First of all I am so sorry there has been a gap on posting blogs over the past few months!

I am developing a new TalkingGrass blog with an online shop called Grassy and Green and was hoping to launch this spring. Unfortunately it is taking a bit longer than anticipated – so I will be blogging here for now!

160 years of the Park Grass Hay Experiment
I was astounded to learn that the longest running grassland experiment has been running not far from me, at Rothamsted Research at Harpenden in Hertfordshire. I was excited to be invited to see it for myself, at an event to celebrate 160 years since its formation.

The experimental grass plots were set down in a hay meadow near the front of the house where Victorian scientists Sir John Bennet Lawes and Sir Joseph Gilbert lived and worked.

Lawes had a patent on a superphosphate fertiliser, so felt he needed to know what effect fertilising grassland would have. Plots were drawn out and have remained the same shape – although sub-divided to allow for lime applications, since the start.

They are cut for hay in June – allowing some self-seeding, and again in October. Even now, the plot boundaries remain amazingly sharp and changes in soil properties and species occur over only 30cm between them.

Biodiverse plotsBotanical diversity
The botanical composition across the site was the same in the beginning, but now is markedly different, depending on the nutritional supplements applied.

Essentially, the plots that were fed with nitrogen or phosphorous or farmyard manure increased their yield of hay to 6-9t dry matter (DM). But their botanic diversity declined, featuring mainly grasses like cocksfoot and meadow foxtail.

The control plots have the most species, including bugle, bird’s foot trefoil and pignut, but only yield 3t DM/ha.

Some plots have become very acid, due to the application of ammonium sulphate – down to pH 3.5. Here only two grasses survive and thrive – sweet vernal grass and Yorkshire fog.

Relevance today
While running for 160 years is to be applauded in itself, do these plots still serve a purpose? Well yes in several ways – including the observation of environmental and climate change in our ecosystems.

Some plots have become very acid due to the application of ammonium sulphate – down to pH 3.5.A paper published just last December in Nature, highlighted how pollution from atmospheric nitrogen deposition had led to species decline at Park Grass, but also that cleaner air is now leading to biodiversity recovery.

Perhaps more exciting is the fact that PhD students are starting to investigate the differences below ground, focusing on the bacteria and fungi living in the soil.

Park Grass is the main monitoring site at Rothamsted for the Environmental Change Network (ECN), where weather, flora and fauna, and water and soil conditions are monitored to detect any changes.

Data, including yields and botanical composition, are also stored in the Electronic Rothamsted Archive (e-RA). They are available, with thousands of archived samples, to researchers in the UK and abroad for future studies.

Happy 160th Birthday to the Park Grass Hay Experiment. Here’s to the next 160!

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