Main Objectives
Alongside the lower emission AN there are a range of fertilisers based on organic materials. These offer a lower carbon alternative as they are manufactured using recycled materials or sourced from materials that do not require energy intensive processing to be useable as fertiliser. These products raise more questions than the AN alternatives as they release N slowly. With sugar beet requiring all of its N early to support rapid canopy growth to maximise yield as well as resistance to pests and diseases there could be challenges in late season N uptake. This can lead to oversized canopies at the expense of root growth as well as supressing sugars through increased impurities and ultimately reducing yield.
In addition to this there are bacteria and photocatalysts that can be foliar and/or soil applied to fix atmospheric N2 and reduced crop N demand which can further reduce artificial N inputs. There is a clear need to test some of these products to identify those which provide the N requirements that are compatible with the demands of the sugar beet crop. This is an issue that affects all sugar beet growers, and therefore has relevance to the whole beet growing area.
Ammonium nitrate fertiliser emissions account for 10.6% of global emissions from agriculture with synthetic fertiliser production accounting for 38.8% and in field N2O emissions at 58.6% (Menegat et al., 2022). It is claimed alternative AN products made with renewable energy can significantly reduce the emissions from manufacturing can reduce emissions compared to traditional manufacture by up to 90% (Yara, 2024). This highlights that significant savings can be made through switching to AN fertiliser made with renewable energy. However, this does not necessarily address the issue of the N2O emissions. One approach to reduce N2O emissions is to place fertiliser to reduce the amount used as burying AN reduces the speed of volatilisation and gaseous emissions (Wu et al., 2021).
The next step to reducing emissions is to move away from AN. Organic matter-based products can help reduce N2O emissions through slower release of nutrients compared to AN. Much like inhibited urea (Cantrella et al., 2018) these products are more stable than AN reducing the amount of volatilisation. Some products such as CCm fertiliser (CCm Technologies, 2024) claim to reduce volatilisation and leaching by up to 80% compared to traditional AN. However, there is a concern over late N release as previously outlined.
Alongside the renewable AN and slower release fertiliser there are also products based on nitrogen fixing bacteria and photocatalysts. These products claim to enable N from the air to be fixed and available for uptake to the plant. Depending on the product they can be applied to the soil or the plant itself. There is little data on how these products work in sugar beet and this means there is an opportunity to explore this. Much like the slow-release N products although they are expensive now and not standard practice they may be a useful tool in the future and therefore evaluating them now will generate useful information for sugar beet growers.
This is an important opportunity to start research that will help inform and support growers on adopting different fertiliser products, which is the likely direction of travel if pressure from legislation and customer demands continue. Through undertaking this work in house BBRO will have ownership of the data which can be shared with growers in an honest and transparent way. If this work was undertaken commercially BBRO would not have ownership of the data and the fertiliser companies would be free to use the data as they want, likely only presenting results that support their commercial objectives.
Menegat, S., Ledo, A. and Tirado, R., 2022. Greenhouse gas emissions from global production and use of nitrogen synthetic fertilisers in agriculture. Scientific Reports, 12(1), p.14490.
Cantarella, H., Otto, R., Soares, J.R. and de Brito Silva, A.G., 2018. Agronomic efficiency of NBPT as a urease inhibitor: A review. Journal of advanced research, 13, pp.19-27.
Wu, P., Chen, G., Liu, F., Cai, T., Zhang, P. and Jia, Z., 2021. How does deep-band fertilizer placement reduce N2O emissions and increase maize yields?. Agriculture, Ecosystems & Environment, 322, p.107672.
As the industry aims to reduce nitrogen rates and without wanting to end up with a large treatment list the fertilisers will be tested at a reduced rate of 100kg/N/Ha total rather than the traditional 120kg/N/Ha. One AN treatment will be at this 100kg/N/Ha rate as a control but there will also be a 120kg/N/Ha and 60kg/N/Ha rates. This then means the trial also functions as a look at sugar beet crop performance at lower N rates and the results from these AN treatments can be used to construct a rough fertiliser response curve and check the SNS is as predicted.
Alongside the field trial there will be controlled environment work to assess the physiological effects of the plant applied nitrogen fixing products. These products are likely to be heavily affected by the weather conditions in the field with bacteria performing better at warmer temperatures and in unstressed plants. Before evaluating these products in the field there will be controlled environment studies to show if the products have an effect on the sugar beet. There is then the potential to try them in the field in following years where biotic and abiotic factors may interact with the product performance. The products currently identified for this study are:
- Corteva Blue N - methylobacterium symbioticum
Vixeran - azotobacter salinestris - R-Leaf- photocatalysts
All contain N fixing bacteria or photocatalysts suitable for foliar application.
