By Jonathan Holland, Agri-Environment Branch, Agri-Food & Biosciences Institute
The Long-term Slurry (LTS) site is one of the longest-running grassland experiments in the UK and probably the oldest grassland experiment on slurry applications in the world. A special event was held on 16th September 2021 to celebrate and acknowledge >50 years of the Long-term Slurry Experiment.
The grassland experiment was established in 1970 at the Agri-Food Biosciences Institute (AFBI) research farm in Hillsborough, Co. Down.
The study has become more valuable over time as Pieter-Jan Schön, director of environment and marine sciences at AFBI, pointed out that “challenges such as carbon sequestration were not on the political agenda 50 years ago".
The experiment has provided key insights into how agricultural grasslands in NI may respond to long-term organic and inorganic nutrient applications.
Dr. John Gilliland, chair of the Northern Ireland, Sustainable Agriculture Land Management Expert Working Group, commented: “It was excellent to visit the long term slurry experiment at AFBI’s site in Hillsborough and to celebrate its 50 years of providing us in the industry really sound data of the long term consequences of how we manage our soils, swards and our slurries.
In the month running up to COP26, when the world will discuss our future direction to achieve carbon net-zero, having historic reputable data coming from the Long-term Slurry experiment is essential in highlighting what are the right directions for us as farmers to take.
"This experiment is a huge credit to AFBI and to DAERA for having the foresight, not only to set it up, but to continue with the funding of this vital research.”
Long-term Slurry Experiment
The Long-term Slurry Experiment is a three-cut silage system with zero-grazing and includes eight treatments: a control (which receives no nutrient applications), mineral fertilizer application and three different application rates (high, medium and low) of cow and pig slurry.
Research at this site has provided insights on yield response, forage quality and fertilization effects on soil properties such as the dynamics of key nutrients (nitrogen and phosphorus) and carbon storage.
For example, over the past 50 years, soil carbon stocks under cow slurry applications have increased at a rate between 400kg and 900kg of carbon per ha/year. Also, soils across all experimental treatments do not seem to have reached yet a carbon saturation level.
The outdoor event was organized at AFBI Hillsborough by invitation within Covid restrictions. Dr. Dario Fornara and Dr. Jonathan Holland from AFBI, who oversee the experiment, briefly spoke about the success of this experiment in terms of promoting scientific knowledge and impacts on science, policy and society.
For example, research methodology and findings from this experiment have allowed AFBI to contribute to guidelines published by the Food and Agriculture Organization of the United Nations (FAO) on how to measure and model changes in soil carbon stocks across livestock-based systems worldwide.
Rates of soil carbon accumulation measured within the experiment have been crucial to inform Farm Carbon Calculators in NI and estimate the soil carbon sequestration potential of agricultural grasslands to improve the Green House Gas (GHG) inventory associated with the Land Use and Land Use Change and Forestry (LULUCF) sector in NI.
Dr. Jonathan Storkey from Rothamsted Research, Harpenden, UK gave a keynote lecture on “The value of long-term grassland research to theory and practice: insights from the Park Grass Experiment”.
The Park Grass experiment was established in 1856 and is now the world’s longest-running grassland experiment. Dr. Storkey gave a fascinating insight into significant plant species composition changes over time. The lecture highlighted the improved understanding of agricultural grasslands to help deliver multiple ecosystem services and inform policies on green growth and biodiversity.
Prof. Nigel Scollan, director of the School of Biological Sciences, Queen’s University of Belfast, said: “The long-term slurry experiment has enabled Northern Ireland to build a research platform that is unique globally and vital to advancing knowledge to help support our farming systems.
These long term facilities also provide an excellent training resource for both undergraduate and postgraduate students. Under the AFBI-QUB Alliance, Queen’s is looking forward to undertaking further research with AFBI on sustainable land use”.
The event was financially supported by AFBI and the Ecological Continuity Trust (ECT). The ECT is a charity which works to secure, maintain and promote the UK’s long-term ecological field experiments.
Ben Sykes, executive director of the ECT, said: “The Hillsborough LTS experiment is right up there with the longest-running grassland experiments in the UK.
"In these times of environmental change, such experiments are more valuable than ever as bellwethers of what we can expect to happen to the ecosystem services grasslands provide in the future”.