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Lookup NU author(s): Professor Keith Syers, Dr John Lingard
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China has been able to feed a rapidly growing population by increasing crop yields, partly through the use of mineral fertilizers. Although now faced with a lower population growth rate, the prospects for increasing food production are uncertain because of the decline in the rate of increase in crop yields. This paper describes the use of a nutrient audit model to calculate nutrient output and input relationships, nutrient balances, and nutrient depletion rates between 1961 and 1997. Over the last two decades, China has been able to reduce its nitrogen (N) deficit through the use of large quantities of N fertilizers and has now achieved a balance. About 65% of total N inputs are supplied as N fertilizers. Significant progress has also been made in reducing the phosphorus (P) deficit from 1.2 million tonnes in 1985 to 0.6 million tonnes in 1997, when P fertilizer accounted for 57% of total P inputs. There is, however, a major annual depletion of potassium (K) which increased from 2.9 million tonnes in 1961 to 8.3 million tonnes in 1997. Potassium balances for the 30 provinces in China in 1996 indicate high depletion rates in all provinces. China has no large K reserves so most K fertilizers have to be imported. Application rates of K have remained relatively low and K fertilizer accounts for only 14% of total K inputs. This large and growing K deficit poses a major threat to China's future food production and K fertilizer use must be increased substantially to correct the resulting nutrient imbalance and minimize soil degradation. To increase annual food production growth rates by 1% and limit the annual K deficit to its current level of 8.3 million tonnes will require an average annual growth rate in K fertilizer consumption of more than 3% between 1997 and 2020. To achieve a balance of K by 2020 will require an increase in K fertilizer use of more than 8% per year. It is highly unlikely that this growth rate can be achieved and this will have serious long-term consequences for China. More work is needed using the nutrient audit model to relate food production to fertilizer needs. © 2002 Elsevier Science B.V. All rights reserved.
Author(s): Sheldrick WF, Syers JK, Lingard J
Publication type: Article
Publication status: Published
Journal: Agriculture, Ecosystems and Environment
Year: 2003
Volume: 94
Issue: 3
Pages: 341-354
Print publication date: 01/03/2003
ISSN (print): 0167-8809
ISSN (electronic): 1873-2305
Publisher: Elsevier
URL: http://dx.doi.org/10.1016/S0167-8809(02)00038-5
DOI: 10.1016/S0167-8809(02)00038-5
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