Tag: nitrogen

Efficient use of nitrogen on farm

In the face of rising fertiliser prices and environmental concerns, it is crucial to optimise nitrogen use efficiency, NUE, in agriculture. Nitrogen is a key nutrient for crop growth, but on average, only 60% of applied nitrogen is effectively used, while the remaining 40% is lost to the wider environment. This leads to both economic loss and adverse environmental impacts, such as loss of plant ecosystem diversity and waterway contamination.

Reducing reliance on the use of artificial (fossil fuel based) fertilisers is one of the key ways in which all farmers can reduce their farm carbon footprint. Hence finding ways to improve NUE is critical.

How do we go about improving our use of artificial inputs?

1.Improving fertiliser management

The first step in fertiliser management is working out the requirements. Oversupply of nitrogen has many unintended negative consequences:

  1. Reduces soil pH 
  2. Reduces soil  organic matter 
  3. Reduces soil health
  4. Increases nitrogen leaching, run off and volatilisation. 

Fertiliser uptake is most efficient when the right quantity is supplied at the right time , i.e. when the crop can take it up. Regular soil testing and analysis can provide an accurate picture of the chemical composition, providing soil indices for P, K and Mg in line with RB209 and  soil pH. The results from soil testing will be dependent on the legacy effect of previous crops, management and soil type. Standard soil testing does not measure nitrogen content. 

Soil nitrogen supply (SNS) index is used to describe the levels of available nitrogen in the soil. Through measuring the quantity of available nitrogen within the soil, the suggested nitrogen requirement from artificial fertiliser may be reduced due to the supply from the soil alone. Different crops have different nitrogen requirements which are outlined in RB209 with respect to the SNS. These tools can be used to calculate the economic optimum for fertiliser application on each crop. Alongside  fertilisers, optimising pH is critical for most crops to make best use of any fertiliser applied – for most crops it is pH  6.0 – 6.5. Agronomists or FACTS qualified advisors are a good source of fertiliser information and advice.

Timeliness of applications is also an important consideration with split applications being the best way to target the most significant growth periods. Applying nitrogen to a growing crop reduces losses as uptake is at its maximum. With the cost of applications there is an optimum balance for the number of applications on the crop.

Weather is perhaps the biggest determinant of when fertiliser can be applied. The target conditions for soil applied fertiliser are a cool temperature with moist soil. Climate change is becoming a growing threat with more extreme and unpredictable conditions becoming more regular.

Tools to measure Nitrogen

  • Soil Mineral N testing in Autumn or Spring measures plant available nitrogen allowing the grower to adjust the rate of applied nitrogen. This should be done per field and soil type across each field. 
  • Chlorophyll N Tester can be used every 7 – 10 days in most crop types once full leaf ground cover is achieved. e.g. Yara N – Tester
  • Chlorophyll N Sensor mounted on the tractor roof is linked to a variable rate fertiliser spreader or sprayer. Trials have shown a saving of 50 kg of N on wheat is possible.
  • Sap or leaf testing can also be used to measure N in a growing crop.
  • Testing grain and straw for cereals for N and S will allow an accurate budget for N removed and whether there is adequate sulphur which is essential for efficient uptake of N, it will also tell you if you have put too much/enough N on the tested crop.
  • Satellite Imagery, NDVI, can show areas of high and low biomass across fields.

2.       Nutrient management in rotation

The use of cover crops or catch crops can scavenge residual soil nitrogen when sowed after harvest. Nitrogen will be utilised by the plants and stored within the crop until it breaks down and is reincorporated into the soil. These can be used to benefit the following crop by reducing the availability of nitrates to be leached and instead making them available as the residues are broken down. Crops can also be drilled into a standing cover or sown as an understory. This can be particularly beneficial with clover which fixes nitrogen further reducing the demand for artificial nitrogen.

Cover crops are a tool within the wider crop rotation which can be designed with greater diversity incorporating legumes and deeper rooting species to improve the soil structure and residual soil nutrients. By staggering crops with a high nitrogen requirement in a rotation the SNS can be maintained thereby reducing the artificial fertiliser requirements.

Introducing a legume crop into the rotation will facilitate the fixation of nitrogen into the soil which is available for a following crop and will also support improvements in soil health.

3.       Fertiliser application

The method of application significantly influences the distribution and subsequent uptake efficiency of synthetic fertilisers. In the context of solid fertilisers, broadcasting is commonly employed, ensuring a uniform spread across the entire field. This approach is suitable for crops with dense canopies. Other methods for solid fertiliser application encompass placement, band placement, and pellet application. Employing more precise fertiliser application techniques enhances the ability to effectively target the root zone, optimising nutrient uptake but may come at added complexity and cost. When it comes to applications it is important to calibrate the spreader for each product used to ensure accuracy and reduce wastage.

An alternative to solid fertilisers which has experienced a resurgence in recent years, is foliar applications. This approach offers several distinct advantages over traditional solid fertilisers. Foremost among these benefits is enhanced efficiency, largely attributed to the rapid uptake time of products like dissolved urea, which can be absorbed in as little as 5 hours. This improved uptake time provides an additional advantage for alleviating deficiencies in a shorter time period with more flexible and tailored nutrient doses at the correct stage of growth. Additionally, by targeting the plant’s leaves rather than the soil, there is a reduced risk of soil acidification, along with diminished release of volatile compounds. This fosters a more favourable environment for soil biology to thrive and function effectively.

4.       Improving the soil

Soil is a vital component of plant growth and has a huge capacity to improve nitrogen use efficiency through improving the physical and biological components in the soil. A healthy soil is one which promotes plant health and vigour with greater resistance to stress. Healthy soils are more resilient to extreme weather conditions, better able to retain more moisture during droughts and hold more water in periods of high rainfall, thereby reducing waterlogging. Not only does this reduce leaching but it also allows for better uptake of nutrients, including nitrogen, as the soil is coping with a wider range of weather without stressing the crops.

Improving soil conditions facilitates greater biological and fungal activity which improves nutrient cycling, and through interactions with the root zone an enhanced consumption and release of essential minerals.

Increased soil organic matter levels are an indicator of a well functioning soil. Indeed this helps to promote a better soil structure and water holding capacity but it is also a crucial energy source for the microorganisms responsible for nitrogen cycling. The integration of organic manures and composts, where feasible, can significantly augment soil functionality and performance.

To conclude

  • To enhance nitrogen use efficiency, optimal soil conditions are critical. 
  • Ensure any fertilisers are delivered in the right amount, at the right time. 
  • Soil deficiencies should be minimised through sampling and proper nutrient management to allow for maximum uptake of nitrogen. 
  • Consider the use of foliar fertiliser applications to increase NUE at full crop canopy.

This blog was written by Stefan Marks, one of our Farm Carbon and Soils Advisors, to read about our team head here.

Our latest upgrade to the Farm Carbon Calculator

Today the Farm Carbon Calculator has gone live with a major upgrade. As part of our development cycle, every few months we deliver updates to ensure our calculator keeps up with the latest science, while also improving its features and usability. As the number of users continues to rise, we  regularly  update the tool to ensure it’s the best it can be and matches our users’ expectations.

The recent COP26 exemplified how carbon has shot up the agenda for everyone in societies across the world, and this fact is reflected in the number of farmers and growers we are engaging with at the Farm Carbon Toolkit. We have been advocating for over ten years that farmers and growers have a key role in cutting emissions and indeed in sequestering carbon in their biomass and soils, and we provide solutions for users to measure and manage carbon in their businesses. 

Farms are one of just two industrial sectors that can not just reduce emissions but also sequester carbon (the other being forestry). This means farming can play a positive role in the climate crisis by potentially drawing down atmospheric CO2 into its soils and biomass. Facing the climate crisis, we are here to support farmers and growers to make a positive contribution, as we all must do.

What’s changed

In this upgrade we have updated a wide range of emissions factors based on the latest research; including in Fuels, Livestock, Fertilisers, Crops, and Materials. This means up-to-date figures, more categories and therefore increased accuracy.

Major changes include a larger range of fertilisers, a huge range of branded sprays to choose from, a new way of recording livestock numbers – giving much more useful outputs, more animal feeds, new animal bedding section, a much greater range of bought in manures, and upgraded factors in fuels, electricity and travel.

There are new user features including an improved way of recording yields of crops, more FAQs to help you through the process, and videos to support you in filling in the Calculator.

On the Report Summary page, the emissions are now broken down into Scopes 1, 2 and 3, which makes Company Reporting easier and clearer. We’ve also separated results for carbon dioxide, methane and nitrous oxide, so users can understand which greenhouse gases make up their total carbon footprint. 

A brand new feature, and a great compliment to Carbon, is a way to measure Nitrogen. Thanks to funding from the WWF, and in conjunction with the Soil Association, our new ‘Nitrogen Module’ allows users to visualise the nitrogen flows in and out of their farm system. Nitrogen (N) inputs are built up from biological fixation, synthetic fertilisers and organic manures as well as purchased livestock and animal feeds. The N output is calculated from in-field N2O emissions as well as crops, milk and livestock sold and the N balance calculation provides an overview of the net change of Nitrogen over the year. 

The new Nitrogen Module shows overviews and details of the flows of N in and out of the farm

The process

It takes several months of work to prepare for an upgrade. We plan, prioritise, research, extract figures, build new functionality, review, then test, test and test again! 

The Calculator team is already planning the next update, which is scheduled for late February 2022. We will be working to update a raft of more emissions factors, reviewing the latest science (which is changing quite rapidly), and working on even more user features. Which all means that in another three months the Calculator will take an even bigger leap forward!

The Calculator can be used on all types of farms, including livestock, arable and horticulture

Working with consultants, larger companies and organisations

The Calculator will always be free for farmers and growers to use. But increasingly we have a new group of users who want to use the Calculator within their supply chains and as part of a consultancy service. 

For consultants advising farmers, we offer a licensing service, where they can receive training and access to the Calculator to calculate the carbon footprint of their clients, and deliver advice upon the results. For businesses and organisations managing groups of farmers and growers – such as buying groups, co-ops and larger food businesses, we offer a white label version of the Calculator. This is branded and tailored to the user, along with support from us, and a group admin function to manage and compare group users’ data.

Finding out more

We hope you find the Farm Carbon Calculator useful for your business, and take steps to reduce your carbon footprint. You can use the Toolkit for further help, advice and case studies https://farmcarbontoolkit.org.uk/toolkit

For help and advice on how to use the Calculator, visit our webpage https://calculator.farmcarbontoolkit.org.uk/ 

For information on commercial licenses and white label versions, please contact us [email protected]