Modeling the impacts of climate change on nitrogen losses and crop yield in a subsurface drained field (original) (raw)
Related papers
Agricultural Systems, 2018
Accurately predicting the impacts of higher temperatures, different precipitation rates and elevated CO 2 concentrations on crop yields and GHG emissions is required in order to develop adaptation strategies. The objectives of this study were to calibrate and evaluate a regionalized denitrification-decomposition (DNDC) model using measured crop yield, soil temperature, moisture and N 2 O emissions, and to explore the impacts of climate change scenarios (Representative Concentration Pathways (RCP) 4.5 and RCP 8.5) on crop yields and N 2 O emissions in Southwestern Ontario, Canada. This simulation study was based on a winter wheat-maize-soybean rotation under conventional tillage (CT) and no tillage (NT) practices at Woodslee, Ontario, Canada. The model was calibrated using various statistics including the d index (0.85-0.99), NSE (Nash-Sutcliffe efficiency, NSE N 0) and nRMSE (normalized root mean square error, nRMSE b 10%) all of which provided "good" to "excellent" agreement between simulated and measured crop yields for both CT and NT practices. The calibrated DNDC model had a "good" performance in assessing soil temperature. However, there were no differences in simulated soil temperatures between CT and NT treatments and this was attributed to deficiencies in the temperature algorithm which does not consider the insulation effect of surface crop residues in the DNDC model. The DNDC model provided a reasonable prediction of soil water content in the 0-0.1 m depth, but it overestimated soil water content during dry conditions mainly because the model was unable to characterize preferential flow through clay cracks. Under future climate scenarios, soybean and maize yields were significantly increased compared to the baseline scenarios due to the benefits from higher optimum temperature for maize and increased CO 2 for soybean. The mean annual N 2 O emissions for winter wheat significantly increased by about 38.1% for CT and 17.3% for NT under future RCP scenarios when using the current crop cultivars. However, when a new cultivar with higher TDD (thermal degree days) was used, the mean winter wheat yield increased by 39.5% under future climate scenarios compared to current cultivars and there were significant reductions in N 2 O emissions. The higher crop heat units cultivars and longer growing season length would contribute to increased biomass accumulation and crop N uptake. Hence there would be co-benefits with the development of high TDD cultivars in the future as they would not only increase crop yields but also reduce N 2 O emissions.
Projecting corn and soybeans yields under climate change in a Corn Belt watershed
Agricultural Systems, 2017
Climate change may have positive or negative effects on agricultural yields depending on location and mitigation and adaptation practices. This research investigates future corn and soybean yields in the Raccoon watershed, in the US Corn Belt, using projected climate data. We used the Environmental Policy Integrated Climate (EPIC) model to estimate the impact of climate change for 2015-2099 with data downscaled from eight atmosphere-ocean general circulation models (AOGCMs) with three emissions pathways reflecting low, medium and high greenhouse gas emissions scenarios. Soil properties were gathered from the Soil Survey Geographic Database and data on crop rotations was derived from CropScape, a geospatial cropland data layer product of the US National Agricultural Statistics Service (NASS). Our findings indicate that 20-year mean yields of both corn and soybean for 2080-2099 simulated in EPIC using all eight AOGCMs under low and medium carbon scenarios will increase in comparison to the 20-year mean yields for 2015-2034. However, under the high carbon scenario, 20-year means of both corn and soybean yields for 2080-2099 will decline in comparison to the 20-year mean yields for 2015-2034, pointing to the effects of climate change. We also examined the possible impact of carbon fertilization on yields. Our results show that carbon fertilization of soybean, a C 3 plant, may contribute to an increase in yield of 2% to 20% while its contribution to the growth of corn, a C 4 plant, will be much lower.
Modeling the impacts of climate change on nitrogen retention in a 4th order stream
Climatic Change, 2012
The effect of climate change on crop production and nitrate-nitrogen (NO 3 -N) pollution from subsurface drained fields is of a great concern. Using the calibrated and validated RZWQM2 (coupled with CERES-Maize and CROPGRO in DSSAT), the potential effects of climate change and elevated atmospheric CO 2 concentrations (CO 2 ) on tile drainage volume, NO 3 -N losses, and crop production were assessed integrally for the first time for a corn-soybean rotation cropping system near Gilmore City, Iowa. RZWQM2 simulated results under 20-year observed historical weather data (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009) and ambient CO 2 were compared to those under 20-year projected future meteorological data (2045-2064) and elevated CO 2 , with all management practices unchanged. The results showed that, under the future climate, tile drainage, NO 3 -N loss and flow-weighted average NO 3 -N concentration (FWANC) increased by 4.2 cm year −1 (+14.5 %), 11.6 kg N ha −1 year −1 (+33.7 %) and 2.0 mg L −1 (+ 16.4 %), respectively. Yields increased by 875 kg ha −1 (+28.0 %) for soybean [Glycine max (L.) Merr.] but decreased by 1380 kg ha −1 (−14.7 %) for corn (Zea mays L.). The yield of the C 3 soybean increased mostly due to CO 2 enrichment but increased temperature had negligible effect. However, the yield of C 4 corn decreased largely because of fewer days to physiological maturity due to increased temperature and limited benefit of elevated CO 2 to corn yield under subhumid climate. Relative humidity, short wave radiation and wind speed had small or negligible impacts on FWANC or grain yields. With the predicted trend, this study suggests that to mitigate NO 3 -N pollution from subsurface drained corn-soybean field in Iowa is a more challenging task in the future without changing current management practices. This study also demonstrates the advantage of an agricultural system model in assessing climate change Climatic Change
Modeling the impacts of climate change on irrigated corn production in the Central Great Plains
2012
The changes in temperature and precipitation patterns along with increasing levels of atmospheric carbon dioxide (CO 2 ) may change evapotranspiration (ET) demand, and affect water availability and crop production. An assessment of the potential impact of climate change and elevated CO 2 on irrigated corn (Zea mays L.) in the Central Great Plains of Colorado was conducted using the Root Zone Water Quality Model (RZWQM2) model. One hundred and twelve bias corrected and spatially disaggregated (BCSD) climate projections were used to generate four different multi-model ensemble scenarios of climate change: three of the ensembles represented the A1B, A2, and B1 emission scenarios and the fourth comprised of all 112 BCSD projections. Three different levels of irrigation, based on meeting 100, 75, and 50% of the crop ET demand, were used to study the climate change effects on corn yield and water use efficiency (WUE) under full and deficit irrigation. Predicted increases in mean monthly temperature during the crop growing period varied from 1.4 to 1.9, 2.1 to 3.4, and 2.7 to 5.4 • C during the 2020s, 2050s, and 2080s, respectively, for the different climate change scenarios. During the same periods, the projected changes in mean monthly precipitation varied in the range of −4.5 to 1.7, −6.6 to 4.0 and −11.5 to 10.2%, respectively. Simulation results showed a decrease in corn yield, because the negative effects of increase in temperature dominated over the positive effects of increasing CO 2 levels. The mean overall decrease in yield for the four different climate change scenarios, with full irrigation, ranged from 11.3 to 14.0, 17.1 to 21.0, and 20.7 to 27.7% during the 2020s, 2050s, and 2080s, respectively, even though the CO 2 alone increased yield by 3.5 to 12.8% for the scenario representing ensembles of 112 projections (S1). The yield decrease was linearly related to the shortening of the growing period caused by increased temperature. Under deficit irrigation, the yield decreases were smaller due to increased WUE with elevated CO 2 . Because of the shortened crop growing period and the CO 2 effect of decreasing the ET demand, there was a decrease in the required irrigation. Longer duration cultivars tolerant to higher temperatures may be one of the possible adaptation strategies. The amount of irrigation water needed to maintain the current yield for a longer duration corn cultivar, having the same WUE as the current cultivar, is projected to change in the range of −1.7 to 6.4% from the current baseline, under the four different scenarios of climate change evaluated in this research.
Soil & Tillage Research, 2017
The estimation of the GHG balance of agroecosystems is essential to evaluate the impact of agriculture on the composition of the atmosphere. Cultivated soils may act as a sink or a source of CO 2 and usually emit N 2 O. The aim of the present study was to assess the CO 2 and N 2 O balances, and to analyze the relationships between N 2 O fluxes and environmental variables for two soybean growing seasons and the fallow period between them, in an agricultural field in the Pampas region of Argentina. The fluxes of CO 2 and N 2 O were measured by the eddy covariance and the static-chamber methods, respectively. The net ecosystem exchange from sowing to harvest was À2543 and À2307 kg CO 2-C ha À1 , for the first and second growing seasons, respectively. The N 2 O net balance over the same periods was 1.45 and 0.96 kg N 2 ON ha À1. A multivariate analysis showed that during the growing season the most important variable influencing N 2 O emission was % water filled pore space (% WFPS), followed by nitrate content and soil temperature. During fallow, soil temperature was the main control factor, followed by % WPFS. The total balance (including CO 2 and N 2 O) showed that the soil gained 753.5 kg Ceq ha À1 on average during cultivarion cycle. Taking into account the fallow period, the global balance resulted in a carbon loss of 1328.5 kg Ceq ha À1 over about one year. Our results clearly indicate the need to incorporate winter cover crops for improving the production system, as they can provide carbon to the soil and use the available stubble nitrogen from the previous crop.
Global Change Biology, 2013
The physiological response of vegetation to increasing atmospheric carbon dioxide concentration ([CO 2 ]) modifies productivity and surface energy and water fluxes. Quantifying this response is required for assessments of future climate change. Many global climate models account for this response; however, significant uncertainty remains in model simulations of this vegetation response and its impacts. Data from in situ field experiments provide evidence that previous modeling studies may have overestimated the increase in productivity at elevated [CO 2 ], and the impact on large-scale water cycling is largely unknown. We parameterized the Agro-IBIS dynamic global vegetation model with observations from the SoyFACE experiment to simulate the response of soybean and maize to an increase in [CO 2 ] from 375 ppm to 550 ppm. The two key model parameters that were found to vary with [CO 2 ] were the maximum carboxylation rate of photosynthesis and specific leaf area. Tests of the model that used SoyFACE parameter values showed a good fit to site-level data for all variables except latent heat flux over soybean and sensible heat flux over both crops. Simulations driven with historic climate data over the central USA showed that increased [CO 2 ] resulted in decreased latent heat flux and increased sensible heat flux from both crops when averaged over 30 years. Thirty-year average soybean yield increased everywhere (ca. 10%); however, there was no increase in maize yield except during dry years. Without accounting for CO 2 effects on the maximum carboxylation rate of photosynthesis and specific leaf area, soybean simulations at 550 ppm overestimated leaf area and yield. Our results highlight important model parameter values that, if not modified in other models, could result in biases when projecting future crop-climate-water relationships.
Environmental Modelling & Software, 2001
A modeling approach was utilized to investigate the impact of increased atmospheric CO 2 and temperature on water balance, crop production, plant growth, and soil erosion. For the given scenario and the site tested, the increase of temperature resulted in a significant increase of ET, reduction of soybean canopy cover and yield, a slight increase in soil loss, and a reduction in soil moisture. However, the increase of atmospheric CO 2 resulted in significant increase of crop yield and canopy cover, a slight reduction of ET, and a slight reduction of daily root zone soil moisture, storm runoff, and water induced soil erosion of the corn field. Published by
Measurement of Net Global Warming Potential in Three Agroecosystems
Nutrient Cycling in Agroecosystems, 2005
When appraising the impact of food and fiber production systems on the composition of the Earth's atmosphere and the 'greenhouse' effect, the entire suite of biogenic greenhouse gases -carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) -needs to be considered. Storage of atmospheric CO 2 into stable organic carbon pools in the soil can sequester CO 2 while common crop production practices can produce CO 2 , generate N 2 O, and decrease the soil sink for atmospheric CH 4 . The overall balance between the net exchange of these gases constitutes the net global warming potential (GWP) of a crop production system. Trace gas flux and soil organic carbon (SOC) storage data from long-term studies, a rainfed site in Michigan that contrasts conventional tillage (CT) and no-till (NT) cropping, a rainfed site in northeastern Colorado that compares cropping systems in NT, and an irrigated site in Colorado that compares tillage and crop rotations, are used to estimate net GWP from crop production systems. Nitrous oxide emissions comprised 40-44% of the GWP from both rain-fed sites and contributed 16-33% of GWP in the irrigated system. The energy used for irrigation was the dominant GWP source in the irrigated system. Whether a system is a sink or source of CO 2 , i.e. net GWP, was controlled by the rate of SOC storage in all sites. SOC accumulation in the surface 7.5 cm of both rainfed continuous cropping systems was approximately 1100 kg CO 2 equivalents ha À1 y À1 . Carbon accrual rates were about three times higher in the irrigated system. The rainfed systems had been in NT for >10 years while the irrigated system had been converted to NT 3 years before the start of this study. It remains to be seen if the C accrual rates decline with time in the irrigated system or if N 2 O emission rates decline or increase with time after conversion to NT.