Pollution as a source of plant nutrients

Air pollution is a pressing concern in today’s world, and its effects extend beyond the environment and human health. On farmland air pollution is actually a significant contributor to the total nutrient load delivered to crops throughout the year. In this blog post, we will explore how nitrogen, sulphur, and other pollutants from the air affect plant nutrition, highlight plant species that can utilise certain pollutants, and discuss the role of atmospheric pollution in nutrient availability.

The introduction of nitrogen and sulphur compounds through aerial pollution has become a significant factor influencing plant nutrition. It is estimated that 25kg per hectare of nitrogen is added to European soils annually through this pollution source, affecting the nutrient balance significantly. Similarly, sulphur dioxide contributes to sulphate precipitation in rain, further impacting plant nutrition. Farmers in urbanised areas should consider these additional nitrogen and sulphur inputs when planning fertilisation strategies to ensure optimal nutrient availability for their crops.

Sulphur

Sulphur compounds present in air pollution can have detrimental effects on fungal populations both on plants and in the soil. Recent studies have shown that certain fungal species, including beneficial mycorrhizae and disease-causing pathogens, are susceptible to the toxic effects of sulphur. As farmers, it is important to be mindful of these impacts when managing fungal populations and implementing disease control measures.

Plants that CAN access nitrogen from the air

Interestingly, some plant species possess the ability to extract nitrogen directly from the air, specifically in the form of nitrogen oxide gases (NO and NO2). While extensive research is needed to identify species with this capability, a few examples have been studied thus far. The Japanese Kobushi magnolia (Magnolia kobus) and manna gum (Eucalyptus viminalis) have demonstrated the ability to obtain more than 10% of their nitrogen intake from nitrogen oxides. This knowledge opens up possibilities for farmers, especially those residing in urban areas with high nitrogen oxide pollution, to consider planting species that can utilise these pollutants.

Note: this form of nitrogen is different to elemental nitrogen (N₂), which no plant can directly access and use as a plant nutrient (only via the action of beneficial microbes in the soil).

Dust as a fertiliser

In infertile ecosystems, such as arid regions, dust has become the primary source of essential nutrients like magnesium, phosphorus, potassium, and calcium. These nutrients originate from various sources, including synthetic fertilisers from other farms, emissions from factories and vehicles, as well as dust from deserts and unpaved roads. Consequently, a significant portion of nutrients in these ecosystems comes from air pollution rather than natural weathering processes.

The role of carbon dioxide

Rising carbon dioxide (CO₂) levels due to industrial activities have also influenced plant nutrition. Elevated CO₂ stimulates plants to produce more exudates from their roots, which aid in capturing soil-bound nutrients. This increase in exudates leads to chelation and acidification of the soil, as well as enhanced microbial activity. Consequently, plants should theoretically have improved access to nutrients, thanks to the effects of atmospheric pollution.

Micronutrients from pesticides

Farmers frequently employ fungicides which contain zinc, copper, and sulphur. Regular application of these fungicides, particularly on fruit crops, can supply sufficient levels of these nutrients, preventing deficiencies. However, it is essential to strike a balance to avoid excessive accumulation and potential negative effects on plants and the environment.

We therefore suggest that farmers, especially those near urban areas, should understand the intricate relationship between air pollution and plant nutrition. The influx of nitrogen, sulphur, and other pollutants from the air significantly affects nutrient availability and influences fungal populations. Furthermore, knowledge about plant species capable of utilizing certain pollutants offers exciting opportunities for designing resilient gardens in urban environments. By staying informed and adapting farming practices accordingly, farmers can navigate the challenges posed by atmospheric pollution and ensure the optimal nutrition of their crops.

If your soil is deficient in sulphur, consider using our soluble sulphur fertiliser.