Sam Judd: Our nutrient world

In the second of a series of articles, Sam Judd - our Young New Zealander of the Year and co founder of Sustainable Coastlines - reflects on the challenges and opportunities that the United Nations Environment Program faces with regard to oceans.

Perhaps the biggest environmental problem we currently face is the contamination of our waterways by nutrients.

Ever since the Land and Water Forum released the fact that most of the point source pollution has been curbed by regulations, the main threat we have in New Zealand comes from diffuse sources that are mainly from agriculture.

When Fritz Haber and Carl Bosch designed a way to combine hydrogen and nitrogen (from thin air) and produce ammonia they were hailed as heroes and accordingly received Nobel Prizes for their work. The fertiliser they created caused a population boom, as we were suddenly able to artificially supplement plant growth and grow huge amounts of food.

What Haber and Bosch didn't know was that when nitrogen fertiliser is not managed well, it leaches into the waterways, damaging human health, causing toxic algal blooms, killing fish, threatening sensitive ecosystems and contributing to climate change.

The ethical debate is always difficult when it comes to food. Our blossoming population will continue to grow, we will have to find a way to feed everyone and fertiliser will be required to do this. While organic farming is better, the International Fertiliser Development Centre says that if the world's 1.5 billion hectares of farm land were farmed organically, there would only be enough food for 2.4 billion people, about one in three of those in the world today.

To support population growth since the 1960s, human use of synthetic nitrogen has increased nine-fold globally, while phosphorus use has tripled and a further increase will be required over the next forty years too.

One has to ask though - how much food to we really need?

The lead authors of the United Nations-backed Global Partnership on Nutrient Management say in their report Our Nutrient World that 80% of the harvested nitrogen in the world ends up feeding livestock rather than people and that Europeans eat 70% more protein than needed, while sub-Saharan African farmers are desperately low in nutrients and thus undernourished.

So the question becomes one of food luxury, rather than food security. The biggest impact that we as individuals can have is to eat less meat. This doesn't mean everyone has to be a vegetarian, it just means we need to reduce how much is consumed.

At an industry level, there are some major gains to be made by improving nutrient use efficiency, which makes immediate sense. On average over 80% of nitrogen and 25-75% of phosphorus consumed end up lost to the environment, wasting the energy used to prepare them (which collectively makes up 2% of global energy use) and causing pollution through emissions of the greenhouse gas nitrous oxide and ammonia to the atmosphere, while nitrate, phosphate and organic compounds are also lost into the water.

The United Nations has a goal of a 20% relative improvement in full-chain nutrient use efficiency by 2020 that would save about 20 million tonnes of nitrogen per year. It would also deliver an estimated improvement in human health, climate and biodiversity worth around $170 billion per year.

To do this farmers need to think about the four 'R's of efficient nutrient use, while basing their applications on real science (rather than from a soil consultant with a vested interest in selling fertiliser). These are using the right source, the right rate, at the right time in the right place.

When these factors come together, you get a farm that requires less work, less spending and produces a higher yield with lower impact on the environment.