8 November 2016

The race to create super crops: what solutions to increase the efficiency  of use by plants of soil nutrients?

Nitrogen (N) is a major element in plant composition and a key factor of plant growth. Although nitrogen is a widely available element in our environment (the molecule N2 composes 80% of our air), it cannot be assimilated directly in its molecular form by most plants, particularly cereals. Legumes, however, because of their symbiotic association with a bacteria, Rhizobium, have that capacity.

Historically and especially since World War II, priority has been given world-wide to providing nitrogen to plants in a form that can be assimilated by them, through the application of different types of chemical fertilisers. According to FAO, the world has been using 109 million tons of nitrogen nutrients in 2014, 22% more than in 2004. Other important sources of nitrogen nutrients are animal manure, crop residues and crop associations (with legume plants or legume trees as for exemple in West Africa through the association of millet with niebe beans and/or acacia albida trees).

There are several problems with chemical nitrogen fertiliser.

First, only a fraction of the nutrients provided are actually absorbed and used by plants. It is estimated that only 30 to 50% of the fertiliser spread on crops is actually being used by plants, the rest being washed away to contaminate ground water, rivers, lakes and the sea, with dramatic consequences on health, eutrophisation of water bodies, growth of algae, etc…

Second, nitrogen fertiliser has a high energy content as the chemical reaction required to transform N2 into chemical forms that can be assimilated by plants (the Haber reaction) requires a large amount of energy. Some estimates place at 1% the share of global energy consumption that goes into the manufacturing of nitrogen fertiliser.

Third, the price of nitrogen fertiliser has increased tremendously of recent. For example, in the US, the farm price of a popular fertiliser like ammonium nitrate has more than doubled between 2003 and 2013 (from $243 to $544 per ton). Similar changes have been observed for other nitrogen fertilisers in the US (USDA/ERS), in the UK (AHDB) and in France (INRA).

In reaction to these issues, the fertiliser industry, which has an annual turnover of well above $150 billion, and its association (IFA, based in Paris) have, as early as at the time of the 2007/08 crisis, emphasised in their messages the need to use fertilisers in a more efficient way, through better targeted application (e.g. precision agriculture, slow or controlled-release fertiliser, etc.), which allows reduced application rates and costs.

In parallel to this evolution, the seed industry has been searching for more efficient use of fertilisers by crops. Some media have named this drive as the “race to create super crops” (Nature).

One thrust of research has been, at cellular level, to identify possible limiting physiological factors to the metabolization of nitrogen and overcome them by creating of “GMO super crops”. This is the approach adopted by companies like Arcadia Biosciences, and recently FuturaGrene who are working on the creation of nitrogen-efficient poplar trees for agrofuel production who should require up to 50% less nitrogen than existing varieties. Prototypes of enhanced corn, wheat, barley, soybeans, rice, cotton, alfalfa, canola and of some trees have also been created and licensed, but for the time being no nitrogen use efficient (NUE) crops have yet been commercialised by Arcadia’s partners like seed majors Monsanto and DuPont, the reasons being stability of the varieties created, strong variability of performance in different ecological conditions and the complexity of plant metabolism which is not just the result of activities of a gene or of set of genes. But scientists say, it is expected that such improved varieties will soon be on the market.

Another thrust has been to seek ways of improving the efficiency of the interface between plants and the soil by boosting biological activity around roots. At hungerexplained.org, we have already reported the efforts made by Adaptive Symbiotic Technologies and Indigo Agriculture to create or enhance symbiotic relations between plants and microorganisms including for raising the nutrient absorption capacity of plants [read here].

For leguminous crops, who are able to fix nitrogen through the Rizhobium bacteria, as already mentioned earlier, the limiting factor is phosphorus. In this case, research has been focusing on the search for existing good performer varieties on the basis of the size of their root system which is the interface between plant and soil. There, for example, researchers have been able to find bean varieties with a large root system that could achieve as much as three times the yield of other bean varieties. This effort, based on conventional breeding, seems to give better results than genetic engineering that leads to the production of GMOs. Similar research with cereals (maize in particular, but also paddy by IRRI) have also shown that varieties with larger root systems perform better.

Our reaction, at hungerexplained.org, to these developments is that we are convinced that reducing the consumption of chemical fertilizer, particularly of nitrogen fertiliser, is a must because of the negative effects it has on our environment, the climate and health. This should be done while respecting two vital principles:

1. •the solutions proposed should be built on processes that exist naturally and not be artificially produced
   

2. •the solutions proposed should be accessible by all producers, particularly poor producers.
   

Failing to respect these two fundamental principles would bring the risk of creating unexpected negative impacts that could have major implications and of excluding from advances made, those who need them most, i.e. the poor and undernourished farmers.

————————————-

To know more:

1. -Gilbert, N., The race to create super-crops, Nature, 2016
   

2. -Vezina, K., Nitrogen-efficient crops: The holy grail of agricultural biotech? Genetic Literacy Project (Science, not ideology), 2013
   

3. -International Service for the Acquisition of Agri-biotech Applications, Nitrogen Use Efficient Biotech Crops, ISAAA Website
   

4. -Arcadia Bioscience, Nitrogen Use Efficiency, Website
   

Earlier articles on hungerexplained.org related to the topic:

1. -To produce more: build an alliance with nature rather than combat it, 2016
   

2. -Food, Environment and Health, 2014

Last update:    November 2016

For your comments and reactions: hungerexpl@gmail.com