Soils and climate change – changing rainfall

Hi there, I’m Kirsty Ross from Lancaster Environment Centre. I’m a PhD student, and a technician here. So the project that I’m working on is looking at how nutrients might change with climate change in the UK. So the project’s called NutCat 2050, and that stands for Estimating Nutrients in Changing Climates, and we work with the Met Office and many other universities to have a look at this problem. So we use the UKCP09 climate change predictions for the UK. And that basically says that we’re going to see hotter, drier summers and warmer, wetter winters. So we want to know what that means for phosphorus especially. So we add phosphorus to agriculture environment via slurry or just fertiliser application.

And in the case of fertiliser, only about 20% sometimes is taken up by plants, and the rest of it stays in the soil. So when it rains, we get overland flow and subsurface flow. And in this, we can have particles that have phosphorous attached to them, and we have phosphorus in solution, and this causes eutrophication. So this produces a lot of algal biomass, because they’re getting so many nutrients in the water. And this then depletes our water quality as it costs more to treat it, as when we abstract it, we want clean water for drinking and other uses. So what we have here is called the transfer continuum. We have source, which might be slurry.

Then we have mobilisation, which might be rain impact, and then transfer, which might be overland flow and delivery into the watercourse. And we want to see on this project what part of those continuums might change with climate change. So we’re working with three National Demonstration Test Catchments, the Eden, which is in Cumbria in the Northwest of England, the Wensum, which is in the Southeast of England, and the Avon, which is in the Southwest of England. So I’ve got three different soils I’ve brought from the field into the lab, and we’re drying them for different lengths of time.

So this is going to see whether those really hot summers and these really wet winters, what affect are they going to have on the soil and that phosphorus transfer from soil to water? So in the next film, you’re going to see me and in lab and all the different types of soil, and you’re also going to see we’re going to put lots of water on it and then measure the amount of phosphorous that comes out the end, and that’s called leachate, and that’s what we’re going to measure. So here I am in the lab, and I’ve got my different soils, which have been dried for different lengths of time. And I know the water content of all of these.

And then I’m going to put them in these little funnels. Then I’m going to re-wet them with 50 ml of water over two hours, and then collect the leachate in these little tubes and analyse the leachate for different fractions of phosphorus. So I just put these filter papers over the top of the soil to make sure that it’s nice and evenly re-wetted.

So here I am with 5 ml of water, and I’m going to apply 5 ml equally over the two hours to re-wet them.

So here I’m preparing the leachate into a micro plate. I have filtered and unfiltered samples, half are digested in an acid in order that I can analyse for the different forms of phosphorus I’m interested in. I then apply a reagent and wait for the colour to develop. In this method, it would turn blue. Basically, the more blue it is, the more phosphorus. I then simply put the plate in the plate reader, which gives me the individual absorbances of the samples. I can then use this to calculate the concentration of phosphorus in the leachate. Simple.

So my lab and field work is going to be used to help improve nutrient models, and these nurtrient models use climate change and land use change information to try and predict what our environment might look like into the 2050s. And this information can be used for policy makers and stakeholders.