The reason for this, scientists from Lancaster University
have reasoned, is due to nitrogen. Although nitrogen is needed for plant growth it can also pose a risk as a significant pollutant. Most of the nitrogen causing pollution is from people, in the form of fertilizers, storm water runoff and sewage.
Nitrogen becomes a pollutant
if it leaches into rivers and contaminates the water supply. Nitrogen that leaches from the soil with drainage water forms a threat for water quality and high levels in drinking water can threaten human health. Too much nitrogen pollutes rivers and estuaries (bays) by causing too much algae to grow. These algae block out sunlight that sea grasses need. When these algae die and decay it takes oxygen from the water, causing fish to suffocate and to die.
According to the research brief
, the research was based on an analysis of twenty-two fields in the Yorkshire Dales, in England. The research was led by Franciska de Vries. For their study the researchers took a total of 162 intact columns of soil as part of a large scale field-observation and glasshouse experiment over several months. The research showed that hay meadows lose five times less nitrogen from the soil and therefore contribute a lower level of pollutants.
The findings have been published
in the journal PLOS ONE under the title "Extensive management promotes plant and microbial nitrogen retention in temperate grassland".