The Efficiency Dilemma in the Intensifying Crop Production System Around the World
Abstract
Land and nitrogen (N) are two critical resources in crop productivity. However, since 1961, while yield (a measure of land use efficiency) has increased from 70 kg N ha-1 yr-1 to 110 kg N ha-1 yr-1 globally, N use efficiency (i.e. yield per unit N input) has decreased from 68% to approximately 47%. Understanding the causes of these differences in efficiency is essential for developing N management strategies to address the dual challenges of food security and N pollution.
We developed a N budget database for 113 countries worldwide for the period of 1975-2010, and examined the relationship among N input, NUE and yield. We applied a least square regression model to examine the relationship between N fertilization rate (kg N fertilizer per hectare) and N use efficiency, while we applied a typical form of yield response function (i.e. hyperbolic tangent function) to examine yield response to increasing N fertilization rate. Our preliminary results show that, for most countries, NUE follows a U-shaped trajectory as N fertilization rate increases, suggesting that yield increases are driven by increasing fertilization at the initial intensification stage of crop production. However, without improvement in technology and management practices (TMPs), NUE tends to decrease with increased N fertilization rate and yield due to the diminishing return of yield response to N inputs. Implementation of TMPs for yield improvement or reduction in N input could potentially reverse this issue. As countries intensify use of N fertilizer, the NUE occurs in different phases on the curve. We classify all the countries that show a statistically significant relationship between NUE and N fertilization rate into three groups according to the NUE phase that they are experiencing: continually decreasing, approaching the turning point, and gradually rising. Further investigation into those countries that can increase NUE along with yield will provide valuable insights such as N management practices or policies for other countries to address the dual challenges of food security and N pollution.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMED0260066W
- Keywords:
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- 0805 Elementary and secondary education;
- EDUCATION