In the context of global warming and human interventions, the impact of climate on crop yield may change over time. Therefore, assessing the dynamics of drought thresholds that trigger various maize ...yield losses is critical for food security under climate change. To this end, this study aims to assess the vulnerability of maize to drought stress in three provinces of Northeast China (Heilongjiang, Jilin and Liaoning provinces) and to quantify the drought thresholds that cause different levels of maize yield loss. A Copula-Bayesian conditional probability bivariate model is constructed to combine drought conditions and maize yield. Results indicate that: (1) for the whole study period 1980–2018, drought thresholds that induced different levels of maize yield reduction were significantly different in the three northeastern provinces of China; on average, the drought thresholds that induced 30%, 40% and 50% maize yield losses were −1.06, −1.53 and −2.23 in the three provinces of Northeast China; (2) during the transition from mild to moderate and severe drought, maize vulnerability in Liaoning province gradually exceeded that of Jilin and Heilongjiang province; (3) from 1980 to 1999–2000–2018, the drought thresholds that triggered the same percentage of maize yield reduction increased in all three provinces, suggesting a dramatically increasing trend in the vulnerability of maize yields to drought; (4) the changes in precipitation and evapotranspiration leading to increased drought severity were the main factors inducing drought threshold dynamics in both sub-study periods. The probabilistic assessment of the impact of drought on maize yield is expected to provide useful insights into the mitigation of drought and its effects under climate change.
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•The vulnerability of maize yield to various drought stresses was assessed.•Drought thresholds triggering various maize yield loss were quantified.•The average drought thresholds resulting in 30%, 40% and 50% maize losses were −1.06, −1.53 and −2.23.•Increasing drought thresholds were mainly caused by precipitation and ET dynam-ics.
We analyze trends in crop yields and yield variability of barley, maize, oats, rye, triticale and wheat in Switzerland from 1961 to 2006. It shows that there have been linear increases in crop yields ...since the 1960s. However, yields of barley, oats, rye, triticale and wheat have leveled off in Switzerland since the early 1990s, which contrasts linear trends in cereal yields that is usually assumed for Europe. We show a relationship between the introduction of agricultural policy measures towards environmentally friendly cereal production that fostered widespread adoption of extensive farming practices and the observed leveling-off of crop yields. Thus, this paper emphasizes that agricultural policy can be an important reason for slowing crop yield growth. Agricultural policy measures will be one of the key driving forces of future crop yields. Thus, the potential leveling-off of crop yields that is indicated in this study should be considered in analyses of future land use and food supply as well as in the evaluation of agri-environmental measures and policy reforms.
Agriculture in 2050 HUNTER, MITCHELL C.; SMITH, RICHARD G.; SCHIPANSKI, MEAGAN E. ...
Bioscience,
04/2017, Volume:
67, Issue:
4
Journal Article
Peer reviewed
Open access
The prevailing discourse on the future of agriculture is dominated by an imbalanced narrative that calls for food production to increase dramatically—potentially doubling by 2050—without specifying ...commensurate environmental goals. We aim to rebalance this narrative by laying out quantitative and compelling midcentury targets for both production and the environment. Our analysis shows that an increase of approximately 25%–70% above current production levels may be sufficient to meet 2050 crop demand. At the same time, nutrient losses and greenhouse gas emissions from agriculture must drop dramatically to restore and maintain ecosystem functioning. Specifying quantitative targets will clarify the scope of the challenges that agriculture must face in the coming decades, focus research and policy on achieving specific outcomes, and ensure that sustainable intensification efforts lead to measurable environmental improvements. We propose new directions for research and policy to help meet both sustainability and production goals.
The potential impacts of climate change on crop productivity are of widespread interest to those concerned with addressing climate change and improving global food security. Two common approaches to ...assess these impacts are process-based simulation models, which attempt to represent key dynamic processes affecting crop yields, and statistical models, which estimate functional relationships between historical observations of weather and yields. Examples of both approaches are increasingly found in the scientific literature, although often published in different disciplinary journals. Here we compare published sensitivities to changes in temperature, precipitation, carbon dioxide (CO2), and ozone from each approach for the subset of crops, locations, and climate scenarios for which both have been applied. Despite a common perception that statistical models are more pessimistic, we find no systematic differences between the predicted sensitivities to warming from process-based and statistical models up to +2 °C, with limited evidence at higher levels of warming. For precipitation, there are many reasons why estimates could be expected to differ, but few estimates exist to develop robust comparisons, and precipitation changes are rarely the dominant factor for predicting impacts given the prominent role of temperature, CO2, and ozone changes. A common difference between process-based and statistical studies is that the former tend to include the effects of CO2 increases that accompany warming, whereas statistical models typically do not. Major needs moving forward include incorporating CO2 effects into statistical studies, improving both approaches' treatment of ozone, and increasing the use of both methods within the same study. At the same time, those who fund or use crop model projections should understand that in the short-term, both approaches when done well are likely to provide similar estimates of warming impacts, with statistical models generally requiring fewer resources to produce robust estimates, especially when applied to crops beyond the major grains.
Extreme heat stress during the crop reproductive period can be critical for crop productivity. Projected changes in the frequency and severity of extreme climatic events are expected to negatively ...impact crop yields and global food production. This study applies the global crop model PEGASUS to quantify, for the first time at the global scale, impacts of extreme heat stress on maize, spring wheat and soybean yields resulting from 72 climate change scenarios for the 21st century. Our results project maize to face progressively worse impacts under a range of RCPs but spring wheat and soybean to improve globally through to the 2080s due to CO2 fertilization effects, even though parts of the tropic and sub-tropic regions could face substantial yield declines. We find extreme heat stress at anthesis (HSA) by the 2080s (relative to the 1980s) under RCP 8.5, taking into account CO2 fertilization effects, could double global losses of maize yield (ΔY = −12.8 ± 6.7% versus − 7.0 ± 5.3% without HSA), reduce projected gains in spring wheat yield by half (ΔY = 34.3 ± 13.5% versus 72.0 ± 10.9% without HSA) and in soybean yield by a quarter (ΔY = 15.3 ± 26.5% versus 20.4 ± 22.1% without HSA). The range reflects uncertainty due to differences between climate model scenarios; soybean exhibits both positive and negative impacts, maize is generally negative and spring wheat generally positive. Furthermore, when assuming CO2 fertilization effects to be negligible, we observe drastic climate mitigation policy as in RCP 2.6 could avoid more than 80% of the global average yield losses otherwise expected by the 2080s under RCP 8.5. We show large disparities in climate impacts across regions and find extreme heat stress adversely affects major producing regions and lower income countries.
Current agriculture faces multiple challenges due to rapid increases in food demand and environmental concerns. Recently, biochar application in agricultural soils has attracted a good deal of ...attention. According to literature findings, biochar has proven to play various beneficial roles with respect to the enhancement of crop yield as a fertilizer and soil quality as a soil conditioner. It can further be used to remediate soil pollution as an adsorbent, while supporting the mitigation of greenhouse gases (GHGs) through the expansion of the soil carbon pool. The efficacy of biochar application on agricultural environments is found to be controlled by various factors such as pyrolysis temperature, feed stock, soil type, and biotic interactions. The combined effects of these factors may thus exert a decisive control on the overall outcome. Furthermore, the biochar application can also be proven to be detrimental in some scenarios. This review evaluates both the potential benefits and limitations of biochar application in agriculture soils.
•Biochar-amended soils have promise in agro-environments due to the unique physiochemical characteristics of biochar.•Biochar has been proven to improve the yield, nutrition and management of disease and stress in plants.•Addition of biochar to soil can decrease emissions of GHGs (CO2 and CH4) from agriculture.•Potential limitations of biochar in agricultural soils must be taken into consideration prior its utilization.
Long-term exposure of food crops to high concentrations of ambient ozone (O3) can cause significant yield reductions. O3-induced crop loss studies are limited in China, especially in the North China ...Plain (NCP) where agricultural resources are abundant and O3 concentrations are high. In this study, we quantify the O3-induced adverse impacts on wheat and maize over the NCP and Shanxi province during 2013–2018 through the use of high-resolution air quality reanalysis dataset and land-use dataset. Results show that the accumulated hourly O3 concentration above 40 ppb (AOT40) in croplands experienced an upward trend, with an annual increase of 2.2 ppm h (18.1%) during the wheat growing period and 1.5 ppm h (10.9%) during the maize growing period from 2013 to 2018. O3-induced relative yield losses grew from 17.9% in 2013 to 38.6% in 2018 for wheat, and ranged from 7.5 to 11.9% for maize. The estimated crop production losses also increased over time. Shandong and Hebei provinces are the hot spots of crop losses and priorities should be given to them for O3 pollution prevention. Comparison with previous studies shows that uncertainties still exist in crop loss estimations. More rural O3 measurements and localized crop exposure-response experiments should be performed for better assessments.
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•Crop yield losses were estimated using high-resolution air quality reanalysis data and land use data.•Crop losses in northern China increased with time.•Hot spots of crop losses in northern China were determined.
Water is a major factor limiting crop production in many regions around the world. Irrigation can greatly enhance crop yields, but the local availability and timing of freshwater resources constrains ...the ability of humanity to increase food production. Innovations in irrigation infrastructure have allowed humanity to utilize previously inaccessible water resources, enhancing water withdrawals for agriculture while increasing pressure on environmental flows and other human uses. While substantial additional water will be required to support future food production, it is not clear whether and where freshwater availability is sufficient to sustainably close the yield gap in cultivated lands. The extent to which irrigation can be expanded within presently rainfed cropland without depleting environmental flows remains poorly understood. Here we perform a spatially explicit biophysical assessment of global consumptive water use for crop production under current and maximum attainable yield scenarios assuming current cropping practices. We then compare these present and anticipated water consumptions to local water availability to examine potential changes in water scarcity. We find that global water consumption for irrigation could sustainably increase by 48% (408 km3 H2O yr−1)-expanding irrigation to 26% of currently rainfed cultivated lands (2.67 × 106 km2) and producing 37% (3.38 × 1015 kcal yr−1) more calories, enough to feed an additional 2.8 billion people. If current unsustainable blue water consumption (336 km3 yr−1) and production (1.19 × 1015 kcal yr−1) practices were eliminated, a sustainable irrigation expansion and intensification would still enable a 24% increase in calorie (2.19 × 1015 kcal yr−1) production. Collectively, these results show that the sustainable expansion and intensification of irrigation in selected croplands could contribute substantially to achieving food security and environmental goals in tandem in the coming decades.
Wheat is the second most important direct source of food calories in the world. After considerable improvement during the Green Revolution, increase in genetic yield potential appears to have ...stalled. Improvement of photosynthetic efficiency now appears a major opportunity in addressing the sustainable yield increases needed to meet future food demand. Effort, however, has focused on increasing efficiency under steady-state conditions. In the field, the light environment at the level of individual leaves is constantly changing. The speed of adjustment of photosynthetic efficiency can have a profound effect on crop carbon gain and yield. Flag leaves of wheat are the major photosynthetic organs supplying the grain of wheat, and will be intermittently shaded throughout a typical day. Here, the speed of adjustment to a shade to sun transition in these leaves was analysed. On transfer to sun conditions, the leaf required about 15 min to regain maximum photosynthetic efficiency. In vivo analysis based on the responses of leaf CO2 assimilation (A) to intercellular CO2 concentration (ci) implied that the major limitation throughout this induction was activation of the primary carboxylase of C3 photosynthesis, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). This was followed in importance by stomata, which accounted for about 20% of the limitation. Except during the first few seconds, photosynthetic electron transport and regeneration of the CO2 acceptor molecule, ribulose-1,5-bisphosphate (RubP), did not affect the speed of induction. The measured kinetics of Rubisco activation in the sun and de-activation in the shade were predicted from the measurements. These were combined with a canopy ray tracing model that predicted intermittent shading of flag leaves over the course of a June day. This indicated that the slow adjustment in shade to sun transitions could cost 21% of potential assimilation.
This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.
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