Biostimulants and nitrogen management: an assessment of famer-led trials (Angus Smart Arable Farm 2021)

This project supported the Angus Smart Arable Farm Group. Specifically, it aimed to enable them to meet trial objectives and answer questions set by the group’s farmers. Activities within this project were designed to complement the farmer-led investigations to get the maximum benefit from the trials, data and analyses.

The winter wheat and spring barley trials were located at two farms in Angus, Scotland. In 2021, the trials aimed to evaluate ways to reduce nitrogen (N) fertiliser rate, while maintaining yields. The trials included Nurture N, which is marketed as a liquid fertiliser amendment.

Prior to the commencement of this project, the trials were established by the farmer group. This project commenced with a kick-off meeting, involving the researchers and participating farmers. At this meeting, the following was discussed: the farmers’ hypotheses and questions, the trials, the potential assessments, and the value added to the overall understanding. Because treatments had been applied before this project commenced, it was too late co-design the trial layouts. However, it provided an opportunity to discuss robust trial designs with the group. During the trials, researchers conducted several site visits and facilitated crop assessments. Grower participants were provided with data at update meetings.

The winter wheat trials identified significant yield reductions in response to reducing nitrogen rates (by 60kg N/ha and 40 kg N/ha) at the two participating farms. In the Strathmore trial, the application of Nurture N and additional nutrient and biostimulant products had no effect on yield in the reduced nitrogen situation. Physiologically, the reduced nitrogen rate resulted in a significantly lower number of ears/m² and grains/m² in both trials. Notably, at Strathmore, the reduction in nitrogen rate also resulted in a lower thousand grain weight (TGW), whereas there was no effect of the reduced nitrogen treatment at Grange of Conon.

In contrast to the winter wheat trials, there was minimal effect of the reduced nitrogen treatment with Nurture N applied to spring barley at Grange of Conon. The results indicated that the current farm standard application rate may be in excess, offering scope to reduce rates. In the Strathmore experiment, the results showed a large yield increase (more than 1 t/ha) in response to the Nurture + treatment (note: this did not include a reduction in nitrogen rate). Because there was no replication, this result should be treated with caution.

Any further trials to understand how to reduce nitrogen rates while maintaining yields should build on the lessons from these initial trials. Future trials should include a focus on robust trial designs (with replication), the optimum application timings, rates of products being tested, as well as complimentary measurements to help explain yield effects.