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Cover crops: the route to sustainable farming?

Given the increasing focus on soil health, erosion, and pollution, as a result of current agricultural practice, cover cropping is now being used across all sectors of crop production to save nitrogen and agrochemical inputs, increase yields and boost soil sustainability. Is cover cropping the route to sustainable farming? Agri-EPI Business Development Manager Duncan Ross dives into the topic for us highlighting the benefits to farmers to embrace a cover crop farm strategy:

Cover cropping means different things to different people, and the reasons for adoption of cover crops into a farming regime are very diverse and often specific to a particular farm. The transition from Common Agricultural Policy (CAP) as a support mechanism for agriculture to one based on environment and soil management (DEFRA’s Agricultural Transition Plan) will no doubt encourage wider uptake of cover crops.

Cover crops are often referred to as over-wintered, fast growing annuals planted between two cash crops. However, in certain circumstances a cover crop could be considered to cover a complete 12-month cycle due to geographical location, or a short-term grass ley.

The benefits can be many, such as:

  • Increasing levels of soil organic matter, as green manure is incorporated into the soil. increasing biological activity and water retention capacity.
  • Capture of vital nutrients that are made available to the subsequent cash crops rather than lost due to leaching.
  • Improve soil structure as vigorous root activity can be used to break up compaction.
  • Reduce pollution of nutrient and pesticides into water courses and erosion of soil.
  • Habitat creation which can be included in agri-environment schemes to generate additional revenue and can improve pest management by encouraging beneficial insects.

Healthier cropping sequences on the farm

Financially, it may be difficult to quantify the benefit, as any potential reduction of inputs or increase in yield of the following crops are offset by the cost of establishment and destruction of the cover crop. Cover crops, though, should be treated as an integral part of the rotation and good establishment is imperative, drill rather than broadcast, small nitrogen and slug pellet applications will result in a higher level of biomass, more nutrients being captured, more root activity, less pollution/erosion.

Which cover crop should I use?

The correct choice of cover crop will vary from farm to farm and will be dependent on many variables such as: what is trying to be achieved? Things to consider would be:

  • Soil type
  • Geographical location – less likely to get good autumn establishment in Northern parts of the UK.
  • Rotation – not using brassicas in a rotation containing OSR
  • Sowing dates – sooner after harvest of previous cash crop as practical to maximise biomass potential
  • Following plant timings – not to compromise future cash crop
  • Previous herbicide usage – residual herbicide could affect cover crop

Farm Business strategy

Seeking expert agronomic advice is key in making the correct decisions on cover crop strategy and type of seed to be included within the mix. For example, if the aim is the long-term management of arable weeds, where there are fewer active ingredients available, and herbicide resistance is to be considered, the weed challenge must be managed across the whole rotation. The cover crop chosen should be established and then destroyed along with the target weeds before it is able to re-seed, and over time the seed bank can be reduced. This method would rely on use of glyphosate as a control method so as not to disturb the soil as deep cultivation would mix the soil profile and reduce the effectiveness of the strategy.

Putting this into practice, some growers are having success with crimper rollers to destroy the cover crop and do away with the use of chemical control and should glyphosate be banned this may be the best option for conventional no-till farmers.

Measuring soil flux as a way to understand GHG emissions from soil

Meeting the challenge of climate change with soil flux analysis

For growers, agri-chemical companies, producers and food retailers monitoring and measuring positive and negative soil flux can help balance greater productivity, sustainability and improved soil health. What is soil flux analysis and what impact does it have on climate change?

Driving net zero reduction

Global Green House Gas emissions are a sensitive topic politically with international agreements of targets and the drive to a net zero status, but there is a debate going on also about who is the most culpable.

GHG emissions - IPCC 2014 | Soil Flux Analysis | Agri-EPI blog | Soil and Crop Technology Solutions

Carbon Dioxide (CO2) is by far the highest proportion of GHG emissions at around 75%, but Methane (CH4) and Nitrogen Oxide (N2O), although less in proportion, are respectively 28 times and 310 times more potent than CO2. Most of these emissions come from the burning of fossil fuels for energy production, transportation, manufacturing and building but land use also plays a significant part.

In 1973, the National Soil Inventory (England and Wales) was set to obtain an unbiased estimate of soils, and their carbon content. Since the original survey, further sampling has shown that in most soil types, there has been a progressive decline in carbon content, and the inference is that other temperate regions would show similar traits.

Losses due to land use activity

Inefficient use of fertilisers results in N2O being last as emissions to the atmosphere, and nitrates being leached through the soil into water courses. By targeting applications more effectively to ensure the crop is only given what it can utilise we are able to reduce these losses. Using variable rate applications, or slow release Urea are examples of how land managers are changing behaviour.

Storage and application of slurry and manure also result in emissions. Covered stores, better timing of applications and use of dribble bars and direct injection of slurry rather than splash plates can all contribute.

Rumination results in emissions of CH4 which give cattle and sheep a particularly bad image. This is more a factor in international production than UK, where many animals graze pasture unsuitable for crop production, and that permanent grassland can also be considered a net carbon sink.

Deforestation for agriculture, although not an issue in the UK, but certainly in other parts of the globe for production of soya and palm oil amongst other commodities has a significant impact. We not only lose the of that forest to act as a carbon sink, but the felled and cleared timber both emits CO2 and subjects the cleared areas to the potential of erosion.

Cultivations result in emissions from varied sources, the tractor exhaust (combatted in recent years by addition of EGR and AdBlu technology). The soil surface, as each cultivation releases naturally occurring gases into the lower atmosphere (minimum tillage and direct drilling have had some impact by reducing the amount of soil disturbance)

Natural ecological processes in the soil sub-surface produce and consume gases, and as the soils warm due to climate change, microbial metabolic rates increase resulting in increased CO2 emissions. Gases diffused from the soil surface into the lower atmosphere is known as positive flux, and gases absorbed into the soil is known as negative flux, the balance between the two will determine whether soils are a net source, or a net sink of GHG.

Soil Flux chambers

To calculate this, we need to collect accurate data on soil respiration rates, which can be done by using soil flux chambers. There are several different manufacturers of soil flux chambers, but they can be separated into two main categories.

  1. Closed chambers where the gases accumulate in the headspace and are sampled by syringe and stored for laboratory processing and analysis.
    • PP Systems CPY-5 Canopy Assimilation Chamber (#1)
  2. Automated chambers which can provide a timely method of sampling, as when coupled with a multiplexer and an analyser, up to 12 chambers can be linked in series and be deployed over a long period to sample and analyse in the field (subject to a reliable power supply)
    • Eosense eosAC Automated Chamber (#2)
    • Eosense Multiplexer (#3)
    • Picarro G2508 for analysis of CO2, CH4, N2O, NH3, H2O (#4)
    • Picarro G2201-i for analysis of CO2, CH4 and their C13 isotopes (#5)

 

Soil Flux Analysis | Agri-EPI blog | Soil and Crop Technology Solutions

 

All of the above equipment is designed to be used in the laboratory or the field (subject to a satisfactory and reliable electricity supply). The Picarro G2201-i (#5) is particularly useful for academic research applications, as it is more robust and user friendly than typical mass spectrometry methods (McCloskey et al 2020).

Strawberry gas flux measurement research

The time saving that can be achieved by automated chamber equipment deployed in a field experiment is demonstrated by Pamona College, California when monitoring soil flux in a commercial strawberry crop. The time in the field and the interpretation was the same using both systems, but the processing of the data represented a huge time saving for the trial, reducing the days from 68 down to 1.

Monitoring soil flux in Pamona College in California | Soil Flux Analysis | Agri-EPI blog | Soil and Crop Technology Solutions

Soil commercial and research enquiries

For further information on this equipment and the possibilities of incorporating into commercial or research studies with the Soil Flux 360 solution, please contact Duncan Ross, Business Development Manager Crops at Duncan.ross@agri-epicentre.com or fill out our online contact form.

Minimising waste with water sustainability

Water sustainability and agriculture

In recognition of water saving week, Agri-EPI Centre’s Membership and Events Manager, Annabelle Gardner, spoke with member Grant Leslie, Co-founder and Chief Operations Officer of SEM Energy, an environmentally conscious sustainability partner in waste and water effluent treatment.

SEM Energy Offices

SEM Energy Offices

What does your company do?

We are an environmentally conscious sustainability partner in waste and water effluent treatment. Our team of scientists, engineers and technologists pioneer leading-edge technologies that process co-products from ‘waste’ streams and deliver innovative water treatment solutions.

Our goal is to:

  • Reduce waste
  • Maximise solid matter capture
  • Save on haulage, storage and logistics costs
  • Increase efficiencies
  • Shrink the carbon footprint

What is your company vision?

A waste-free, circular economy in the future, securing our planet’s health and wealth for generations to come. We aim to minimise the impact of waste on the environment and, where possible, create value from its co-product waste streams and ensure compliance with discharge legislation.

Can you provide a case-study or example of the sustainable work you currently undertake in agriculture?

On-site conversion of agricultural animal slurry into organic horticulture products:

  • Aim – a reduction in slurry waste handling (Our client’s slurry production totalled 32,000 tonnes per annum.)
  • Method – using SEM technology to separate the liquid phase and de-water dry matter to create economically and socially valuable by-products
  • Results: water safe to discharge to local watercourse; solids (4% of total volume) used as fertiliser locally; 23% saving in handling, storage and transport costs.

We have been working with a client for the past year, applying our ever-evolving range of technologies and solutions to reduce the handling of slurry waste. Our aim is two-fold: effective separation of the liquid phase for treatment and re-use, and substantial de-watering of the dry matter to create an optimised, valuable by-product which can be re-purposed as livestock bedding, biofuel, fertiliser or growth media.

We implemented our patented MDM technology, which mechanically removes the liquid phase from slurries. It’s so effective that it also captures micro-solids as small as colloidal particles.

We integrated this with our I-DAF unit. An intelligent and autonomous upgrade to most DAF systems on the market today, it’s designed to maximise the removal of: total suspended solids (TSS); biochemical oxygen demand (BOD); chemical oxygen demand (COD) and heavy metals.

Sticking to our environmental guns, we used plant-based coagulant, flocculant and pH correction products that are automatically dosed, based on built in instrumentation readings. This ensured both homogenous, reliable performance and minimal chemical usage. The biodegradable formulations minimise environmental impact, whichever sludge disposal route chosen.

In order to ensure maximum nutrient capture and transfer from the liquid phase into the solids, we used another patented technology of ours – DRAM Filtration – to remove nutrients and heavy metals. DRAM utilises an organic matrix, over 99% of which is comprised of an existing and sustainable, agriculturally produced, grain-based, waste co-product from alcohol distillation.

The filtration process works through sorption, and readily sorbs ammonium nitrate and phosphorous. Combined with an additional proprietary reagent (DRAM+) which provides potassium, these form the essential fertilising elements.

Can you give an example of one of your technologies that focuses on water saving and water sustainability?

H2OPE – our flagship product for the agricultural market:

  • Removes volatile contaminants and de-waters
  • Optimises valuable ingrained nutrients
  • Remaining solid matter can be pelletised for use as fertiliser or as a nutritionally balanced growth media

The environmental benefits:

  • Reduction in application of nutrient rich liquids to agricultural land
  • Decrease in diffuse pollution of waterways due to agricultural run-off
  • Reduced carbon impact due to reduction in transport of slurries off-site
  • Significant reduction in the carbon generated by the manufacture of fertiliser

The social benefits:

  • Fewer greenhouse gases
  • Effluents can be treated on-site
  • Economic savings, as one of the by-products is steam, which can be used for on-site energy generation and distilled water.
  • Less odour emissions

Can you describe the significance of water sustainability in the agricultural industry?

Our goal is always to clean water well enough for re-use and re-purpose at source, whether that is for washdown water or perhaps irrigation. An absolute must for us, this aligns not only with our aims, but those of the United Nations 17 Sustainable Goals.

The sector has been, and will continue to be, paramount to the global economy. By protecting our ecosystems from potentially harmful co-products, we are sustaining not just the agriculture industry, but also the evolution of a circular economy.

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