Our recent听听has听explored how long-term changes in land use, agriculture, atmospheric pollution and human waste generation and management has changed the flows of nutrients through our waterways.
Centuries of nutrient change听
The past two centuries have seen huge changes in our landscapes and ways of life听that have听driven听big changes听in听the flows of macronutrients,听carbon nitrogen and phosphorus,听in our environment.听Agricultural expansion has changed plant cover, disrupting plant-soil nutrient cycles, and with the Green Revolution and the widespread adoption of inorganic fertilizer use came large additions of nitrogen and phosphorus听to the environment. Natural ecosystems too have been affected by large additions of nitrogen from atmospheric pollution, driven by rising fertilizer use and fossil fuel burning.听Rising听populations, the introduction of the toilet,听and the use of new products in the home such as detergents,听have听also听meant that听wastewater has changed the flow of nutrients around our environment.听听
A nutrient puzzle听
All this听simultaneous,听long-term,听widespread听change presents us with puzzle听鈥� how can we understand how these various drivers have contributed to nutrient听cycle听change听and听the consequences for terrestrial and aquatic ecosystems, and what can we learn that helps us manage nutrient flows and the negative knock-on effects in future? Computer modelling offers us a way to unpick this puzzle.听听
The Long-Term Large-Scale project, funded by the Natural Environment Research Council鈥檚 Macronutrient Research听Programme,听brought together听a diverse set of听researchers听to build an integrated model that interconnects听nutrient processes听from atmosphere to plants and soils to waterways.听John Quinton and Jess Davies were part of this modelling effort contributing key components in plant-soil biogeochemical and soil erosion modelling.听听
Modelling the past to understand the听future听
The听, published in Science of the Total Environment, communicates some of our findings from a freshwater perspective. Our modelling analysis indicates听that the rapid increase in the use of agricultural听fertilisers听after the second world war, and the rising human population, led to a rapid rise in听nitrogen听and phosphorus听fluxes to rivers, with nitrogen export to rivers quadrupling听and phosphorus increasing by a factor of 10听(see figure exert below).听During this period, the modelling shows that the dominant source of听nitrogen听to听rivers听switched听from听intense听grasslands听to arable, the dissolved N export to rivers quadrupled, and P from human waste听entering our waterways听increased by ~600%, despite听waste water听treatment.听听
This work highlights the extent to which we as humans have modified our nutrient world听in the past, but it can also help us make a better future. This research and the modelling tools produced听can听help听inform national nutrient budgets and targeting of water quality听measures, and听help us set realistic targets for nutrient export and water quality status.听
Exert from figure in Bell et al 2021: Export of carbon, nitrogen and phosphorus to UK waterways from soils 1800鈥�2010.
If you are interested in other findings form the Long-Term Large Scale Macronutrient Change project, more outputs from the project are listed below:听
- Measured estimates of semi-natural terrestrial NPP in Great Britain: comparison with modelled values, and dependence on atmospheric nitrogen deposition. Edward Tipping, Jessica A. C. Davies, Peter A. Henrys, Susan G. Jarvis, Edwin C. Rowe, Simon M. Smart, Michael G. Le Duc, Robert H. Marrs, Robin J.听Pakeman听(2019) Biogeochemistry 144, 215鈥�227.听听听
- Impact of two centuries of intensive agriculture on soil carbon, nitrogen and phosphorus cycling in the UK.听S.E.Muhammed, K. Coleman,听Lianhai听Wu, V.A. Bell, J.A.C. Davies, J.N. Quinton, E.J. Carnell, S.J. Tomlinson, A.J. Dore, U.听Dragosits, P.S. Naden, M.J.听Glendining, E. Tipping, A.P. Whitmore (2018). Science of the Total Environment 634, 1486鈥�1504.听听听
- Long-term increases in soil carbon due to ecosystem fertilization by atmospheric nitrogen deposition demonstrated by regional-scale modelling and observations.听 E. Tipping, J. A. C. Davies, P. A. Henrys, G. J. D. Kirk, A. Lilly, U.听Dragosits, E. J. Carnell, A. J. Dore, M. A. Sutton & S. J. Tomlinson.听 Scientific Reports 7, Article number: 1890 (2017)听听听
- 150 years of macronutrient change in unfertilized UK ecosystems: Observations vs simulations.听 JAC Davies, E Tipping, AP Whitmore.听 Science of the Total Environment (2016)听听听
- Long-term P weathering and recent N deposition control contemporary plant-soil C, N, and P. J.A.C. Davies,听E.Tipping, E.C. Rowe, J.F. Boyle,听E.Graf听Pannatier, V. Martinsen (2016) Global Biogeochemical Cycles 30, 231-249.听听听