Abstract
Abstract. Spring wheat is a major food crop that is a staple for a large number of people in India and the world. To address the issue of food security, it is essential to understand how the productivity of spring wheat varies with changes in environmental conditions and agricultural management practices. The goal of this study is to quantify the role of different environmental factors and management practices on wheat production in India in recent years (1980 to 2016). Elevated atmospheric CO2 concentration ([CO2]) and climate change are identified as two major factors that represent changes in the environment. The addition of nitrogen fertilizers and irrigation practices are the two land management factors considered in this study. To study the effects of these factors on wheat growth and production, we developed crop growth processes for spring wheat in India and implemented them in the Integrated Science Assessment Model (ISAM), a state-of-the-art land model. The model is able to simulate the observed leaf area index (LAI) at the site scale and observed production at the country scale. Numerical experiments are conducted with the model to quantify the effect of each factor on wheat production on a country scale for India. Our results show that elevated [CO2] levels, water availability through irrigation, and nitrogen fertilizers have led to an increase in annual wheat production at 0.67, 0.25, and 0.26 Mt yr−1, respectively, averaged over the time period 1980–2016. However, elevated temperatures have reduced the total wheat production at a rate of 0.39 Mt yr−1 during the study period. Overall, the [CO2], irrigation, fertilizers, and temperature forcings have led to 22 Mt (30 %), 8.47 Mt (12 %), 10.63 Mt (15 %), and −13 Mt (−18 %) changes in countrywide production, respectively. The magnitudes of these factors spatially vary across the country thereby affecting production at regional scales. Results show that favourable growing season temperatures, moderate to high fertilizer application, high availability of irrigation facilities, and moderate water demand make the Indo-Gangetic Plain the most productive region, while the arid north-western region is the least productive due to high temperatures and lack of irrigation facilities to meet the high water demand.
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Claims 12
Claim · model-written summary
ISAM simulated observed leaf area index at site scale.
Verbatim
e0“The model is able to simulate the observed leaf area index (LAI) at the site scale”
Claim · model-written summary
ISAM simulated observed country scale production.
Verbatim
e0“observed production at the country scale”
Claim · model-written summary
Elevated CO2 increased annual wheat production by 0.67 Mt yr−1 over 1980–2016.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- elevated [CO2] levelse0
- Outcome
- annual wheat productione0
- Direction
- increasee0
- Value
- 0.67e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] levels, water availability through irrigation, and nitrogen fertilizers have led to an increase in annual wheat production at 0.67, 0.25, and 0.26 Mt yr−1, respectively, averaged over the time period 1980–2016”
Claim · model-written summary
Irrigation increased annual wheat production by 0.25 Mt yr−1.
- Taxon
- wheatTriticum aestivume0
- Treatment
- water availability through irrigatione0
- Outcome
- annual wheat productione0
- Direction
- increasee0
- Value
- 0.25e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] levels, water availability through irrigation, and nitrogen fertilizers have led to an increase in annual wheat production at 0.67, 0.25, and 0.26 Mt yr−1, respectively, averaged over the time period 1980–2016”
Claim · model-written summary
Nitrogen fertilizers increased annual wheat production by 0.26 Mt yr−1.
- Taxon
- wheatTriticum aestivume0
- Treatment
- nitrogen fertilizerse0
- Outcome
- annual wheat productione0
- Direction
- increasee0
- Value
- 0.26e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated [CO2] levels, water availability through irrigation, and nitrogen fertilizers have led to an increase in annual wheat production at 0.67, 0.25, and 0.26 Mt yr−1, respectively, averaged over the time period 1980–2016”
Claim · model-written summary
Elevated temperatures reduced wheat production by 0.39 Mt yr−1.
- Taxon
- wheatTriticum aestivume0
- Treatment
- elevated temperaturese0
- Outcome
- total wheat productione0
- Direction
- reducede0
- Value
- 0.39 Mt yr−1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated temperatures have reduced the total wheat production at a rate of 0.39 Mt yr−1 during the study period”
Claim · model-written summary
CO2 forcing changed countrywide wheat production by 22 Mt (30%).
Not reportedTaxonComparator
Verbatim
e0“the [CO2], irrigation, fertilizers, and temperature forcings have led to 22 Mt (30 %), 8.47 Mt (12 %), 10.63 Mt (15 %), and −13 Mt (−18 %) changes in countrywide production, respectively”
Claim · model-written summary
Irrigation forcing changed countrywide wheat production by 8.47 Mt (12%).
- Treatment
- irrigatione0
- Outcome
- countrywide productione0
- Direction
- increaseinferrede0
- Value
- 8.47 Mt (12 %)e0
Not reportedTaxonComparator
Verbatim
e0“the [CO2], irrigation, fertilizers, and temperature forcings have led to 22 Mt (30 %), 8.47 Mt (12 %), 10.63 Mt (15 %), and −13 Mt (−18 %) changes in countrywide production, respectively”
Claim · model-written summary
Fertilizer forcing changed countrywide wheat production by 10.63 Mt (15%).
- Treatment
- fertilizerse0
- Outcome
- countrywide productione0
- Direction
- increaseinferrede0
- Value
- 10.63 Mt (15 %)e0
Not reportedTaxonComparator
Verbatim
e0“the [CO2], irrigation, fertilizers, and temperature forcings have led to 22 Mt (30 %), 8.47 Mt (12 %), 10.63 Mt (15 %), and −13 Mt (−18 %) changes in countrywide production, respectively”
Claim · model-written summary
Temperature forcing changed countrywide wheat production by −13 Mt (−18%).
- Treatment
- temperaturee0
- Outcome
- countrywide productione0
- Direction
- decreaseinferrede0
- Value
- −13 Mt (−18 %)e0
Not reportedTaxonComparator
Verbatim
e0“the [CO2], irrigation, fertilizers, and temperature forcings have led to 22 Mt (30 %), 8.47 Mt (12 %), 10.63 Mt (15 %), and −13 Mt (−18 %) changes in countrywide production, respectively”
Claim · model-written summary
The Indo-Gangetic Plain was the most productive region.
Not reportedTaxon
Verbatim
e0“the Indo-Gangetic Plain the most productive region”
Claim · model-written summary
The arid north-western region was the least productive.
Not reportedTaxon
Verbatim
e0“the arid north-western region is the least productive due to high temperatures and lack of irrigation facilities to meet the high water demand”
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