作者
Peng Zhang,Iseult Lynch,Richard D. Handy,Jason C. White
摘要
Agriculture is always the most important sector of global economies because humans rely on the food produced by agriculture to survive. According to the World Bank, in 2018 agriculture accounted for 4% of global gross domestic product (GDP) and in some of the least developed countries, it can account for more than 25% of GDP. Historically, agriculture has undergone three revolutions, each of which brought tremendous increases in agricultural production. The first was the transition from hunting/gathering to settled agriculture, and the second was the transition from hand production methods to use of machinery, improved drainage, and introduction of plant breeding and crop rotation for example. The third revolution, also known as the green revolution, which occurred in the 1930s–60s, resulted in significant increase of agricultural production and contributed to widespread reduction of poverty and hunger, as a result of the use of chemical fertilizers, agrochemicals, and controlled water supply (usually involving irrigation) coupled with newer methods of cultivation and the development of more resilient crop breeds, including genetically modified crops. The green revolution is estimated to have increased agriculture yields by 44% between 1965 and 2010. However, the world population has grown by more than 5 billion since the beginning of the green revolution, which has necessitated a continuous growth in crop production. It is projected that global populations will further increase by one-third by 2050 and as such will require a 70% increase of food production compared to current output. Feeding so many people using limited natural resources (land, water, and soil), and in the face of declining soil quality, is a grand challenge that the agriculture sector today is facing. It is estimated that nearly 2 billion hectares of soil resources in the world have been degraded, accounting for approximately 22% of the total cropland, pasture, forest, and woodland, as a result of soil erosion, chemical deterioration, and physical degradation which are accelerated by human activities such as inappropriate agricultural management, overgrazing, and deforestation. Degraded soil means less food—estimations are that 11.9%–13.4% of the global agricultural supply has been lost in the past five decades. Moreover, climate change arising from increasing atmospheric CO2 concentration leading to rising temperature is likely to further affect the resilience of agricultural soils and their ability to sustain productivity and ensure food security for an increasing human population. These challenges require an urgent alteration of the current agriculture.