Friday, 25 May 2018

The case for broader buffering benefits

Grass margins around fields are readily adopted by farmers within agri-environment schemes but are sometimes criticised for failing to deliver on the environmental objectives for which they are intended.  But such criticism often arises because too narrow a focus is taken on the benefits.  These include the ability to cut hedges later in the winter, after berries have been eaten by birds, and the provision of a habitat for pollinating insects and invertebrate crop pest predators. 

Our research into both field margins and the productive area can guide the development of integrated land management
The greatest potential is where grass margins are placed against watercourses, including ditches and small streams, as well as rivers.  Used in this way, their capacity to reduce movement of soil to adjacent watercourses is well established.  We have found that earthworm numbers are more than twice as high in grass margins as in the adjacent field, helping to improve infiltration and reduce surface runoff to water and acting as a refuge for recolonisation of cultivated land, as well as providing a food source for wildlife.

What plant species establish as a result of sowing or natural regeneration also influences the benefits realised by grass margins, as does their subsequent management.  We are exploring the traits and associated benefits arising from a range of perennial herbaceous plant species, with the aim of delivering multiple benefits.  The establishment and management of riparian woodland, where appropriate, is an extension of that process.

Buffer strips can be further enhanced by creating buffer pools within them to capture runoff, as we have been doing at Loddington since the 1990s, although the efficacy of these is limited on clay soils where very fine material is held in suspension.  Additional barriers within field boundary ditches serve a similar role. We have shown that, although eutrophic, pools fed by runoff can have additional biodiversity benefits for birds, amphibians and insects.  Where more permeable dams are installed in field boundary ditches or small streams, these have the potential to buffer downstream areas from flood peaks and we are currently evaluating these in our Water Friendly Farming project. Stacking multiple buffering measures requires additional knowledge, investment and management but increases the value of public benefits delivered from the same area of land.

But we know that each of these measures in non-productive areas has only a limited role in reducing the movement of sediment and nutrients to watercourses and additional measures need to be adopted within fields to improve soil function, reduce soil erosion, and deliver other benefits such as enhanced terrestrial biodiversity.  Research at Loddington has identified the potential of tramline management and reduced tillage intensity for example, and as reported in my March post, we have also explored the potential role of cover crops, and are currently investigating grass leys. An integrated approach to land management needs to be taken to meet environmental objectives, incorporating targeted evidence-based management of both productive and non-productive areas.

How effective these measures are varies considerably from time to time and place to place, a subject I will return to in a future post, but each of them has a place for their cumulative impact.  With new funding mechanisms for agri-environment schemes currently under consideration in the lead up to Brexit, there is considerable potential for a number of options to enhance the standard grass margins that are now widely adopted across the country.  One solution might be a modular approach to buffer strips with bolt-on options, but crucially, each adopted according to site specific, local circumstances.

It is vital to recognise that we can’t rely on buffers outside the cropped area alone, however elaborate they might become in some situations.  Soil management within the field, reducing erosion in the first place, is fundamental to catchment management and to meeting other environmental objectives, with a range of options for differing soil types.  But these require attention to detail, timely operation, capital investment, technical advice and support, and in some circumstances reduce crop yields.

There are still unknowns and a need for continuing research, and we continue to play a major role in that at Loddington, but we know enough about a range of field margin and in-field measures to adopt a package for improved land management that delivers food production alongside other public benefits.

Friday, 13 April 2018

Getting together around soil

If we felt we had got to know our local farming community fairly well over the past 25 years of the Allerton Project's existence, that process has stepped up a gear in the last couple of years through our shared interest in soil.  Today, a dozen farmers met at Loddington as part of our Soil Biology and Soil Health project with AHDB, led by Elizabeth Stockdale at NIAB.  'Health' assumes life, and this project explores the relationship between life in soils and farm production.  Several other farmers expressed regret at being unable to attend because cold, waterlogged, lifelss soils associated with the recent rains had delayed many arable operations and added considerably to the current workload for both arable and livestock farmers.
Our research brings together local farmers through EU, Defra and AHDB funded soil research projects at Loddington
As part of the Soil Biology and Soil Health project, we are investigating the impact of ploughing experimental plots through a long-term no-till field at Loddington and documenting the changes in crop performance and soil properties (of which more another time).  We also want local farmers to take soil samples on their own farms to contribute to our collective understanding of the relationship between soil management practices and agricultural activities and production, through their influence on the biological activity of soil.

More to come in due course - the home page
A related initiative provides an opportunity for local farmers to collect soil samples for analysis and compare their results with those from other local farms, similar soil types, or comparable farming systems locally, or elsewhere in the country.  This project is at an early stage, with the first soil samples only just being taken, but results will be uploaded in due course to the interactive website at where participating farmers will be able to compare their soil properties with those on other farms and consider the implications for their businesses.

In our EU funded project, SoilCare, local farmers have played a key role, through a carefully structured process, prioritising what research we should carry out.  As a result, we are now comparing a range of modern deep-rooting agricultural ley grasses, gathering data on forage yield and quality, and on changes in soil properties, including infiltration rates.  We are also experimenting with different ways of alleviating soil compaction and gathering data on crop performance and soil biology, as well as on changes to the physical properties of the soil itself.  Those farmers who were able to get to Loddington today were able to view these experimental plots and discuss the visible differences in crop performance.  Our research on cover crops as part of Defra's Sustainable Intensification research Platform (SIP), also provided an opportunity for local farmers to view and discuss experimental plots at Loddington (see last month's blog post).

While there is considerable interest from the farming community from the perspective of agricultural production and profitability (in an economic climate which makes this objective increasingly challenging), each of these research projects also has considerable relevance to catchment management. Foremost in many of our minds during the recent period of prolonged heavy rain is the potential for reducing flood risk.

Saturday, 17 March 2018

Cover crops research

The potential of cover crops to reduce impacts on water are fairly well understood, but the agricultural benefits are less clear, especially on the clay soils that are found across much of Lowland England.  Over the past two years this issue has been investigated by our Soil Scientist, Dr Felicity Crotty as part of our contribution to Defra's SIP (see my December blog post).

Sprayed off cover crops at Loddington, March 2018

In 2015/16, we tested three different cover crop mixtures against a control (no cover crop present), replicated across three fields.  In 2016/17, we tested the individual component species in those mixtures, with three replicates in the same field.  The first experiment adopted various mixtures of cereal, phacelia, radish and legumes, while the second experiment tested oats, phacelia, vetch, buckwheat and radish individually.  In each case, we monitored a range of soil chemical, physical and biological properties, as well as cover crop and weed cover, and the yield and weed cover in the following spring-sown oats crop.

Cover crop mixtures containing radish generally supported 4 times higher numbers of surface dwelling (epigeic) earthworms. Control plots had up to twenty-three times as much weed cover as cover crop plots.  In the following spring-sown oats, the yield, although low, was 60% higher in plots which had contained these cover crop mixtures, and the amount of black-grass and other weeds was up to six times higher in the control plots than the plots which had contained cover crops.

In the single species cover crop experiment, by February, epigeic earthworm biomass was 3.5 times higher in the radish plots than in the control.  Weed cover was over 5 times higher in the bare stubble control plots than in oats and radish plots which had good cover of the planted cover crops.  This provides a clear indication of the ability of some cover crops to supress weeds.  The yield of spring oats was 20% higher in plots which had previously contained radish compared to the bare stubble control plots, but overall yields were again low and the difference was not statistically significant.

The low weed burden in the spring-sown oats is likely to be due to improved rooting conditions for the cash crop and associated crop vigour and competitive advantage, rather than to supression of weeds in the cover crop. In fact, while a sparse, open-structured crop may have lower benefits to the soil in terms of organic matter contribution for example, higher germination of weeds in the cover crop provides more opportunity for weed control when the cover crop is sprayed off in late winter.  Such are the trade-offs associated with cover crops.

On clay soils in the Midlands, establishment of cover crops occurs later than on lighter soils and more southern locations, resulting in a less dense crop than can be achieved in more favourable conditions.  Cover crops also do not reach the stage of maturity that occurs elsewhere with the result that physical means of cover crop destruction such as crimping are not feasible and a glyphosate application is necessary, even if the cover crops are previously grazed by sheep.

While the costs of cover crops remain constant from year to year, the benefits are likely to vary with weather, harvest and soil conditions.  While weed control and water protection benefits are realised in the first year, cover crops that improve soil properties may have longer lasting implications for crop performance and water quality.  These are issues which are of considerable relevance to the economics of adopting cover crops and their role in environmental improvement.  New research being carried out at Loddington over the next few years will contribute further to this debate.

Wednesday, 6 December 2017

Sustainable Intensification - the foundation is laid

The Allerton Project has played a major role in Defra's Sustainable Intensification research Platform (SIP) over the past three years as one of the five research and demonstration farms in the SIP network. The wider SIP consortium has involved around thirty partners, and last week, most of us attended a three day conference to present our results, share lessons learnt, and discuss options for the future.  The aim of the SIP was always to establish a network of farms and associated research partners as a foundation for continuing collaboration on research into management practices which address economic, environmental and social objectives in agriculture.  The need for such a network is greater now than it has ever been.

Nigel Kendall (Nottingham Uni.) shares research results with visiting farmers
For us at Loddington, the SIP enabled us to carry out our first research into grass and livestock systems.  As a result of the research carried out by Nottingham University School of Veterinary Science, we now have a better understanding of how availability of trace elements such as selenium and cobalt vary spatially between fields and seasonally through the spring and summer, and how sheep respond to these changes.  Such an understanding is important to our ability to integrate livestock and arable systems, bringing grass leys into the rotation so that they perform optimally for both arable and livestock interests, while also delivering for the environment through reduced flood risk, improved soil structure and water quality, and benefits to biodiversity. A summary of this work is available here.  The collaboration with Nottingham University is one we are continuing, with further work already being undertaken on grass and livestock systems. 

The SIP has also enabled us to carry out research into the potential economic and envirommental benefits of cover crops, and into issues associated with landuse change at the catchment scale.  Cover crops are increasingly adopted on lighter soils and in southern England where they are valued by farmers for the benefits they bring to soil structure, organic matter and nutrient cycling, and subsequently to the following cash crop.  On clay soils further north though, the benefits are less clear.  Growing conditions mean that harvests are later and soil conditions are cooler and often wetter when cover crops are drilled, resulting in poorer establishment and associated benefits.  We were able to explore these issues and I will report on this another time, but you can download a summary here.

Our catchment scale work within the SIP was built into our existing Water Friendly Farming experiment and involved using the grass weed herbicide propyzamide as a focus for discussing with farmers a wider range of ecosystem services associated with landscape scale soil and water management.  Both the plot scale cover crops research and landscape scale work on propyzamide are centred around soil as the key natural capital asset for any farm business.

Throughout, we are aiming to develop management practices which benefit both the farm business and the environment, optimising the use of natural resources to achieve this.  Terms such as 'sustainable intensification', 'ecosystem services' and 'natural capital' are commonly used in discussing this broad issue, but each represents a form of jargon that sits uncomfortably with many people.  This is especially so when these terms are promoted with doctrinal zeal which can be confusing and offputting.  It is almost as though such language is used to distance the speaker from the listener - more to instill authority than understanding.

But these terms do have an important role in furthering our understanding, not least through the limitations that each of them has.  As an apparent oxymoron, 'sustainable intensification' does this well, highlighting the tension between maximising production now and ensuring production is maintained into the future through a healthy environment, and pointing the way towards an approach in which both can be optimised.  'Ecosystem services' emphasises the need to improve our understanding of the environmental trade-offs underlying, not just production but multiple other benefits to society, but also reveals the need to recognise those aspects of our environment from which there is no obvious or immediate benefit to society. While 'natural capital' highlights the need to value this broad range of natural resources, it also highlights the limitations associated with making that value purely economic, revealing our lack of knowledge to make that possible, even when it might be desirable.

Such considerations can guide future research to fill these knowledge gaps, but we need to leave the jargon behind when it comes to translating those research findings into guidance for practical management.  Knowledge exchange has been a central part of the SIP, as it has for the Allerton Project throughout the past quarter century.  It is that interaction between academics, the research and demonstration farm network, and a wide range of agricultural professionals which has given the SIP its strength.  The foundation is laid.  There is now some building to do.

Monday, 4 September 2017

Multiple resources and a common vision

The Welland Valley Partnership was one of the first to be set up under Defra's Catchment Based Approach (CaBA) initiative in 2013.  The partnership is led by the Welland Rivers Trust with support from the Environment Agency, and also includes local authorities, National Farmers Union, Anglian Water and others, including ourselves.  The partnership's Resource Protection Group (RPG) includes these and other interests and aims to identify common ground between the often disperate interests of the partners and to guide and support local farmers to adopt management practices that improve the river.

But the Resource Protection Group is not concerned only with water as a resource. Soil, nutrients, and even pesticides which cause problems in water are also resources that require stewardship and wise use in order to achieve profitable farm businesses, as well as improved water quality and enhanced aquatic biodiversity.  The common ground is not hard to find.  Achieving common objectives is more challenging.

That is where the other resource comes into play - knowledge.  That includes the scientific knowledge that the Allerton Project accumulates by conducting research at field, farm and landscape scales, but it also includes the knowledge that farmers have about their land at a similar range of scales. 

Within the Welland RPG there is a balance between practical and academic expertise, spread across the spheres of water policy, catchment ecology, drinking water supply, agri-environmental advice delivery, soil science, agronomy, agricultural policy and practical farming. We have not fallen out yet!  That is not to say that we duck the difficult issues where conflicting interests create challenges, but there is a genuine desire to concentrate on the benefits to us all by focusing on the synergies between land and water management that will meet the needs of our children in future, as well as ourselves right now.

We don't have all the answers, and not everything we do goes as we might expect it to, but that is the nature of a pioneering initiative.  By working closely with the local farming community, and drawing on the latest results from our research, and all the expertise within the group, we are well placed to achieve those common objectives.  And through the Allerton Project's ongoing programme of knowledge exchange activities, we can share the lessons learnt, the good and the bad, with land and water managers from across the country so that the benefits of our work reach far beyond the river Welland.

Monday, 24 July 2017

The nature of landscapes

The wildlife present in any given landscape is determined by the characteristics of that landscape, but what are the characteristics that are most influential, especially for farmland species where the conflict between profitable food production and wildife conservation has played out most forcefully over the past half century or so?  These influences could be types of crops or the amount of semi-natural habitats, or the diversity of different crops and semi-natural habitats, or the complexity of the spatial arrangement of those crops and semi-natural habitats across the landscape.   Inevitably, different species are dependent on cropped or semi-natural habitats to differing extents, but the diversity or spatial arrangement may play an additional role.

Landscape diversity (left) and complexity (right)
We know that some bird species are associated with woodland, others with open fields, and still more use a combination of open fields and woodland or hedges.  Our monitoring at Loddington also tells us that different bird species are associated with different crops, with linnets and reed buntings using oilseed rape, and tree sparrows using field beans for example.  How crops are managed is another influence.  Low input crops support a greater abundance of invertebrate food for breeding birds than intensively managed crops for example. Twenty years ago, our research at Loddington showed that yellowhammers gathering food for their young used different crops at different times during the breeding season.  They had a foraging range of up to 300 metres, so both crop diversity and spatial arrangement of habitats would influence their access to suitable foraging sites.  
Fallow land with Holm Oaks in the study area
In a recently published paper, we explored the influences of landscape characteristics on bird communities in an agricultural area of southern Portugal.  Modelling used bird survey data from 1995-1997, and a subsequent period (2010-2012) in which changes to landscape characteristics had occurred as a result of Common Agricultural Policy reform.  For both farmland species, and rarer species that are characteristic of open steppe conditions, the heterogeneity of natural habitats had some positive influence, and for farmland species, the amount of edge had a positive effect.  However, for the steppe birds, the greatest positive influence was the area of rain-fed arable crops and pasture.

These results suggest that, while structural characteristics of the landscape have an influence on breeding bird communities, the land that is used for food production can have a greater influence for some species if managed sympathetically.   Southern Portugal is not the same as the UK, but this paper supports the suggestion that we need to consider both the composition of the landscape - the crops we grow and the way we grow them - as well as landscape heterogeneity to meet the needs of farmland wildlife. 

This is an approach that we are taking at Loddington, where we have increased habitat diversity and complexity by introducing new habitats through our Environmental Stewardship agreement, but have also increased the diversity of cropped land by extending the arable rotation to include more crops.  To some extent this change is driven by the need to manage competetive grass weeds, but this approach makes the practical management of the rotation more complicated, demands a greater knowledge base, and requires greater storage capacity for the different harvested crops for example. In the past, we have increased the complexity of the spatial crop distribution across the farm, as well as the diversity, but this proved to be a step too far in terms of the economic cost to the business.

We also modify the management of our crops, not least by the selective use of pesticides to minimise negative ecological impacts on pollinating insects, invertebrate predators of crop pests, and the invertebrates that provide food for farmland birds.  Such an approach also requires commitment and knowledge and complicates farm management decisions in what is already an economically challenging world.  The global market for crops pays little heed to the requirements of wildlife, or farmers wishing to conserve it.  Similarly, our move, over a number of years, towards a no-till system of crop establishment, stabilises soil conditions, contributing to better soil function, with potential benefits to terrestrial and aquatic wildlife, but it is not without its challenges and economic costs along the way.

Modifying crop management, increasing crop diversity, and increasing landscape complexity are all changes that are likely to benefit wildlife and landscape in the UK as much as in southern Portugal, but the farming systems and approaches to achieve this are very different.  That is something to consider between now and March 2019.