Real-time in situ sensing of soil nitrogen status to promote enhanced nitrogen use efficiency in agricultural systems

Lead Research Organisation: Bangor University
Department Name: Sch of Natural Sciences

Abstract

Nitrogen (N) is vital for crop productivity, however, typically half of the N we add to agricultural land is usually lost to the environment. This wastes the resource and produces threats to air, water, soil, human health and biodiversity, and generates harmful greenhouse gas (GHG) emissions. These environmental problems largely result from our inability to accurately match fertiliser inputs to crop demand in both space and time in the field. If these problems are to be overcome, we need a radical step change in current N management techniques in both arable and grassland production systems. One potential solution to this is the use of technologies that can 'sense' the amount of plant-available N present in the soil combined with sensors that can report on the N status of the crop canopy. On their own, these sensors can provide useful information on soil/crop N status to the farmer. However, they need refining if they are then to be used to inform fertiliser management decisions. This is because climate variables (e.g., temperature, rainfall, sunlight hours) and soil factors (e.g., texture, organic matter content) can have a major influence on soil processes and plant growth, independent of soil N status. These sensors therefore need to be combined with other data and improved soil-crop growth models to provide a more accurate report of how soil N relates to crop N demand at any given point in time. In this project, we are demonstrating how adoption of precision agriculture techniques (in the form of soil nitrate sensors) can be used to improve N use efficiency in both arable (wheat, oilseed rape) and grassland systems. While we are focusing on soil nitrate, as it arguably represents the key form of soil N associated with productivity and the environment, the approaches we are taking are also readily applicable to other nutrients for which sensors are currently being developed (e.g., ammonium, phosphate, potassium).

We have designed our research programme in accordance with the strategic objectives of the BBSRC-SARIC programme and those recently produced by HM Government to facilitate delivery of sustainable intensification strategies. To maximise the potential for technology development, commercialisation and adoption we are working closely with a range of industry partners throughout the programme. Overall, we aim to (i) demonstrate the use of novel N sensors for the real-time measurement of soil N status; (ii) use geo-statistical methods to optimise the deployment of these in situ sensors; (iii) produce new mechanistic mathematical models which allow accurate prediction of crop N demand; (iv) validate the benefits of these sensors and models in representative grassland and arable systems from a N use and economic standpoint; and (v) explore how these new technologies can improve current fertiliser management and guidelines through enhanced industry-focused decision support tools.
Ultimately, this technology shift could result in substantial savings to the farmer by both reducing costs, maximising yields and minimising damage to the environment. For example, if our technology improves N use efficiency by 10% in agricultural land where fertiliser is applied in the UK (8.2 million hectares of grassland and tilled crops), we estimate it would save 100 thousand tons of N fertiliser (equivalent to a saving of £69 million per annum to farmers). When the direct and indirect costs of nitrate pollution are considered (e.g., removing nitrate from drinking water is estimated to cost UK water companies >£20 million annually), and the reduction in direct and indirect greenhouse gas emissions from manufacture and use of 100 thousand tons of N fertiliser are accounted for, the benefits of adopting a validated precision agriculture approach are clear.

Technical Summary

The inefficient use of nitrogen (N) within agricultural systems is almost ubiquitous with typically only 50% of the N applied to the land subsequently recovered in the crop. This gross inefficiency is largely caused by the poor spatial and temporal targeting of fertiliser N relative to crop N demand, leading to a major loss of N to freshwater, groundwater and the atmosphere (via leaching, surface runoff or gaseous emissions). This diffuse pollution has a major environmental impact as well as a producing significant social (including human health) and indirect economic cost. One of the biggest challenges facing the agricultural industry is therefore finding new ways to optimise the use of N fertiliser to both reduce costs and improve sustainability. In response to this challenge, and in direct alignment with both the strategic objectives of the SARIC programme and those of RCUK (2016), we describe a new integrated precision agriculture approach to achieve this goal. Our aim is to combine the power of new soil-based in situ N sensors with mathematical models, spatial statistics and existing canopy N sensors to develop new decision support tools to allow farmers and their advisors to decide when and where to apply N. A range of key industry partners have joined this project consortium to demonstrate how soil and canopy sensors can be deployed in arable and grassland systems for measurement of soil and crop N status. Geo-statistical methods will be used to show the optimal deployment of these sensors. This information will feed into new mechanistic models which will be used to predict crop N demand. Together with our industry partners, we will explore via workshops and outreach activities how these new technologies can improve current fertiliser management and guidelines through enhanced industry-focused decision support tools.

RCUK (2016) A vision and high-level strategy for UK animal and plant health research to 2020 and beyond. BBSRC, ESRC, NERC, HM Government.

Planned Impact

UK agriculture uses over 0.85 million tonnes of nitrogen (N) fertiliser each year which is spread over 8.2 million hectares of tilled and grassland soil. A major proportion of this added fertiliser, however, is not taken up by the crop and is lost to the wider environment. This results in a major economic loss to farmers and can lead to pollution of water courses, groundwater and the atmosphere. As the use of synthetic fertilisers will continue to be pivotal in food production for the foreseeable future, new ways are needed to effectively target the efficient use of this resource. One of the major outputs from our research programme will be the development of new decision support tools that utilise on-farm, real-time soil data which continually update during the growing season. This represents a major advancement in current fertiliser guidance systems (e.g. RB209, Planet, Farmscoper). The outputs of our research on society can be grouped as follows:

INDUSTRY: This research proposal is directly underpinned by key industry partners. These include (i) Yara UK who are one of the leading suppliers of N fertilisers, crop nutrient sensors (e.g. Yara-N-Sensor) and fertiliser guidance; (ii) Agricultural Industries Confederation (AIC) who are the agrisupply industry's leading trade association. AIC's Fertiliser Sector represents over 95% of the UK's agricultural fertiliser supply industry, worth about £2bn; (iii) British Grassland Society is a communication forum which through events and publications promotes the profitable and sustainable use of grass and forage; (iv) Agriculture and Horticulture Development Board (AHDB) is a Levy Board which represents the cattle, sheep, pigs, milk, potatoes, cereals, oilseeds and horticultural industries. AHDB are also responsible for reviewing current UK fertiliser recommendations associated with RB209; (v) Delta-T Devices are one of the leading companies in the development and sales of soil and plant based sensors; (vi) Syngenta is one of the world's leading agricultural companies with an annual global revenue of £l0 billion; (vii) AgSpace are leading software developers producing decision support tools for precision agriculture. Our project directly aligns with the strategic priorities for all these industry organisations. All the main partners will be members of our management board, and will provide invaluable guidance throughout the project and will facilitate the dissemination of the project findings.

POLICY COMMUNITY: The results from this project will directly inform policymakers (e.g. Defra, DECC) by providing clear advice on future developments in precision agriculture including the environmental and economic costs and benefits and barriers to technology adoption. We will also provide guidance on the timelines and likely impact that adopting these technologies will have at the UK level and its potential impact on the UK N inventory. Policymakers are also central to our proposal (see WP5) ensuring dialogue throughout the programme. We will also build on our established links with Defra and Welsh Government to ensure effective dialogue.

WIDER COMMUNITY: A web page and Twitter feed from the Bangor website will provide ongoing information on the project and its results. Different aspects of the project will be used for teaching, generating student projects, and will be presented at open days at (1) the Bangor University Agricultural Extension Farm, which is one of Defra's Sustainable Intensification Platform flagship sites, and (2) by our industrial partners. We will also feature the project in School Science Week, using visualisation of nitrogen pollution to stimulate wider discussion about agriculture and the environment. See also the section of Pathways to Impact for more details.

SCIENTIFIC COMMUNITY: Our research will inform scientists working in several areas of research (see Academic Beneficiaries section for more details).

Publications

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Carswell A (2018) Assessing the benefits and wider costs of different N fertilisers for grassland agriculture in Archives of Agronomy and Soil Science

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McKay Fletcher D (2021) Precipitation-optimised targeting of nitrogen fertilisers in a model maize cropping system in Science of The Total Environment

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Moreau D (2019) A plant perspective on nitrogen cycling in the rhizosphere in Functional Ecology

 
Description • We have developed a simple, low-cost, field embeddable, a new type of sensors fitted with NO3- ion-selective double matrix polymeric membrane (DMPM) assembly to the conventional liquid filled electrode (N-sensor). N-sensor DMPM was designed and developed for real-time soil NO3- measurement continuously.

• Validation studies are key to assess the functionalities of N-sensors in response to crop N uptake dynamics, lining up with time scale of N-fertilization, assimilation, and transformation in agriculture soil. We have developed models for N-sensors to compensate the environmental variable which is crucial for developing field-based N-sensors. The incoming signals were converted using data compensations for a final read-outputs indicating the actual nitrate levels in real-time.

• Developed custom designed state-of- the- art Internet of Things (IoT) LoRaWAN loggers to support wireless data cloud transmission for real-time data readings from prototype soil N-sensors.

• Prototype loggers were developed. LoRaWAN can collect the field data measurements and transmits to the cloud that can cover the sensors deployed within 10 km radius.

More detail:
We accomplished several research tasks to improve N-sensor performance including demonstration in several field trials and the creation of an integrated data workflow. This enhanced the data and its use for temporal N measurements. To highlight, the SARIC project developed prototype N sensors and data transmission technology to cloud, streaming live field data continuously. All these tasks were accomplished within stipulated timeline as mentioned in the project proposal with the final validation trial completed in 2021. Our key objective was to develop a N selective membrane for based on double matrix polymeric membrane (DMPM) matrix and membrane assembly for ISE (N-Sensor) to improve the durability and accuracy in soils. To our knowledge, this is the first prototype sensor device deployed to sense soil N during the growing season in real-time. The proof of concept in-situ integrated N-sensor system enabled studies on N dynamics under fertilizer N inputs and accumulation of inorganic N in the soil profile to understand the N behaviour in soil-crop systems.
We conducted field trials with this novel N-sensor technology in 2018, 2019 and 2021 to study the problems associated with the environmental monitoring whilst tracking in-situ N using conventional means. Environmental variables i.e., soil temperature and moisture are a major challenge for N-sensors in real-time NO3- monitoring that can lead to problems in data extrapolation if not accounted for. To minimize this, data compensations for environmental variables were applied to accommodate N-sensors signal readings to measure the actual soil N content. Finally, N-sensors read-outputs were validated by integrating it to standard laboratory-based soil analysis, weather station data, environmental sensors (soil / temperature sensors), and crop canopy sensors for data accuracy.
Synchronizing N-sensors network data analysis with below soil and above ground measurements in real-time, holds a great advantage over traditional lab methods for decision making and fertilizer recommendations, which is the key driving force for development of sensing devices for precision agriculture. The 2-year experiment with N-sensor network systems showed how N supply from organic N mineralization decreased over time and how fertilizer applications changed in response to this.
Overall, our prototype can detect and report N levels in soil in real time and send data wirelessly to a remote device. We also showed how we analyze these signals and run analytics for data conversion to provide real-time soil N status to end users, usually farmers and agronomists. With the current investigation, looking at N-sensor data trends and soil N analysis, it was effective in minimizing over-fertilization, and maintaining good crop yields compared to the traditional and high N application rates. Our analytical approach creates a further opportunity to explore real-time N sensing during growing seasons focusing our research on precision agriculture.
Thus, the proof-of-concept for monitoring soil N with online N-sensor is of great importance to capture the real-time N fluctuations that is relevant to the field of soil hydrology
Exploitation Route We have developed a practical and analytical approach to support precision agriculture in the UK.

The work is currently being commercially exploited by Tony Miller at the John Innes Centre.

The sensors have also been used by several other research groups in the UK and overseas.
Sectors Agriculture

Food and Drink

Environment

 
Description • We have developed a simple, low-cost, field embeddable, a new type of sensors fitted with NO3- ion-selective double matrix polymeric membrane (DMPM) assembly to the conventional liquid filled electrode (N-sensor). N-sensor DMPM was designed and developed for real-time soil NO3- measurement continuously. • Validation studies are key to assess the functionalities of N-sensors in response to crop N uptake dynamics, lining up with time scale of N-fertilization, assimilation, and transformation in agriculture soil. We have developed models for N-sensors to compensate the environmental variable which is crucial for developing field-based N-sensors. The incoming signals were converted using data compensations for a final read-outputs indicating the actual nitrate levels in real-time. • Developed custom designed state-of- the- art Internet of Things (IoT) LoRaWAN loggers to support wireless data cloud transmission for real-time data readings from prototype soil N-sensors. • Prototype loggers were developed. LoRaWAN can collect the field data measurements and transmits to the cloud that can cover the sensors deployed within 10 km radius. We accomplished several research tasks to improve N-sensor performance including demonstration in several field trials and the creation of an integrated data workflow. This enhanced the data and its use for temporal N measurements. To highlight, the SARIC project developed prototype N sensors and data transmission technology to cloud, streaming live field data continuously. All these tasks were accomplished within stipulated timeline as mentioned in the project proposal with the final validation trial completed in 2021. Our key objective was to develop a N selective membrane for based on double matrix polymeric membrane (DMPM) matrix and membrane assembly for ISE (N-Sensor) to improve the durability and accuracy in soils. To our knowledge, this is the first prototype sensor device deployed to sense soil N during the growing season in real-time. The proof of concept in-situ integrated N-sensor system enabled studies on N dynamics under fertilizer N inputs and accumulation of inorganic N in the soil profile to understand the N behaviour in soil-crop systems. We conducted field trials with this novel N-sensor technology in 2018, 2019 and 2021 to study the problems associated with the environmental monitoring whilst tracking in-situ N using conventional means. Environmental variables i.e., soil temperature and moisture are a major challenge for N-sensors in real-time NO3- monitoring that can lead to problems in data extrapolation if not accounted for. To minimize this, data compensations for environmental variables were applied to accommodate N-sensors signal readings to measure the actual soil N content. Finally, N-sensors read-outputs were validated by integrating it to standard laboratory-based soil analysis, weather station data, environmental sensors (soil / temperature sensors), and crop canopy sensors for data accuracy. Synchronizing N-sensors network data analysis with below soil and above ground measurements in real-time, holds a great advantage over traditional lab methods for decision making and fertilizer recommendations, which is the key driving force for development of sensing devices for precision agriculture. The 2-year experiment with N-sensor network systems showed how N supply from organic N mineralization decreased over time and how fertilizer applications changed in response to this. Overall, our prototype can detect and report N levels in soil in real time and send data wirelessly to a remote device. We also showed how we analyze these signals and run analytics for data conversion to provide real-time soil N status to end users, usually farmers and agronomists. With the current investigation, looking at N-sensor data trends and soil N analysis, it was effective in minimizing over-fertilization, and maintaining good crop yields compared to the traditional and high N application rates. Our analytical approach creates a further opportunity to explore real-time N sensing during growing seasons focusing our research on precision agriculture. Thus, the proof-of-concept for monitoring soil N with online N-sensor is of great importance to capture the real-time N fluctuations that is relevant to the field of soil hydrology
First Year Of Impact 2019
Sector Agriculture, Food and Drink,Electronics
 
Description SARIC
Amount £283,012 (GBP)
Funding ID NE/R017425/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 09/2018 
End 09/2020
 
Title Soil nitrate sensors 
Description Development of improved soil sensor technology for the in situ evaluation of nitrate concentrations in soil. 
Type Of Material Technology assay or reagent 
Year Produced 2018 
Provided To Others? Yes  
Impact greater reliability in measurements. 
 
Description Collaboration with Yara 
Organisation Yara (UK) Ltd
Country United Kingdom 
Sector Private 
PI Contribution Supply of N sensors.
Collaborator Contribution Within this project, Yara are committed to hosting and collaborating in the nitrate sensor field trials which will be undertaken within our nitrogen response field trial network. In addition, we also agree to publicise the project as part of our on-going engagement activities at both in-house events (e.g. at our 5 annual N-Sensor training days which host 30-50 people each) and at external events (e.g. CropTec, Cereals 2017 and LAMMA).
Impact On-going activities
Start Year 2017
 
Description Geospatial monitoring 
Organisation Veris Technologies, Inc.
Country United States 
Sector Private 
PI Contribution Transfer of knowledge on sensors
Collaborator Contribution Transfer of knowledge on soil sensor deployment. Access to datasets
Impact On-going
Start Year 2018
 
Description Industry workshop on sensors 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Presentation in Warwick to agricultural industry.
Year(s) Of Engagement Activity 2017
 
Description Joint sensor workshop with Brazilian researchers 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact sensor building workshop for technology transfer to Brazil
Year(s) Of Engagement Activity 2018
 
Description Open Farm Sunday 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Open Farm Sunday. We had a big demonstration of the N sensor field trials and soil security
Year(s) Of Engagement Activity 2018
 
Description Radio interview 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Radio interview on soils on Radio Wales
Year(s) Of Engagement Activity 2020
 
Description Royal Welsh Show keynote made by PI 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Talk on the future of grasslands and new technologies.
Year(s) Of Engagement Activity 2018
 
Description SARIC annual meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Presentation to industry at the annual SARIC conference
Year(s) Of Engagement Activity 2017
 
Description Talk at the the Microbiology Seminar Series 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact Talk at the the Microbiology Seminar Series on Soil Sensor Technology
Year(s) Of Engagement Activity 2018
 
Description Talk to the Environment Centre Wales 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Professional Practitioners
Results and Impact Talk to the Environment Centre Wales on soil sensors
Year(s) Of Engagement Activity 2018
 
Description conference talk 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact Conference talk at the International Fertiliser Conference in Cambridge
Year(s) Of Engagement Activity 2019
 
Description meeting with fertiliser industry 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact meeting to discuss fertiliser use efficiency and the use of sensors.
Year(s) Of Engagement Activity 2019
 
Description talks with industry 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact We have held talks with many industries involved in soil testing.
Year(s) Of Engagement Activity 2019,2020
 
Description working with industry 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact knowldege transfer
Year(s) Of Engagement Activity 2020
 
Description workshops with welsh government on sensor technologies 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Industry/Business
Results and Impact small projects emerged
Year(s) Of Engagement Activity 2022