Improving nutrient management will, without doubt, be one of the major planks in future funding for the industry.

In fact, it forms a major plank in the work done and recommendations put forward to ScotGov by the Suckler Beef Climate Change Group in its recently published report.

While muck and slurry is often seen as a 'dairy problem', the group acknowledged that some of the more intensive suckler beef units can also produce a lot of muck and slurry and many of the positives that it contains need better targetting.

Better use of the by-product is seen as a huge step forward in making the industry reach its goal of reducing significantly both the amount of greenhouse gases produced by beef herds and the sequestration of carbon back into the soil.

The suckler group's thinking on muck and slurry was to reduce nutrient losses to reduce the emissions intensity from their production systems by:

* Improving on-farm nutrient utilisation by better targeting nutrient inputs for an optimum crop response; * Reducing synthetic fertiliser inputs by maximising the use of slurry and farmyard manure along with alternative sources of nitrogen.

The management options being proposed should also deliver environmental benefits and help to protect the local biodiversity and soil life by reducing the risk of nutrient run-off or leaching into the surrounding ecosystem and watercourses.

An increased focus on organic and within-sward sources of nitrogen will also deliver further benefits for soil microbial life as a result of a lower reliance on synthetic fertilisers.

The main focus of any nutrient management plan typically lies with the major nutrients nitrogen (N), phosphorus (P) and potassium (K). These nutrients are expensive to purchase and, if left unused by the plant, can lead to environmental issues as a result of leaching and run-off.

Further pressures on the environment are caused by greenhouse gas emissions caused by nutrient losses into the atmosphere through volatilisation. A recent report showed that almost 50% of Scottish nitrogen applications in 2017 – the equivalent to an average of 92kg of N per ha – was not taken up by the target crop and as a result were lost to the environment.

The group assessed, therefore, it was crucial to better target nutrient inputs, reduce nutrient wastage, and take steps to avoid nutrient losses via greenhouse gas emissions.

Another recommendation was for covering slurry stores as the way slurry is collected, handled, stored and applied can greatly influence the extent to which any nutrient losses, via methane, ammonia and/or nitrous oxide emissions occur.

A large proportion of slurry associated methane and nitrous oxide emissions occur during storage and open slurry stores where the slurry has not formed a natural crust can significantly enhance the potential for greenhouse gas emissions.

According to a recent feasibility study, greenhouse gas emissions associated with slurry management contribute 7% towards total emissions from Scottish agriculture and 1.3% towards total Scottish emissions.

The same study estimated that there is a potential to reduce agricultural greenhouse gas emissions by 180,000 tonnes of CO2e per annum if slurry stores were covered in order to prevent losses of ammonia into the atmosphere – that equated to a reduction in total emissions from Scottish agriculture by 2%.

With approximately 40% of this slurry, or 2.57mt, being produced by beef cattle, there is an opportunity for suckler beef producers across Scotland to cumulatively reduce annual emissions from slurry storage by 72,000 tonnes of CO2e.

For every 100kg of slurry produced, this could potentially reduce emissions by 2.8kg and could lead to a reduction in total emissions from Scottish agriculture by 0.8%, therefore making the covering of slurry stores a major opportunity to deliver quick and significant results.

The group argued that it not only made better use of nutrients and minimises issues associated with limited slurry store capacity, but undiluted slurry results in a lesser requirement to having to handle large quantities, reducing fuel use and associated expenses in spreading it.

A case study conducted by Defra, Natural England and the Environment Agency97 found that covering a slurry store increased the farm’s storage capacity by 25% which led to savings of more than £1600 per annum.

A further study by the Silsoe Research Institute found that covering a slurry store could reduce ammonia emissions from cattle slurry by 78%, mirroring the case study conducted by Defra.

Improving organic N efficiency

Organic manures are a valuable source of on-farm nutrients and can provide a cost-effective alternative to purchased fertiliser to help boost plant growth and productivity, added the report.

Making better use of this organic fertiliser does, however, depend on accurate and regularly updated nutrient planning, timely applications and efficient application.

If N inputs are not properly targeted, significant nutrient losses may occur into the atmosphere, or into the nearby soil and water environment via volatilisation and/or leaching, the report argued.

This not only results in higher GHG emissions but can lead to environmental pollution. Poorly targeted nutrient inputs also impact on enterprise efficiency and profitability as this can lead to a greater reliance on purchased fertiliser to meet plant nutrient demands.

The group's management option aimed to encourage participants to better target manure applications in order to improve their organic N efficiency and as a result reduce greenhouse gas emissions and any associated nutrient losses.

This relied on effective nutrient planning using the known N content of the manure, as well as the type of crop that it is being used on and its specific nutritional demands at key stages of production. This information should then be used to calculate appropriate manure application rates.

Manure should also be applied in suitable weather conditions and when the crop is actively growing in order to ensure that the plants are able to properly utilise nutrient inputs at the time of application.

Better utilisation of organic N can be enhanced by replacing less accurate application equipment, such as broadcast slurry spreaders, with precision application equipment for improved targeting of organic nutrients through the likes of band-spreading, trailing shoe application or shallow injection.

Further benefits obtained from an improved utilisation of organic nutrients include improved profitability and additional greenhouse gas emissions savings as a result of a lesser reliance on manufactured synthetic fertilisers delivered to the farm from further afield.

Soil animal and microbial communities, including the extremely valuable and often under-appreciated earthworm, will also benefit from and be safe-guarded by better targeting of manures and greater organic N use.

A study showed that maximising the utilisation of N within manures, for instance by using a recognised fertiliser planning tool in conjunction with regular manure analysis, could reduce direct nitrous oxide emissions by up to 5%.

The same study confirmed that further emissions reductions can be obtained by better timing manure applications during the growing season in line with conditions and plants actively needing nutrients, in which case nitrous oxide emissions could be reduced by an additional 2% to 10%.

Low emission precision spreading equipment can furthermore reduce ammonia losses by around 60%, compared to a splash plate spreader.

Synthetic N savings of 10kg per ha can also be made through improved planning of organic N use, and again by switching to a low emission spreading system and nitrification inhibitors could lower NO emissions by up to 50%.