20 May 2021

 

Dr David Cutress: IBERS, Aberystwyth University.

 

  • Sustainable agriculture looks to maintain production whilst reducing detrimental outputs but can mean different things to different people
  • For agriculture to be sustainable it must balance economic, social and environmental considerations
  • There is an increasing need and focus towards defining sustainable metrics and how these are measured so that policy and legislation practices can be put in place

 

What is sustainable agriculture

Sustainability and sustainable development are concepts that are undergoing increasing consideration across sectors globally and the agricultural sector is no exception to this. Though the term can have different meanings dependant on context, the most common definition of sustainability with regards to agriculture and food production involves meeting the needs of the present without compromising the ability of future generations to meet future needs (essentially balancing resilience with persistence). However, it can be difficult to model and define what compromises the ability of future generations, as such, many consider any practice which maintains yields whilst providing increased environmental benefits and goods to be sustainable (although with an ever-growing population simply maintaining yields is insufficient). Whilst this definition highlights production and environmental impacts, most systems revolve around the “triple bottom line” (TBL) principle which refers to equal consideration being given to (1) the environmental (2) the economy and (3) social aspects of agriculture. Sustainability is of increasing importance due to its association with environmental health as current evidence suggests that the Earth is moving towards a climate change tipping point, with agriculture having a huge environmental footprint. As such, to not “compromise the ability of future generations” sustainable systems must move towards changes which, at minimum, prevent any further environmental damage, or ideally, begin to reverse damages actively. Whilst practical on-farm impacts of environmental changes (such as increased average temperatures) may be beneficial in some situations, continued changes will likely lead to landscapes unsupportive of future agri-food production (droughts/floods and other extremes). Alongside these aspects, the increasing awareness of the finite nature of resources at our disposal comes into play, examples include phosphate rock reserves, the biological capability of our ecosystems and water suitable for plant and animal applications. Despite agriculture’s current impacts, as a sector, it is uniquely placed to offer sustainable changes that could positively mitigate much of its own environmental impacts as well as, potentially, impacts from other sectors.

 

Sustainable metrics

As noted above sustainability considers three core areas and as such the metrics collected should reflect all of these. Whilst various metrics can and have been argued to play a role in understanding sustainability in agriculture one current perspective for the UK’s agriculture sustainability may revolve around scoring the balance and interaction across the ten areas in the chart below. DEFRA is known to be considering such metric scoring systems in collaboration with the Sustainable Food Trust with the potential to incorporate them into the aims of the ‘Environmental Land Management’ (ELM) scheme.

Example scoring system for sustainable metrics based on Sustainable Food Trust resources where 10 areas are scored and given minimum requirements and thresholds which lead to increased subsidies–Above Farm 1 fails to meet minimums in social capital, biodiversity, water, livestock management and crop health. Based on key metrics converted to an arbitrary scoring system

 

Productivity is a common metric in agriculture as it is a key driver for profitability and developing and improving performance. When considering sustainability, different metrics can provide a different story. For example, comparing the total production of methane (CH4) between farming systems can indicate one system is better than the other, but assessing the CH4 output per kg of product or kg of protein can demonstrate a different sustainability story.

Human capital includes employment opportunities and the ease of access and assistance in providing economically viable skills to individuals in the industry and future generations. As such, metrics should factor in training and apprenticeship programmes to facilitate continued education and innovation opportunities. Skills that may become increasingly of value in agriculture include sales and business understanding, marketing knowledge and information communication technologies (ICT) skills. This area also includes grower/farmer safety and wellbeing considerations.

Social capital looks to evaluate the social benefits associated with agricultural practices and the forming of, and benefiting from, diverse social groups with a focus on values, trust and cooperation between groups involved. This can include providing social spaces and other public goods within agricultural land for the general public to enjoy improving mental health and wellbeing for example but many aspects are difficult to observe and assess.

Biodiversity is known to be influenced by multiple agricultural practices in both positive and negative ways. As we move towards a perspective of considering ecosystem/environmental services determining metrics for biodiversity are increasingly important as local flora and fauna contribute to these areas hugely.

Soil, nutrient management, and resource efficiency with regards to sustainability can be interlinked in many ways. Soil structure and properties are a key aspect of sustainable measurement metrics as these are vital for assessing the ability of crops, pastures and forests to grow effectively without overusing available resources (where integrated nutrient management comes into play) or polluting or damaging the surrounding ecosystem. Vitally, soils also offer a huge area for environmental improvement by having the capacity to sequester carbon and play roles in nutrient cycling pathways, thus they impact significantly on greenhouse gas (GHG) emissions.

Water is often considered the most critical resource for sustainability worldwide and includes considerations for utilisation as a resource (via irrigation, for example) as well as agricultural impacts on watercourses via blocking, diversion, flood mitigation and pollutant input. Several aspects can have a knock-on impact on social capital aspects as well as biodiversity.

Energy and resource efficiency includes fertiliser use and soil nutrients availability as noted above as well as fossil fuel use and alternative power sources with regards to minimising detrimental factors such as greenhouse gas emissions. It also leads towards minimising the use of non-renewable inputs into systems which lead to unsustainable long-term resource efficiencies.

Sustainable livestock management generally assesses strategies to reduce GHG outputs associated with livestock to improve long-term sustainability whilst balancing continued performance and welfare of systems to ensure profitability. Particularly as certain livestock management routines can have beneficial impacts on biodiversity, plant and crop health and soil/water health and function.

Sustainability in crop and plant health includes breeding resilience to changing environments and challenges such as pests and disease. Sustainable systems look to build in redundancies where for example, crop mixes are used that include species or varieties that offer variable levels of tolerance to environmental extremes such as flooding or drought. This moves away from mono-species systems and offers potential to targeted breeding or genetic modification to improve systems for long term sustainable applications. Other practices which fall into this area include integrated/biological pest control and reduction of damaging chemicals.

 

Measuring sustainability

Whilst defining key metrics of interest to the UK agricultural sector are underway, how these can be effectively measured is another consideration entirely. Certain areas have a history of assessment via the basic payment and other grant schemes, however, new focuses and targets including carbon soil levels and GHG emissions make accurate assessments increasingly complicated. In monitoring and incentivising future agricultural sustainability, there is likely to need to be a balance struck between using accurate measurements and less accurate prediction models. Several technologies for measuring metrics accurately are extremely sensitive (and don’t work in the field well) or are very costly and as such are generally used to develop a set of defined ranges or to assess proxy measurements in experimental scenarios. These metric ranges and proxies can then be performed in the field via reduced accuracy methods. This also has to be balanced with issues surrounding the variability found across agricultural systems as well as external variables (including annual weather patterns), which in an ideal world would mean metrics were assessed on a case by case basis, however, this is rarely feasible both functionally and economically with current technologies. An example can be seen in a recent study that found that soil measurements affected least by variability were pH, soil moisture and bulk density, but many of the carbon and nitrogen assessments were still variable at normal sampling levels. Variability reduced with 10 - 60 more samples per area but this adds cost, labour and complexity when upscaling UK wide results. Finally, many sustainable outcomes take a significant amount of time for results to be observed making it challenging for farmers to see benefits that encourage the maintained use of practices in the short term. Below a selection of the current and potential metrics and assessment techniques are noted, there is rarely a single assessment measurement available for any metric, thus adding to the variability and accuracy levels achievable particularly when comparing for benchmarking between methodologies.

Metric

Assessment methods

Metric

Assessment methods

Plant health

Spectral tools from drones or satellites - normalized difference vegetation index  (NDVI), near infra-red (NIR), visible red, green, blue spectrum (RGB)

Water quality

pH, conductivity, dissolved oxygen levels, optical sensors, turbidity, flowmeters, chromatography, spectrometry

Predictive models

Productivity

Farmer records (yields vs inputs)

Radar tools for drones or satellites (LiDAR etc) - Plant moisture, forest biomass 

Automated calculations through farm manager software

Soil moisture

Spectral tools from drones or satellites (NDVI, near infra-red (NIR), RGB)

Drone or satellite visual tools for crops and pasture yields

Moisture meters (handheld or part of remote precision systems) can be tensiometers or granular matrix sensors

Precision weighing tools (livestock)

Electrical conductivity mapping

Imaging tools for livestock growth

Radar tools for drones or satellites (LiDAR)

Automated feeder and milking data (livestock)

Calcium carbide method

Predictive models

Oven drying

Radar tools for drones or satellites (LiDAR) -  e.g. crop growths analysis

Soil health

 

 

Proxies (including; bacteria/fungi ratios, Glomalin content)

GHG emissions

Predictive models

Spectral analysis of macronutrients

Chamber techniques (doesn't always mean an actual chamber - can include for example facemasks making a "chamber" around the animal’s face or other enclosed spaces)

Soil conductivity

Soil strategic sampling

Proxies (including; sulphur hexafluoride tracer, milk mid-infrared spectroscopy (dairy), microbiome profiling)

K and P soil

Chemical extraction and sorption methods

Human capital

Surveys

Spectrophotometry

Farm safety assessments

N soil

 

 

Chemical extraction and sorption methods

Assurance schemes (Red Tractor has criteria for human and food safety concerns for example)

Spectrophotometry

Social capital

Surveys

Combustion techniques

Air quality

Spectrometry (for example tunable diode laser techniques)

Proxies (Soil microbiome enzyme activities)

Chamber techniques

pH Soil

 

pH meters (glass/calomel electrode system)

Biodiversity

Countryside survey

Proxies (vegetation species composition, microbiome enzyme activities )

Farmland bird index

Soil carbon

 

 

 

Combustion techniques

Land cover map

Acid treatments

Drone or satellite remote sensing analysis developments

Walkley black test

Reporting systems [1]

Proxies (permanganate oxidizable carbon, microbiome enzyme activities)

Reporting systems[2]

Remote sensing tools (low accuracy still in development)

Radar tools for drones or satellites (LiDAR)

Notes:

  • In most instances, grower observation can also play a role but are considered variable due to their subjective nature
  • Where tools are noted for drones and satellites these can also be handheld or vehicle-mounted for assessing fewer plants at a time but more accurately
  • Soil metrics and assessments can largely be adapted for analysis of organic fertilisers for sustainable applications
  • Most metrics have some form of predictive model associated despite only a handful being noted above

 

 

Despite complications surrounding setting accurate sustainable metric ranges, having some form of a range and minimum requirements for growers to work to is better than nothing. Many measurements are based on mathematical models influenced by previous research and as such have varying levels of accuracy and robustness. Examples of such include the new pollution legislation for Wales where animal manure nutrient/pollutant contents are calculated based on averages. Whilst a useful tool in general this could lead to variation where farmers supply livestock with new or experimental feed sources, use processing techniques on their organic fertiliser or utilise diverse animal breeds for example.

 

Sustainable drive in agriculture

Many of the discussed sustainable elements fall into the public goods financial assistance areas of the Agriculture Act 2020 and the Wales ‘Agricultural Bill’ and are as such a current focus. The future ELM scheme which will replace direct payments within England also has a clear focus on reducing emissions, improving environments and increasing human and animal welfare with similar scheme development ongoing in Wales. All of this demonstrates a commitment to sustainable agriculture moving forwards. Equally, with carbon taxation and trade scheme discussions ongoing in an attempt to balance the ‘carrot and stick’ approach to meeting UK net-zero targets, sustainable farming systems will become increasingly attractive. Defining sustainable metrics in future could be vital to farm profitability if moves towards carbon taxes on high GHG emitting products such as meat, milk and cheese come into place. Systems considered stable and sustainable might increasingly benefit from the value of carbon credit as is being demonstrated by land use for tree plantation. It is also important to consider other debates surrounding sustainability strategies. One consideration heavily discussed is the need for a change in consumer habits to achieve a truly sustainable system. With currently around a third of all food wasted worldwide and an imbalance between richer countries over-consuming whilst poorer countries under-consume, this aspect needs increased attention to improve overall agri-food supply sustainability. Furthermore, arguments exist that environmental stability in agriculture requires a change in consumption habits towards reduced animal protein products. Whilst these discussions are highly complex to unpack they will likely increasingly factor into long-term sustainability considerations within the agricultural sector.

 

Summary

Sustainability is a highly complex concept within agriculture and can differ based on the perspective of those involved. Improving environmental benefits in one farm/country/sector might seem sustainable in isolation but could be detrimental when considering yield losses or knock-on changes in surrounding environments on a global holistic scale. As such there are likely to be many pathways towards achieving agricultural sustainability with different solutions in different situations. To facilitate this having a defined set of sustainable metrics which function both at individual levels and holistically are vital and should be a key focus as new sustainable perspectives are developed. Confusion often arises which could obscure the concepts of sustainable agriculture at the farm-level up to policy level as there are many alternative ‘options’ surrounding the same theme each with their advocate groups (such as regenerative agriculture, agroecology, permaculture, resilient farming, circular economy and bioeconomy). As such it is important that the essence of why these concepts exist (to reduce detrimental human impact whilst maintaining our ability to thrive) be the focus rather than the system itself. Whilst not covered in this article, many practices exist which could be employed by growers to improve their sustainability. Several of these have been highlighted by the Farming Connect Knowledge Exchange hub and a selection of articles can be found below;

Legume use, manure management and ammonia emissions , livestock management for ammonia emissions, poultry emission mitigations, upland sustainability, nanoparticle applications, biochar, pig specific manure management, water management on farms, carbon capture techniques and species rich grasslands

 


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