  The book that resulted from this project is now freely available from the British Library by clicking Exploring a Productive Landscape .

We recognised then that we have a few challenges ahead of us, not least the multiple increasing impacts of climate change, a growing national and global population, declining availability of natural resources such as land, fuel and nutrients, and economic pressure from global markets.  Brexit will influence the strategies adopted to address these issues in future.

There have been bigger changes before of course.  Dispersed Roman and Anglo-Saxon farmsteads were replaced by the feudal medieval open field system which, in turn, gave way to enclosure.  These were largely closed systems in which resources were recycled locally.  Without the protection of the Corn Laws, late nineteenth century steam power increased exposure of national food production to global markets and resulted in a long period of depression for the rural population. National food security was prioritised in the Second World War, and the 'Green Revolution' contributed to increased food production, world population growth, and our dependence on fossil fuels. How significant Brexit is in the context of these historical events remains to be seen, but there is no doubt that the consequences for the way the British countryside works for us all could be considerable.

Our membership of the EU has coincided with a period of increasing realisation that the recent historical trajectory is not sustainable.  EU-funded research collaborations across Europe have helped improve our understanding of agri-envionmental issues, and funding has been made available to reward farmers for delivering services that bring no immediate economic benefit to the farmers themselves, but result in multiple benefits to the wider population as a whole.  My involvement in a scientific review of agri-environmental issues for the EU back in 1999, first highlighted for me the wide range of scales, impacts and people associated with the management of soil alone.  Now we are embarking on our latest EU-funded research project, SoilCare, which specifically addresses the public and private benefits of improved soil management.

A combination of history and science reminds us that the delivery of this mix of public and private benefits must be a fundamental requirement for future agricultural policy.  As our research at the Allerton Project highlights repeatedly, a multifunctional approach to land management, delivering benefits at a range of scales, is what we need to aim for to achieve both an economically vibrant farming industry and an environment which underpins the health and wellbeing of our society as a whole. We increase the importation of food from outside Europe at the expense of social and enviromental damage elsewhere in the world.  There are increasing concerns that the implications of this for us are not confined to a troubled conscience, but contribute to increased risk of social and political unrest, as well as to multiple local and national impacts of global climate change. The world is a smaller place than it has ever been before.

The dialogue in Exploring a Productive Landscape seems particularly poignant now, given the constraints on farm profitability and public funding.  Economic uncertainy outside the EU means that we need to use the limited resources available to us more efficiently and more wisely than ever before.  The task now is firstly to develop, secondly to promote, and thirdly to support the methods by which farmers can deliver healthy soils, woods, wildlife and water, while also providing the food and energy that we all demand.  That will have a cost, but it is one that must be paid, not just for us, but for those who take up the baton for the next stage in our history.

Soils research underlying land management

Both the farming and scientific communities understand that soil physical properties influence our ability to produce food and make money from the land.  There is also an increasing acceptance that soil biology plays a role.  But how are soil physical and biological properties related? This is the question posed by Leicester University PhD student Falah Hamad.  He is currently in his second year of data collection.  At Loddington and another site in Cambridgeshire, he is collecting data across a range of land uses and soil conditions, from compacted arable land, through better structured arable soils and pasture, to established woodland.

Falah Hamad measures CO2 emissions from pasture

As well as soil physical properties and organic matter, he is carrying out repeated surveys of earthworms and measuring CO2 efflux as an indicator of soil microbial activity at each of the sites.  His results are already revealing how earthworm numbers respond to reduced soil disturbance, and how compaction and soil organic carbon differ across land uses.  These data also provide a valuable baseline for our continuing research at Loddington, and provide new data for pasture and woodland to help us build on our existing knowledge of arable land use.  They will help us understand some of the biological process underlying (literally) our management of the land.

This is useful to us, and helps us provide guidance to farmers and advisors through our ongoing knowledge exchange programme, but is it what farmers want to hear?  The knowledge and interests of scientists and farmers are not always perfectly aligned!  This is the subject of another PhD project being carried out by Stephen Jones from Nottingham University.  He is taking an interdisciplinary approach, combining social and natural sciences to compare the attributes attached to soils by scientists and farmers.

Are farmers and scientists looking for the same thing in soil?

In his research, Stephen will be interviewing arable farmers from a range of backgrounds to find out what they want soils to deliver for them.  He will also be gathering data on the soils themselves to apply scientific physical, chemical and biological attributes to those soils.  Such properties are relevant to the whole range of 'services' that soils deliver for society and to the policy objectives of government.  But how well matched are these societal and scientific objectives with those of the people actually managing the land?  Combining social and natural sciences within one study will help us find out and guide our future knowledge exchange activities.

Celebrating songbirds

It seems remarkable that I have now been monitoring songbird numbers at Loddington for a quarter of a century, carrying out eight early morning transect counts each summer.  Over that time, our research has expanded to cover a wide range of agri-environmental issues, influencing both policy and practice on individual farms, but our monitoring of bird numbers has continued unchanged throughout.  Long-term datasets such as this provide an insight into issues which cannot be explored through short-term research projects.

Linnet - now abundant at Loddington again

Long before the term ‘ecosystem services’ came into use, we carried out research into several wildlife species, recognising the important role they play in helping to meet our needs.  We have looked at spiders and predatory beetles in field margins and beetle banks because of the role they play in controlling aphids and other crop pests.  We have researched bumblebees, solitary bees and other pollinating insects because of their role in fruit-set of wild and cultivated plants.  We have investigated aquatic invertebrates which provide an indicator of the quality of our drinking water supply, and we are currently investigating earthworms and other soil invertebrates because of the important role they play in soil function.

Where does this leave birds?  Let’s accept that birds have an important cultural value.  Birds inspire us.  They provide the focus of attention for millions of bird watchers across the world, and bring satisfaction to countless others who observe them more casually.  Farmers are no exception.  As our recent PhD student, Susanne Jarratt was able to demonstrate, farmers learn about birds through their participation in agri-environment schemes and develop an appreciation of them.  Nearly a thousand farmers across the UK took part in this year’s Big Farmland Bird Count.  And let’s not forget that it was the study of grey partridges in Sussex, started by Dick Potts in the 1960s, that inspired the research that underpins our current understanding of the farmland ecosystem.  More recent research demonstrated that songbirds such as skylarks and corn buntings benefit from the management of farmland for partridges.

So what about the songbirds at Loddington?  What have my two hundred early morning bird counts revealed?  They show that songbird numbers have changed considerably in response to game management on the farm.  Following a baseline year in 1992, when we made no changes to the management, songbird numbers had doubled by 1999 following seven years of management for wild game.  From 2001, we kept the habitat management going, but stopped the predator control, and then from 2006, we also stopped the provision of winter food.  Songbird numbers dropped until, in 2009, they were little higher than the 1992 baseline. 

Songbird numbers are once again almost twice as high as in the baseline year of 1992

Introducing a reared pheasant shoot with limited predator control in 2011 did not result in the increase we had seen in the early years of the project.  However, research carried out by John Szczur and Patrick White identified the importance of predator control for some species and we have taken the decision to increase predator control specifically for these birds in the past couple of years.  Songbird numbers are now 90% higher than they were in 1992, while numbers in the wider countryside remain relatively constant.

While not all birds have increased, those which have include iconic species such as song thrush, whose song is appreciated by numerous visitors to Loddington each spring, and the more subdued spotted flycatcher which makes the remarkable 8,000 mile round trip from West Africa to join us each year.  Tree sparrows are now on more or less permanent view from our visitor centre, and blackbirds, linnets and chaffinches are amongst the other species to be thriving.  That is surely something to celebrate.

SoilCare - our European collaboration continues

The UK electorate has voted, by a small margin, for a massive change in the relationship we have with our European neighbours, and in the way our own country will operate in future.  But some things are bigger, even than the European political stage.  Without healthy soils, we will fail to support society at national or international scales, whatever its form of governance.  Despite the results of last week's referendum, we can, thankfully, continue to collaborate with European partners on research into the maintenance of healthy soils through the EU funded project, 'SoilCare'.

Irrigated maize field at Coimbra, Portugal

 The Allerton Project is one of 16 research and demonstration sites across Europe which will be developing management practices that improve the immediate profitability of farm businesses, while also ensuring the underlying environmental sustainability that is essential to maintain that into the future. As is being increasingly widely appreciated, we need to consider the needs of future generations, as well as our own.  I was fortunate to be able to visit the Portuguese partner, Escola Superior Agraria at Coimbra earlier in the month and to learn about the challenges and opportunities there.

The research agenda for the next four years will be set, not just by the researchers involved, but by a network of local stakeholders around each of the study sites. Like our colleagues at Coimbra, we have been meeting with local people over the past two weeks to capture their concerns and priorities for research.  Project partner, Professor Mark Reed joined me from Newcastle University for the first of these meetings with members of the Welland Valley Partnership's Resource Protection Group, and I met subsequently with members of the Welland Arable Business Group and participating farmers in the Water Friendly Farming project.

Welland Valley Partnership members discuss the options

Together, these groups have strong farmer representation, ensuring that our objectives are practically grounded and relevant to farm businesses.  But we have also captured the views of others with an interest in the soil because of its role in controlling water flow, influencing water quality, and sequestering carbon. We look forward to comparing the outcomes of these meetings with those from other partner countries, identifying differences and similarities, and perhaps developing new ways of thinking about this international issue ... together.

Integral integration

I have just got back from two days in Penrith where I was involved in the organsation of the Institute of Fisheries Management's 'Farming and Fisheries' conference.  The focus of the session I chaired was sediment, with speakers from the length of England, and one from Ireland, covering issues associated with maize grown for anaerobic digestion, lake sedimentation, and sediment impacts on aquatic invertebrate communities and food webs. John Quinton from Lancaster University ended the session with a description of the evidence based practical mitgation measures that arable farmers can adopt. Much of this research was carried out with us at Loddington. We ended with an enlightening discussion.

On the second day, I had the chance to present some results from the research we are doing with Jeremy Biggs of the Freshwater Habitats Trust and Colin Brown at York University in our Water Friendly Farming project.  Like the conference as a whole, this project highlights the inter-relatedness of many issues associated with land and water management.  Nothing can be considered in isolation. This was also the theme of an article I wrote for the latest newsetter of the Sustainable Intensification research Platfrom (SIP), an abstract of which appears below.

Integral integration

'Sustainability' is generally regarded as meeting our needs today without compromising those of future generations.  We are all becoming increasingly comfortable with the idea that a range of environmental factors underpins our ability to produce food, clean water and, to an increasing extent, fuel.  Look no further than the recent flurry of activity around soil health on farming-related social media as evidence of this.  Integrating environmental objectives with agricultural ones is fundamental to productive land use, both in the short and long-term.

There are two further ways in which integration is key to our productive management of the land.  One is a response to the polarisation of farming systems.  While this may have delivered economic efficiencies in the short-term, there is an increasing realisation of the benefits associated with the integration of food production systems, not least in terms of waste management, weed and disease control, and security of feed supply. The other example relates to knowledge exchange.  A long history of one-directional knowledge transfer, from scientists to farmers, is gradually giving way to a more enlightened approach, in which the skills and knowledge of the most pioneering farmers are recognised as having equal, or more relevance to the current challenges associated with food production.  Put the best scientists and the most forward thinking farmers together and we have real dynamism that can help us to achieve sustainable intensification.

‘Intensification’ now is not measured in tonnes of fertiliser or litres of diesel or plant protection products, but through the knowledge and technology that are developed and applied to improve the efficiency with which those resources are used.  As well as ensuring economic and environmental benefits arising from improved resource-use efficiency, this approach harnesses natural processes for nutrient cycling and control of pests, weeds and diseases.

Integration of environmental and production objectives, arable and livestock systems, and scientific and farmer knowledge, is integral to the activities on the SIP study farms.  Together, our farms provide a platform on which science can be applied in a practical setting, and a focus for discussion with visiting farmers and advisors. 

The full version of this article, and the rest of the SIPSCENE newsletter can be found here.

Big cover-up

There is increasing interest in the role of cover crops in improving various aspects of soil function such as soil structure for growing crops and soil erosion reduction.  Cover crops such as various brassicas, oats, rye, vetch, Phacelia and buckwheat are sown soon after harvest and destroyed prior to drilling the following spring crop.   Such over-winter green cover is eligible for funding under Countryside Stewardship or Ecological Focus Area (EFA) requirements so could potentially cover a large area nationally.

Through root growth, return of plant material to the soil, and associated soil biological activity, cover crops have the potential to increase soil orgainc matter, improve crop rooting capacity and nutrient uptake, increase infiltration and reduce soil erosion and asociated impacts on watercourses.  But perhaps this is all too good to be true!  We certainly need to understand more about the benefits on different soil types, and importantly, also the limitations and costs involved.

We are experiemntally testing both simple and complex mixtures of cover cops at Loddington

As part of our research with the Sustainable Intensification research Platform (SIP), we have set up experimental plots of cover crops comprising a simple EFA mix, a more complex EFA mix, and a fertility building mix, as well as a control (bare stubble) plot, replicated across three fields.  Working with our SIP partners, NIAB TAG, our Soil Scientist, Dr Felicity Crotty, is gathering data on a range of soil biological, physical and chemical properties across all the plots.  Very early results from the autumn suggest little difference in soil biology across the treatments, but slightly higher soil compaction in the plots that were sown with cover crops than in the control stubble plots. Data currently being gathered will reveal whether there have been any changes over winter.  With help from Agrii, we are also monitoring changes in soil moisture through the soil profile across the plots in two of the experimental fields.

Our Soil Scientist, Dr Felicity Crotty and NIAB staff gather cover crop data from experimental plots at Loddington

We also need to consider implications for the following commercial crops and will capture crop cover and yield data, as well as associated economics, across the experimental plots this autumn.  A spring oats crop in one field of cover crop plots last year delivered a yield that was about 20% higher than the bare stubble plot, sufficient to cover the costs of establishing the previous cover crop, but such benefits do not appear to follow through to the wheat crop that has followed the oats.  We need to consider implications across the rotation, rather than for individual crops, and also different crop management practices. Comparisons of cover crop destruction method (sheep grazing vs. spraying) and establishment method for the following winter wheat are on our research agenda for the coming year.  Watch this space.  We will reveal all!