Back in the Nineteenth Century, John Bennet Lawes, a Victorian entrepreneur founded a research station at Rothamsted Manor.  It was to investigate the impact of organic and inorganic fertilisers on crop yield.  Lawes had a factory making some of the first artificial fertilisers.  The manor was to become the Rothamsted Experimental Station, now known as Rothamsted Research.  It has two of the longest running experiments - the Broad balk experiment and the Park Grass experiment - started in 1856. The Park Grass area was started by Lawes and Gilbert.  Its original purpose was to investigate ways of improving the yield of hay through the use of inorganic fertilisers or organic manures. Different strips of land received varying amounts of fertiliser to none.  It soon became clear that the different treatments had a dramatic effect on the species composition of what had been a uniform sward.  There are 35-45 plant species on the unfertilised plots but only 2 or 3 species on some of the fertilised plots. Fertilisers create conditions that allow fast growing grasses to dominate the vegetation.  More recently the plots have received attention (by Dr Balfour et al, Sussex University) for the number of pollinators that they support.  It was found that High levels of common fertilisers on grassland halves the pollinator numbers. Increasing the amount / availability of NPK (nitrogen phosphorus and potassium) on grassland reduces flower numbers five fold. Bee number were most affected.  There were 9 times more bees in untreated plants compared to plots with the most fertiliser input.   The number of bees, hoverflies, butterflies, wasps and flies on each experiment strip was counted. Whilst all pollinator types were present on untreated plots or with low fertiliser levels, only flies and beetles were present on high fertiliser plots. Interestingly, plots with lime added which changed the soil pH had more pollinators (50%) and flower species than those not treated with lime. as fertiliser use increases so there is a decrease in pollinator numbers.   Though these observations are for a specific area of managed grassland, they can be considered in a broader context.  Many grasslands and meadows, which offered homes to pollinators, have been lost in recent times,.  Over a similar period of time, farmlands across the country have extended (eg. hedgerow removal, ploughing meadows) and have been making significant use of fertiliser to improve crop yield, but the wider effects of these changes on insect populations and biodiversity in general has not received enough attention. The ‘excessive’ use of fertilisers can lead to soil eutrophication, air pollution, freshwater eutrophication and a loss of biodiversity.  It can favour botanical thugs )like nettles and invasive species.  We do know that there have been dramatic falls in insect numbers in recent years in what has been termed the ‘insect armageddon or the ‘insect apocalypse’.  Whilst there are many factors at play affecting insect numbers (such as the intensive use of pesticides), the maintenance or the reintroduction of natural areas [with low nutrient soil and native wild flowers] within farmland would at least offer sanctuary to many insects / pollinators that are vital for our crops.  Any reduction in the use of fertilisers would help reduce the CO2 emissions resulting from the Haber–Bosch process, used to produce ammonia and ammonium nitrate. Interesting fact : the institute employed Ronald Fisher in the 1920s to analyse data collected from many experiments.  His work and that of other statisticians means that many consider Rothamsted the birthplace of modern statistical theory (e.g. analysis of variance) and practice.