Reduction in Air Pollution and the Use of Polysulphate

The importance of sulphur to healthy plant growth is well recognised. Without S, a constituent of all protein and thus an essential nutrient for all plants and animals, growth and productivity are seriously stunted. Historically, crops in industrialised parts of the world would rely on the sulpur-containing pollutants in the atmosphere for the S they need; pollutants including sulpur dioxide produced by industry, particularly the burning of fossil fuels.

Costs to Health Outweigh the Benefits to Soils

The indirect benefit from air pollution of good soil S levels is far outweighed by the cost of air pollution to human health and the wider environment. Initiatives to use cleaner energy and less polluting manufacturing processes to reduce emissions of pollutants mean that S emissions in several parts of the world have already fallen. As a result, less S is falling to earth and into soils.

Falling Levels of Sulphur from Air Pollution

Air pollution levels are changing in different parts of the world. Across Europe, reveals the European Environment Agency, emissions of sulphur dioxide decreased by 76% between 1990 and 2009.

Past emission trends of sulphur oxides. National emissions reported to the Convention on Long-range Transboundary Air Pollution (LRTAP Convention) provided by European Environment Agency (EEA)

According to the Earth Observatory – which shares discoveries about the environment, earth systems, and climate that emerge from NASA research – the images showing trends of sulphur emission in Asia, the region that now emits the most sulphur dioxide in the world, are interesting. While India saw levels of the gas double between 2005 and 2014, the air over eastern China saw sulphur dioxide decline starting in 2007.

Maps from the NASA Earth Observatory comparing emissions of sulphur dioxide in China during two periods in the first two decades of this century show a steady decline in air pollution which will have resulted in less sulphur reaching the soil.

Multi-year averages of sulphur dioxide concentrations as measured by OMI for 2005-2007. (Source: NASA Earth Observatory).

Multi-year averages of sulphur dioxide concentrations as measured by OMI for 2011-2014. (Source: NASA Earth Observatory)

Meanwhile in India a 60% increase in sulphur dioxide emissions between 2005 and 2012 is evident in the Earth Observatory maps.

However Indian air pollution, such as the harmful smogs in Delhi, is not likely to be tolerated long-term. As in other parts of the world, anti-pollution policies will be brought in to reduce the emissions and India’s farmers will no longer get their sulphur for free.

Soil Testing Essential for Precision Fertiliser Use

Farmers worldwide need to know their crops’ nutritional needs. Measurement of available sulphur in the soil is essential. A simple calculation is then required to calculate the crop’s need for S and other nutrients. Polysulphate is a uniquely balanced fertiliser that is high in sulphate which is internationally admired and relied on to provide what crops need.

The worldwide trend of the reduction in production of sulphur dioxide and pollution of the atmosphere means that S, so important for plant growth, is (happily) no longer falling free from the sky. It is also good news that, in Polysulphate fertiliser, farmers have an effective replacement at the ready.