Maize Belt Research Articles

Assessment of waterlogging hazard during maize growth stage in the Songliao plain based on daily scale SPEI and SMAI

Waterlogging is one of the major disasters affecting crop yield and food security. The Songliao Plain, located in the mid-latitude region and known as the "Golden Maize Belt," is severely impacted by waterlogging, which significantly affects maize yield. Therefore, it is essential to conduct a detailed assessment of the waterlogging hazard for maize in the Songliao Plain and to apply the results to agricultural meteorological disaster prevention and mitigation measures. In this study, a comprehensive waterlogging hazard assessment index was constructed by combining environmental factors conducive to disaster and disaster-causing factors. Environmental factors included terrain slope, distance from rivers, and soil clay content, while disaster-causing factors included daily SPEI and SMAI during the maize growing season in the Songliao Plain from 1982 to 2020. The results indicate that: (1) The spatial distribution of waterlogging hazard in the Songliao Plain ranges from extremely high to extremely low, showing a gradual decrease from west to east. The western and southern parts of the Songliao Plain, such as Baicheng, Songyuan, Changchun, and Fuxin, are more prone to waterlogging disasters. (2) During different maize growth stages, the spatial distribution of high and extremely high levels of waterlogging hazard exhibited significant heterogeneity. There were notable differences in the duration of waterlogging around the year 2000, with a reduction in the duration of extremely high and high levels of waterlogging after 2000. (3) A Pearson correlation analysis was conducted between the comprehensive waterlogging hazard index and SIF (Solar-Induced Fluorescence) data during different maize growth stages. The results showed a strong correlation between the comprehensive waterlogging hazard index and SIF data, with the highest correlation coefficient reaching −0.9 and a p-value less than 0.05. The comprehensive maize waterlogging hazard index can be used for precise and timely assessment of waterlogging hazard during different growth stages of maize, and it has a positive impact on improving the ability to prevent and mitigate waterlogging risks.

Construction and Application of Dynamic Threshold Model for Agricultural Drought Grades Based on Near-Infrared and Short-Wave Infrared Bands for Spring Maize

Maize (Zea mays L.) is one of the most important grain crops in the world. Drought caused by climate change in recent years may greatly threaten water supply and crop production, even if the drought only lasts for a few days or weeks. Therefore, effective daily drought monitoring for maize is crucial for ensuring food security. A pivotal challenge in current related research may be the selection of data collection and the methodologies in the construction of these indices. Therefore, orthorectified reflectance in the short-wave infrared (SWIR) band, which is highly sensitive to variations in vegetation water content, was daily obtained from the MODIS MCD43A4 product. Normalized Difference Water Index (NDWI) calculated using the NIR and SWIR bands and days after planting (DAP) were normalized to obtain the Vegetation Water Index (VWI) and normalized days after planting (NDAP), respectively. The daily dynamic threshold model for different agricultural drought grades was constructed based on the VWI and NDAP with double-logistic fitting functions during the maize growing season, and its specific threshold was determined with historical drought records. Verification results indicated that the VWI had a good effect on the daily agricultural drought monitoring of spring maize in the “Golden Maize Belt” in northeast China. Drought grades produced by the VWI were completely consistent with historical records for 84.6% of the validation records, and 96.2% of the validation records differed by only one grade level or less. The VWI can not only daily identify the occurrence and development process of drought, but also well reflect the impact of drought on the yield of maize. Moreover, the VWI could be used to monitor the spatial evolution of drought processes at both regional and precise pixel scales. These results contribute to providing theoretical guidance for the daily dynamic monitoring and evaluation of spring maize drought in the “Golden Maize Belt” of China.

33P‐isotope labelling ammonium phosphate fertilizers reveals majority of early growth maize phosphorus is soil‐derived

AbstractIn soils managed to have adequate to high Mehlich‐3 phosphorus (P) concentrations throughout the US Maize Belt, the majority of crop P is soil‐derived. Struvite, a low water solubility ammonium phosphate fertilizer, may be therefore substituted for relatively high water‐soluble monoammonium phosphate (MAP) without adversely impacting maize (Zea mays L.) P uptake and growth, while minimizing fertilizer P loss risk. We determined the relative contribution of struvite and MAP to maize P uptake and soil solution P in soils representative of the US Maize Belt by radiolabelling fertilizers with 33P. We found 8% (struvite) to 22% (MAP) of early‐to‐mid vegetative growth stage (V7) maize P was fertilizer‐derived, and thus, 78%–92% was soil‐derived. Despite similar aboveground P uptake and maize growth, maize P use efficiency (PUE) determined directly by 33P was <5% for MAP (4.9%) and struvite (1.9%) indicating that in soils with adequate to high crop‐available P, early season fertilizer PUE is relatively low. If prorated to harvest stage, in‐season PUE was estimated to be 8% for struvite and 20% for MAP. MAP and struvite did not differ in relative contributions to water‐extractable P, a proxy for P loss risk, potentially reflecting lag effects in struvite P dissolution and/or the relatively fine particle size of synthesized fertilizers (<0.1 mm diameter). Since maize aboveground biomass and P uptake were similar for both struvite and MAP, struvite could be an effective P fertilizer for soils with adequate to high Mehlich‐3 P concentrations common across the US Maize Belt.

Soil buffering capacity enhances maize yield resilience amidst climate perturbations

CONTEXTMaize production in China is facing a multitude of challenges such as climate change, increasing demand, and limited cropland availability. Soil properties, beyond supporting crop growth and development, can play a critical role in buffering the impacts of climate crisis on crop yields. However, little information is known about such buffering capacities and their spatial distributions of soil properties in buffering the impacts of climate perturbations on maize yields in China's maize belt (CMB). OBJECTIVEThe objective of this study was to identify the responses of different regions within the CMB to climate perturbations in terms of maize yields, as well as their spatial differences and magnitudes. Additionally, we aimed to quantify the capacities of soil properties in buffering the impacts of climate perturbations. METHODSWe quantified the impacts of climate perturbations (climate fluctuations deviating from the mean state) on maize yields using the APSIM across the China's maize belt. We then used the random forest model to interpret the buffering effects of typical soil properties to the adverse impacts of climate perturbations. RESULTS AND CONCLUSIONSOur results reveal that temperature variability was the predominant climatic perturbation affecting maize yields, with rising temperature leading to significant yield losses in most regions. Perturbations in solar radiation and precipitation exhibited relatively stronger positive yield impacts only in areas with inadequate solar radiation and dry conditions, respectively. Notably, soil properties explained ∼40% to ∼70% of the spatial variations for the impacts of climate perturbations. Soils with high soil organic carbon content (SOC) can significantly reduce the negative impacts of temperature increase, highlighting the crucial buffering effect of SOC in response to global warming. Soil texture, field capacity and bulk density were also critical soil buffering properties for interpreting the spatial patterns of the impacts of climate perturbations. SIGNIFICANCEOur results underscore the importance of soil quality improvement to ensure stable food production, which is an effective strategy for enhancing agricultural system resilience amidst future climate crises.

Sustainable maize intensification through site-specific nutrient management advice: Experimental evidence from Nigeria

There is growing evidence on the impacts of site-specific nutrient management (SSNM) from Asia. The evidence for Sub-Saharan Africa (SSA), where SSNM developments are more recent and where conditions concerning soil fertility and fertilizer use differ importantly from those in Asia, is extremely scarce. We evaluate a SSNM advisory tool that allows extension agents to generate fertilizer recommendations tailored to the specific situation of an individual farmer’s field, using a three-year randomized controlled trial with 792 smallholder farmers in the maize belt of northern Nigeria. Two treatment arms were implemented: T1 and T2 both provide SSNM information on nutrient use and management, but T2 provides additional information on maize price distributions and the associated variability of expected returns to fertilizer use. We estimate average and heterogenous intent-to-treat effects on agronomic, economic and environmental plot-level outcomes. We find that T1 and T2 lead to substantial increases (up to 116%) in the adoption of good fertilizer management practices and T2 leads to incremental increases (up to 18%) in nutrient application rates, yields and revenues. Both treatments improve low levels of nutrient use efficiency and reduce high levels of greenhouse gas emission intensity, after two years of treatment. Our findings underscore the possibility of a more gradual and sustainable intensification of smallholder agriculture in SSA, as compared with the Asian Green Revolution, through increased fertilizer use accompanied by improved fertilizer management.

Changes in maize traits and yield under the cultivar, environment and management interactions across China’s Maize Belt in the past two decades

It is important to investigate the response and adaptation mechanisms of crop traits and yield to ongoing climate change under genotype (G), environment (E), and management (M) interactions in order to develop climate-resilient cultivars and agricultural systems. Here, using long-term trial data at six comprehensive agricultural experiment stations across China’s Maize Belt, we investigated the changes in maize traits and yield during 1998–2019 under the interactions of G×E × M. The first-order difference, multi-collinearity detection, Pearson correlation, stepwise linear and a machine learning method were employed to construct the best statistical regression models between maize traits and climate variables and disentangle the relative contributions of climate, cultivar and management to grain yield changes. The results showed a warming trend but a decreasing trend in solar radiation at all the investigated stations. Climate variations affected maize traits and subsequently grain yield, and there were trade-offs among maize traits. With local agricultural management practices, about 20.5–73.8%, 1.2–42.7% and 2.3–37.0% of the yield changes were associated with climate change, cultivar shifts and management, respectively. The stations with higher latitudes exhibited greater variations in yield due to climate variations, compared to the stations with lower latitudes. Wind speed, radiation, and rainfall was found to affect maize yield in Northeast China by affecting evapotranspiration, soil moisture and drought occurrence. The ideal cultivars were characterized by a relatively long grain-filling stage, large hundred-grain weight and number of rows. This study gains new insights into the response and adaptation mechanisms of maize traits and yield to ongoing climate change, providing evidence for designing cultivar ideotypes and optimizing agricultural management in different environments.

Long‐term soybean–maize rotation experiments in cereal‐based farming systems at Bako, Western Ethiopia

AbstractMaize monoculture is one of the major restrictions limiting maize productivity in Western Ethiopia. Although the inclusion of legumes in cropping systems is an essential approach for the sustainable management of farming systems and for reducing the nitrogen (N) fertilizer requirement for maize production in the long term, the effects of soybean on the sustainability of maize productivity and soil fertility are unclear in Ethiopia. Continuous cropping of maize has led to extensive degradation of soil and a decrease in crop productivity in Western Ethiopia. Thus, the study was conducted to compare the long‐term impact of soybean on the sustainability of the production system in soybean–maize rotation and to monitor soil fertility dynamics in soybean–maize rotational systems. Nine different soybean–maize rotation treatments were laid out in Randomized Complete Block Design (RCBD) with three replications. The study results showed that soybean–maize rotation gave a relatively steady yield compared to the maize mono‐cropping system. Soybean–maize rotation improves the productivity of component crops in cropping systems. The highest maize grain yield was recorded from soybean–maize rotation with fertilizer application for the two components (RS + M+) and soybean–maize rotation without fertilizer application for the soybean component (RS‐M+), respectively. Soybean grain yield was significantly correlated with OC (%), OM (%), and TN (%), whereas maize yield was adversely correlated with soil parameters, except soil pH. Overall, the knowledge we can contribute to the readers from this study is that soybean–maize rotation plays an important role in achieving sustainable agriculture by increasing soil fertility and achieving stable soybean and maize yields and soybean should be inoculated with Rhizobium strain year after year continuously. Thus, it can be concluded that soybean–maize rotation with fertilizer applications (RS + M+) for two components can be used in maize belt areas of Western Ethiopia.

Short-term extreme heat at flowering amplifies the impacts of climate change on maize production

Extreme weather poses a threat to global crop production, food security and farmer livelihoods. High temperatures have been identified as detrimental to crop yields; however, how heat stress during the critical flowering stage will influence future maize (Zea mays L.) yields remains unclear. Here, we combined statistical and process-based models to assess impacts of short-term extreme heat at flowering on Chinese maize yield under climate change. We showed that heat around flowering has a stronger impact on yields than heat at other times in the growing season, especially for temperatures >30 °C. Heat stress during flowering was responsible for 23% of total yield loss from extreme degree days (EDDs) in 1990–2012. An improved process-based model (Agricultural Production Systems sIMulator (APSIM)-maize) incorporating a grain-temperature function was then applied and indicated that extreme heat at flowering amplified the impacts of climate change on maize production compared to the original model. The improved APSIM-maize predicted an 8.7% yield reduction across the Chinese Maize Belt as EDDs increased more than quadrupled at the end of the century (2070–2099) under a high emissions pathway (SSP585) in comparison with the baseline period (1990–2019). Our study highlights the importance of extreme heat at flowering on maize yield and can inform farmers and policy makers on adaptive measures as well as providing a reference for other crop areas facing similar challenges.

Evapotranspiration Partitioning Using a Process-Based Model over a Rainfed Maize Farmland in Northeast China

The Northeast China maize belt is one of the three major golden maize belts in the world and has been severely affected by climate change, however, the evapotranspiration (ET) partitioning is not clear. It is important to study ET and its components under climate change. In this paper, the water balance model SOILWAT2 was used to estimate ET partitioning in drought and humid years, seasons, and maize growth stages from 1989 to 2018 over rainfed maize farmland. The results indicated that the SOILWAT2 model performed well for the prediction of ET and its partitioning compared with eddy covariance measurements. The mean yearly ET, transpiration (T), soil evaporation (Es), and canopy interception evaporation (Int) were 432.3 mm, 197.6 mm, 204.7 mm and 19.2 mm, respectively, over 30 years. Es/ET was 6.3% lower in drought years than in humid years, T/ET was conversely higher (6.2% higher in drought years). There was no clear difference of Int/ET between humid and drought years. In the growing season, T/ET, Es/ET, and Int/ET varied from 40.0% to 75.0%, 22.8% to 55.7%, and 0.7% to 7.0%, respectively. T/ET decreased along with the growth of maize and was greatest at the greening–jointing stage. Es/ET was smallest at the greening–jointing stage. We found a power function relationship between T/ET, Es/ET, and leaf area index (LAI) and above-ground biomass. Our results indicated that for the rainfed farmland, drought may limit maize yield by increasing water loss of maize through increasing T under climate change conditions. Therefore, securing food yield will depend on increases in water-use efficiency and other adaptive strategies, such as drought-resistant varieties, and irrigation.

Optimizing Maize Belt Width Enhances Productivity in Wheat/Maize Intercropping Systems

Wheat/maize intercropping has been widely practiced in northwestern China. It is crucial to optimize the canopy structure and geometric configurations to enhance the performance of the system. This research determined the responses of intercrops to the different canopy structures created by the different wheat/maize intercropping systems. Field experiments were carried out in 2012, 2013, and 2014 at Wuwei, Gansu. Three intercropping patterns—six rows of wheat alternated with two rows of maize (6W2M), six rows of wheat alternated with three rows of maize (6W3M), and six rows of wheat alternated with four rows of maize (6W4M)—were compared with sole wheat and sole maize. The results showed that maize plant heights differed between the inner rows and the border rows, and the difference was greater for the 6W3M system than for the 6W4M system. The three intercropping systems had an average land-use equivalent ratio (LER, calculated based on grain yield) of 1.25, indicating an increase in land-use efficiency by 25% compared to the corresponding sole crops. The shape of maize strips in 6W3M optimized the canopy structure and increased the productivity of wheat and maize. The wheat in 6W3M had significantly more grain yield compared with the sole wheat and the 6W2M due to the maize belt shape, which resulted in the soil evaporation negatively affecting the intercropped wheat grain yield of the 6W3M. Similarly, the maize belt shape facilitated the light penetration and enhanced the reproductive growth by increasing the two cobs per plant rate (TCR) of the maize. The highest TCR of the 6W3M produced a higher maize grain yield than the 6W2M and sole maize in the three growing seasons. The maize belt width in the strip intercropping system had a significant effect on the grain yield of both wheat and maize, which reduced water evaporation, harmonized light distribution, and increased productivity.

Bt maize can provide non-chemical pest control and enhance food safety in China.

China is the world's second-largest maize producer and consumer. In recent years, the invasive fall armyworm Spodoptera frugiperda (J.E. Smith) has adversely affected maize productivity and compromised food security. To mitigate pest-inflicted food shortages, China's Government issued biosafety certificates for two genetically modified (GM) Bt maize hybrids, Bt-Cry1Ab DBN9936 and Bt-Cry1Ab/Cry2Aj Ruifeng 125, in 2019. Here, we quantitatively assess the impact of both Bt maize hybrids on pest feeding damage, crop yield and food safety throughout China's maize belt. Without a need to resort to synthetic insecticides, Bt maize could mitigate lepidopteran pest pressure by 61.9-97.3%, avoid yield loss by 16.4-21.3% (range -11.9-99.2%) and lower mycotoxin contamination by 85.5-95.5% as compared to the prevailing non-Bt hybrids. Yield loss avoidance varied considerably between experimental sites and years, as mediated by on-site infestation pressure and pest identity. For either seed mixtures or block refuge arrangements, pest pressure was kept below established thresholds at 90% Bt maize coverage in Yunnan (where S. frugiperda was the dominant species) and 70% Bt maize coverage in other sites dominated by Helicoverpa armigera (Hübner) and Ostrinia furnacalis (Guenée). Drawing on experiences from other crop/pest systems, Bt maize in se can provide area-wide pest management and thus, contribute to a progressive phase-down of chemical pesticide use. Hence, when consciously paired with agroecological and biodiversity-based measures, GM insecticidal crops can ensure food and nutrition security, contribute to the sustainable intensification of China's agriculture and reduce food systems' environmental footprint.

Influencing Factors of Soil Microbial Communities in Different Ecological Zones in the Golden Maize Belt in China: Environmental and Biochemical Factors

Influencing Factors of Soil Microbial Communities in Different Ecological Zones in the Golden Maize Belt in China: Environmental and Biochemical Factors

Improved mapping of nitrogen loss and surplus in China's maize belt

AbstractComprehensive, spatially explicit understanding of N loss from N input in China's maize (Zea mays L.) belt is needed to improve N management and develop N loss mitigation measures for specific locations. However, accurate estimation of N loss remains uncertain mainly because of spatial heterogeneity of emission factors (EFs) and activity data. Here, we built random‐forest models to predict EFs for each N loss pathway (dinitrogen, nitric oxide, nitrous oxide and ammonia emissions, nitrate leaching, and N runoff) considering soil and climate factors. We then used location‐ and crop‐specific activity data to understand N loss and surplus on a 1‐ × 1‐km grid. Results showed that the N surplus and total N loss averaged 135.4 (95% confidence interval [CI], 36.6–261.5) and 87.6 (95% CI, 32.9–162.5) kg N ha–1, respectively, and nitrate leaching and ammonia emissions were primary loss pathways. There was a significant correlation between N surplus and total N loss in spatial distribution, and regions with high N surplus and total N loss were mainly in the northern China Plain and Sichuan Basin, while regions with low surplus and loss could be found in Heilongjiang and Jilin provinces. Our results are beneficial to understand specific crop N budget and develop location‐specific N management strategies.

Soil properties resulting in superior maize yields upon climate warming

The impacts of global climate warming on maize yield vary regionally. However, less is known about how soil modulates regionally specific impacts and soil properties that are able to alleviate adverse impacts of climate warming on maize productivity. In this study, we investigated the impacts of multiple soil inherent properties on the sensitivity of maize yield (SY,T) to growing season temperature across China. Our results show that a 1°C warming resulted in the largest yield decline (11.2 ± 6.1%) in the mid-eastern region, but the moderate yield increase (1.5 ± 2.9%) in the north-eastern region. Spatial variability in soil properties explained around 72% of the variation in SY,T. Soil organic carbon (SOC) content positively contributed the greatest extent (28.9%) to spatial variation of SY,T, followed by field capacity (9.7%). Beneficial impacts of increasing SOC content were pronounced in the north-eastern region where SOC content (11.9 ± 4.3 g kg−1) was much higher than other regions. Other soil properties (e.g., plant wilting point, sand content, bulk density, and saturated water content) were generally negatively correlated with SY,T. This study is the first one to answer how soil inherent properties can modulate the negative impacts of climate warming on maize yield in China. Our findings highlight the importance of SOC in alleviating adverse global warming impacts on maize productivity. To ensure food security for a rapidly increasing population under a changing climate, appropriate farming management practices that improve SOC content could reduce risk of adverse effects of global climate warming through a gain in yield stability and more resilient production in China’s maize belt.

Evaluation of Drought Vulnerability of Maize and Influencing Factors in Songliao Plain Based on the SE-DEA-Tobit Model

Rain-fed agriculture is easily affected by meteorological disasters, especially drought. As an important factor of risk formation, actively carrying out agricultural drought vulnerability assessments is conducive to improving food security and reducing economic losses. In this study, an SE-DEA model with regional exposure and drought risk as input factors and the maize yield reduction rate and drought-affected area as output factors is established. The aim is to evaluate and zone the drought vulnerability of the maize belt in the Songliao Plain. The results show the following: (1) From 2000 to 2019, the drought vulnerability of maize showed a fluctuating increasing trend. The vulnerability in Harbin and central Jilin Province is high, which is extremely unfavorable for maize production. (2) Comparing the historical disaster data with the drought vulnerability map generated using the SE-DEA model, it could be found that the results obtained using the SE-DEA model are reliable. (3) The Tobit model shows that the proportion of the effective irrigated area is more important to alleviate vulnerability. For drought vulnerability zoning using a cluster analysis, we suggest that regulated deficit irrigation should be actively developed in high-vulnerability areas to ensure maize yield while improving water efficiency. The results of this study can provide a basis for the development of drought mitigation and loss reduction strategies, and they provide new ideas for future research.

Maize nutrient yield response and requirement in the maize belt of Nigeria

Absence of site-specific nutrient recommendation and high spatial variability of soil fertility are major factors affecting maize response to applied nutrients in Nigeria. In this study, we assessed maize response to applied nutrients and nutrient use efficiency in different management zones (MZs), for designing site-specific nutrient management recommendations for maize in the maize belt of Nigeria. The maize belt in Nigeria was earlier delineated into four MZsMZs (MZ1 to MZ4) based on soil properties. In the current study, data from two different trials, nutrient omission trials (N = 293) and fertilizer response trial (N = 705), conducted in the years 2015–2017, were extracted for MZ1 to MZ3; to analyze maize yield responses to application of N, P and K, and secondary and micro-nutrients. Maize yield response to K application was only positive in MZ1. Responses to N and P application were positive for all MZs. However, the magnitude of maize response to P varied between the MZs, indicating a differentiation in the degree to which P is limiting maize production in the study area. Average nitrogen requirement was higher for MZ3 (138 kg ha−1), than for MZ2 and MZ1 (121 and 83 kg ha−1, respectively). Average P requirement was higher for MZ3 (45 kg ha−1) than for the other zones. Potassium requirement was 26% and 28% higher in MZ2 and MZ3 compared with MZ1 (∼15 kg ha−1). The use of the specific nutrient rates for the MZs may reduce risks and uncertainties in crop production. The delineated MZs of the maize belt of Nigeria that incorporates spatial variability in soil fertility conditions are useful for nutrient management for larger areas.

Long-term effects of crop rotation and nitrogen fertilization on phosphorus cycling and balances in loess-derived Mollisols

Developing meaningful agroecosystem soil P inventories necessitates moving beyond single measures of readily extractable inorganic P (Pi) limited to surface depths. We drew on a long-term (36 year) experimental field trial in the US Maize Belt (northwestern Illinois) to evaluate how crop rotation [maize-maize (Zea mays L.) vs maize-soybean (Glycine max L. Merr.)] and N fertilization (0 vs 269 kg N ha−1) impact P dynamics throughout the soil profile by using sequential fractionation and phosphatase activity assays, contextualized by soil P stocks and agronomic P balances. Distribution of P fractions by depth (0–15, 15–30, 30–60, 60–90 cm) indicate that management effects were limited to the surface soil layers (0–30 cm). Soil P fractions differed more by depth than by experimental treatments. Long-term N fertilization significantly decreased pH concurrently with labile organic P (Po) and phosphodiesterase activity. Soil labile inorganic P (Pi) was two-fold lower under N fertilization compared to zero N fertilization, reflecting greater yield and thus P export via grain harvest. Under N fertilization, integration of soybean elevated soil phosphodiesterase activity and decreased water-extractable Po. Higher stocks of soil Po than labile Pi at surface depths (0–30 cm) corroborated a hypothesized appreciable pool size of soil Po relative to the labile Pi pool to which most agronomic assessments are limited. Large negative agronomic balances over the 36-year period (−426 to −945 kg P ha−1) are suggestive of legacy P from pre-experiment manure application and high native P stocks, with net P export equivalent to 11–35% of soil P stocks at 0–90 cm depth at the initiation of the experiment. These results contribute to a better understanding how N fertilization and rotation practices influence soil P cycling and stocks, thereby informing P budgets for comprehensive agroecosystem P management.

Dominant sources of uncertainty in simulating maize adaptation under future climate scenarios in China

CONTEXTThe potential of climate adaptation has been widely investigated with a climate-crop modeling approach. Although different sources of uncertainty in projected crop yields have been quantified in climate change impact assessments, uncertainty in simulating the crop adaptation to future climate has not been fully assessed. OBJECTIVEThe objective of this study was to determine the uncertainty in simulating maize adaptation to future climate change with two adaptation options (adjusting planting date and shifting cultivars) at four contrasting sites across China's Maize Belt. METHODSMaize yield with adaptation was simulated using three crop models (APSIM, DSSAT-CERES, and STICS) driven by 22 global climate models (GCMs) under four emission scenarios of future societal development pathway (SSP126, SSP245, SSP370, and SSP585) during two periods (2040–2069 and 2070–2099). RESULTS AND CONCLUSIONSWe found that late planting had a greater potential to cope with climate change at most study sites. However, all sites required new cultivars with increased thermal time requirements. Under optimum management options at the four study sites, rainfed maize yields were likely to increase by 1.9%–68.3% compared with yields obtained without adaptation. For the adaptation simulation using adjusted planting date alone, GCM was the major source of uncertainty, accounting for 22.9%–36.7% of the total uncertainty at all sites except a high-altitude site where changing planting time was the major source of uncertainty (32.4%). For the adaptation simulation using shifting cultivar alone, crop model was the dominant source of uncertainty, accounting for 24.0%–38.0% of the total uncertainty at all sites except a high-latitude site where shifting cultivar was the major source of uncertainty (34.0%). These findings demonstrated that adaptation options have great potential for increasing maize yields, and the major source of uncertainty depends on study sites and adaptation type used. SIGNIFICANCEThe results of this study advance the understanding of the dominant sources of uncertainty in crop yield under different climate adaptations, thereby improving our confidence in assessments of future climate impact on maize yields determined by different adaptation strategies.

Yield-limiting plant nutrients for maize production in northwest Ethiopia

Summary The potential yield of improved maize varieties usually cannot be fully realised mainly due to inappropriate soil nutrient management practices in most parts of Ethiopia. Site-specific fertiliser recommendations are rarely used in the farming systems of Ethiopia. There is also a lack of data to develop or validate decision support tools for targeting specific crop production. A study was conducted for three consecutive rainy seasons (2016–2018) in the maize belt of the north-western parts of the Amhara National Regional State of Ethiopia. The objectives were to obtain the maximum achievable yield potential of maize, determine the most yield-limiting nutrients and create a database of maize responses to applied nutrients so that decision support tools could be developed for the study areas. Treatments were individual nutrients (nitrogen (N), phosphorus (P) and potassium (K)) and combinations of the three. In some treatments, NPK was also combined with sulphur, zinc, lime and compost. Two hybrid maize varieties (BH-540 and BH-660) adaptable to the study areas were used. BH-540 was used for the Mecha district, while BH-660 was used for the south Achefer, Jabitahnan–Burrie–Womberma districts. Maize yield increased by more than 50% due to fertiliser applications compared to without fertiliser. The study showed that the possibility of increasing maize productivity to more than 12 t ha-1 for the study sites. The most yield-limiting nutrient in the study sites was N, followed by P; K was not a yield limiting. Without N the yield of both varieties was non-significant from the control (without added nutrients). Maize grain yield did not respond to application of lime, compost, zinc and sulphur. The result also showed very high variability across sites, indicating that it is important for policymakers, farmers and investors to consider site-specific fertiliser recommendations. Finally, a database containing intensive plant response to NPK for maize was generated and could be used as input in site-specific decision support tools development.

Assessing maize potential to mitigate the adverse effects of future rising temperature and heat stress in China

Rising temperatures and frequent extreme high temperature events under future climate scenarios have posed pressing challenges with respect to global food security. Previous climate-crop modelling studies have investigated the impacts of rising temperature and heat stress on grain yield. However, the potential and priority of dealing with rising mean temperature or heat stress using genetically different cultivars have not been identified. We investigated the impacts of climate change on maize yield across China's Maize Belt (23°–48°N) using the CERES-Maize model driven by future climate scenarios under contrasting maize growing season temperatures of 18–24°C during the 2050s (2040–2069) and the 2080s (2070–2099). We also assessed the potential of different cultivars to adapt to rising temperatures and heat stress with an extreme hot global climate model from CMIP6 under a high emission scenario (SSP585). Our simulated results indicated that the shortened growth period resulting from rising temperatures, decreased photosynthesis caused by heat stress, and decreased grain-filling rate due to heat stress were the main reasons causing future maize (Zea mays L.) yield decreases in all subregions of China's Maize Belt. The priority applied to using a cultivar with a longer growth period or higher heat-tolerance to cope with climate warming depends on the particulars of the local climate and cropping system. Specifically, the potential for adapting to rising temperature is generally higher than the potential for adapting to heat stress in all subregions except the North China Plain (NCP) where the potential for adapting to heat stress is higher than the potential for adapting to rising temperature. Our study demonstrated the necessity of using cultivars with appropriate traits to alleviate the adverse effects of climate warming. Also, our findings provide important information for the direction and priority of future breeding in different climate regions with various cropping systems across China's Maize Belt.