No fertiliser? No problem

It’s common knowledge that not all governments are in a position to provide subsidies for their farmers to purchase fertilizers. Yet they need not be too concerned, as according to scientists, the current levels of nitrogen fixation (combining unreactive atmospheric nitrogen with hydrogen to produce ammonia) globally may soon see heavy restrictions placed on fertiliser use, and famers across the world may soon be encouraged to revert back to traditional and sustainable methods of fertilizing their crops such as planting legumes and animal manure.

Apparently, human intervention in the nitrogen cycle results in 190 teragrams of reactive nitrogen produced every year, with one teragram being equivalent to one million tonnes. This is spelling disaster for both humans and the environment, as reactive nitrogen contributes to respiratory diseases, acidifying forests and grasslands, and eutrophication (oxygen depletion) of global water systems.

In Sub-Saharan Africa, fertiliser usage makes up only 13kg per hectare, compared with 73kg in the Middle East and North Africa, and 190kg in East Asia and the Pacific. So whilst these figures may be undesirable for Africa in terms of increasing food production, the silver lining may well be that as the contribution to reactive nitrogen in the environment is considerably lower than other regions, Sub-Saharan Africa and other poor regions will have less adjusting to do once global restrictions are put in place – and they are coming.

According to James Galloway, professor of environmental sciences at the University of Virginia in the US, the first target should be fossil fuels, at nitrous oxide is up to 300 times a more dangerous greenhouse gas than carbon dioxide. If successful, this intervention should reduce the amount of reactive nitrogen by about 18 teragrams per year. The next step would inevitably be to optimise the way reactive nitrogen is produced and utilised in food production, as producing ammonia for fertiliser use via the Haber process is incredibly inefficient.

Natural ammonia production occurs via the nitrogen-fixing bacteria Rhizobium, which is predominantly located in the root nodules of leguminous plants. These bacteria provides plants with ammonia in exchange for the nutrients it needs to survive. Farmers have long known the link between planting legumes and improving soil fertility, as legumes are perfectly capable of growing in poor soil that cannot normally accommodate other crop types. After harvesting, the decayed roots that remain in the soil release organic nitrogen compounds that are available for the next generation of crops, so farmers can harness the potential of this natural fertiliser by rotating between their leguminous and non-leguminous crops.

Thus, farmers in resource-limited settings who may not have the resources to invest in fertilisers can rest assured that in addition to the manure from their livestock, the utilisation of the microbes that live in the roots of their broad beans, garden peas and peanut crops, may soon be universally adopted by farmers everywhere, in the global attempt to save the world from itself.