Editorial

What is the most critical issue facing agricultural research?

If you were asked to name the most critical issue for agricultural research what would your reply be? Anyone who has seen recent headlines will know that the United Nations estimation of world population for 2050 is 9 billion. While the rate of global population growth is slowing, it appears the world will reach this target. Critical to this happening is an adequate food supply. The Food and Agriculture Organisation of the United Nations notes (FAO 2009) that “annual cereal production will need to rise to about 3 billion tonnes from 2.1 billion today and annual meat production will need to rise by over 200 million tonnes to reach 470 million tonnes” in order to feed an increasingly urban population. The FAO argues that this is possible, however, biofuel production and climate change threaten a successful outcome.

Anthropogenic emissions of greenhouse gases have led to an increase in radiative forcing (IPCC 2007). These emissions are dominated by carbon dioxide (CO₂) sources as a result of fossil fuel use and land use change, however, the primary sources of methane (CH₄) and nitrous oxide (N₂O) are derived from agricultural operations (IPCC 2007). While agriculture needs to continue research into fully understanding and mitigating its greenhouse gas emission processes there is also a significant opportunity for agricultural systems to sequester carbon into the soil and offset CO₂ emissions. For example, placing biochar into agricultural soils to offset greenhouse gas emissions has significant potential (Woolf et al.2010). Other carbon sequestration opportunities for agriculture include trying to develop technologies that can sequester carbon in soil by increasing the amount of soil organic carbon, its stabilization and depth distribution (Lal 2004).

With the global supply of readily available conventional oil peaking, concurrently, with the need to decrease fossil fuel CO₂ emissions (Hansen et al. 2008) alternative non-fossil fuel energy sources are sought. Biofuels provide one such option. Production of biofuels, based on agricultural commodities, increased 3-fold between 2000 and 2008 and by 2020 it is estimated that 13, 15 and 30% of the global production of coarse grain, vegetable oil and sugar cane will be used in biofuel production, respectively (2011). The immediate result of such a trend in biofuel production is competition between fuel and food for land and water resources, and in the case of previously unfarmed areas of land, the potential to increase water pollution through the use of pesticides and fertilisers (Searchinger and Heimlich 2009). While the use of second-generation non-food biomass biofuel feedstocks based on lignocelluloses will remove some food issues, it may still create competition for land and water resources.

Domestic water consumption globally accounts for an average 8% of the annual fresh water withdrawals, and this will increase with population growth. In many countries agriculture makes up 70–90% of the annual fresh water demand and its use in agriculture is coming under increasing scrutiny (Gilbert 2010; Grimwood2010). This has reached the point where water ‘footprints’ are being calculated for agricultural products along similar lines to carbon footprints. The agricultural demand for water in some countries has created a new ‘virtual water’ trade where developed countries (e.g. China, India, South Korea and Saudi Arabia) lease land abroad (e.g. sub-Saharan Africa, Madagascar) and grow food using the water that other countries don't have the means to exploit (Suweis et al.2011; Walt 2008).

Footprinting of agricultural products has implications for agricultural trade and requires that agricultural systems optimise product yields based on the lowest inputs of water and nutrients while minimising outputs of greenhouse gases and environmental degradation via nutrient and pesticide losses.

The current world population has been achieved largely thanks to the Haber-Bosch process which converts dinitrogen, in air, into chemically reactive ammonia, which can then be used in fertiliser manufacture. Erisman et al. (2008) estimate that, between 1908 and 2006, the number of humans supported by a hectare of arable land has increased from 1.9 to 4.3 persons, respectively, as a result of the Haber-Bosch process. This is, however, an energy intensive process using about 1% of the global primary energy supply (Erisman et al. 2008), so the price and use of fertiliser N is linked to, and highly sensitive to, prices on energy markets (OECD-FAO2011). Unfortunately, this hasn't stopped global average nitrogen use efficiencies from decreasing, which for cereals has decreased from −80% in 1960 to −30% in 2000 (Erisman et al. 2008). Only 17 Tg of the 100 Tg of N produced by the Haber-Bosch process in 2005 was actually consumed by humans in agricultural products (Erisman et al. 2008). The leakage of reactive N from agricultural systems results in N cascading through environmental reservoirs and increases in water and air pollution, greenhouse gas emissions and a loss of biodiversity (Galloway et al. 2003). While the stock source of N is plentiful for reactive N production this is not true of all fertilisers required in agriculture. For example, Cordell et al. (2009) put the case for acknowledging and planning for phosphorus (P) scarcity in the long-term with respect to global food security. This has raised concern to the point where some countries are considering the classification of P as a ‘strategic material’ (Elser and Bennett2011). But despite the looming reduction in phosphate reserves, similar to the N cycle, humanity has increased the environmental flow of P. In 2005 only 3 million tonnes of the 14 million tonnes used in fertilizer was consumed, with large losses (8 million tonnes) due to leaching and soil erosion (Cordell et al. 2009).

Resources for agricultural production (e.g. water, nutrients, and energy) are not evenly distributed around the planet which, in addition to climate variability inducing droughts, floods and fires, leads to volatility in trade and prices. The world has recently experienced its 5^th straight year of ‘high and volatile’ commodity prices (OECD-FAO2011). Such volatility also impacts upon food security and the wider economy in both developed and developing countries and there is a clear need for economic research into the causes and solutions to price volatility.

Agricultural research must deal with more than just ‘single issues’. Global agricultural issues are intrinsically linked to each other and the wellbeing of the global population. Attention must be paid to resource allocation and the intensification of environmentally sustainable production. While some countries will be able to use existing technologies to increase productivity there must also be, in addition to these, scientific advances in the efficiencies of water, fertilizer and pesticide use. This will require further investment in agricultural research, which currently only equates to approximately 5% of the total research and development spending on science worldwide (Nature News2010). So is there a critical issue facing agricultural research? Clearly there is not just one but a series of interwoven challenges that must ultimately be addressed concurrently.

Prof. Tim Clough

Lincoln University