Three new publications investigate proposed solutions to global food insecurity, exploring the potential consequences of liberalising trade, increasing crop yields and introducing biotechnology. The first, written by agricultural scientists Tony Fisher, Derek Byerlee and Greg Edmeades, Crop Yields and Global Food Security, investigates the rate at which crop yields must increase if we are to meet global demand for staple crops by 2050. They explore how such targets might be achieved and what the consequences would be for the environment and natural resources.
Population growth, rising incomes per capita and growing biofuel usage mean we expect demand for staple crop products to increase by 60% between 2010 and 2050. This increase can either be met by expanding land area under agriculture or by increasing the yields of crops grown on current land. With land being in short supply and much potential agricultural land requiring deforestation and natural habitat clearance, the latter option has far more support. Indeed crop area is expected to grow only 10% between 2010 and 2050, with some of this increase originating from increased cropping intensity. To date yields of wheat, rice and soybean have been steadily rising over the past 20 years. The rate of growth, however has been declining and wheat yields are increasing at approximately 1% each year compared to 2010 figures (1.5% for maize). Crop models tell us that if we are to meet future demand and keep food prices at less than 30% higher than the low prices of 2000-2006 then yields of staple crops must rise by 1.1% each year. Of course these figures do not take into account the other resource challenges agriculture faces, climate change or tackling hunger and thus authors suggest a higher rate of increase of 1.3% per annum.
The book explains key concepts in crop physiology and yield, for example, a term often used when discussing agriculture in developing countries, “closing the yield gap”. The yield gap is effectively the difference between the yields obtained on a farm (Farm Yield or FY) and the yields obtained under field trial conditions (Potential Yield or PY). For wheat, although the book also explores other staple crops, the yield gap is on average around 48% of the FY. This varies by location with developing countries (and crops produced under rainfed conditions) showing a larger gap and Western Europe showing the smallest gap, some 30%. Progress towards closing this gap is worryingly slow, occurring at a global average rate of just 0.2% per year, and in Western Europe may actually be increasing. Yield gaps are difficult to close and on average closing a yield gap by 10% of FY takes some 20 years. Here authors highlight the difficulty of increasing Farm Yields through technology adoption and improved agronomic practices, and the importance of increasing PY to stimulate Farm Yield gains, likely through improved varieties.
Addressing these yield gaps, authors say, will require a combination of plant breeding of higher yielding and more resilient varieties, public agricultural extension to train farmers in improved farming practices and greater integration between farmers, scientists and businesses. While examples of yield gaps being significantly closed do exist, particularly where new technologies are adopted and markets are reliable – the One Acre Fund being given as an example, the rural transformation required to help subsistence farmers in developing countries close the gap will require substantial investment that as yet is missing. [Read more…]
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