• Energy Research

SummaryThe North Wyke Farm Platform (NWFP) provides data from the field‐ to the farm‐scale, enabling the research community to address key issues in sustainable agriculture better and to test models that are capable of simulating soil, plant and animal processes involved in the systems. The tested models can then be used to simulate how agro‐ecosystems will respond to changes in the environment and management. In this study, we used baseline datasets generated from the NWFP to validate the Soil‐Plant‐Atmosphere Continuum System (SPACSYS) model in relation to the dynamics of soil water content, water loss from runoff and forage biomass removal. The validated model, together with future climate scenarios for the 2020s, 2050s and 2080s (from the International Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES): medium (A1B) and large (A1F1) emission scenarios), were used to simulate the long‐term responses of the system with three contrasting treatments on the NWFP. Simulation results demonstrated that the SPACSYS model could estimate reliably the dynamics of soil water content, water loss from runoff and drainage, and cut biomass for a permanent sward. The treatments responded in different ways under the climate change scenarios. More carbon (C) is fixed and respired by the swards treated with an increased use of legumes, whereas less C was lost through soil respiration with the planned reseeding. The deep‐rooting grass in the reseeding treatment reduced N losses through leaching, runoff and gaseous emissions, and water loss from runoff compared with the other two treatments.

Context: Climate change is projected to threaten food security and stimulate greenhouse gas emissions. Hence, adaptation measures without sacrificing food production are required. Objective: To assess possible consequences of rice system under climate change and to propose possible practices for mitigation. Methods: The SPACSYS was tested using datasets from long-term experiment (since 1991) assessing the impact of different fertilisation on crop production, crop nitrogen (N) content, soil organic carbon (SOC) storage, methane (CH4) and nitrous oxide (N2O) emissions in a Cambisol under rice–wheat system. The validated SPACSYS was then used to investigate the possible mitigation strategies from 2024 to 2100 under climate change scenarios (SSP1–2.6 and SSP5–8.5) and the baseline scenario and management scenarios, i.e., (i) reduced N application rate by 20 % (RNA), (ii) the introduction of mid-season drainage (MSD) and (iii) integrated management (IM). Results and conclusions: Results showed that SPACSYS performed effectively in simulating yield and N content in grain and straw, SOC storage and CH4 and N2O emissions, with R2 ranging from 0.21 to 0.67, modelling efficiency from 0.12 to 0.63 and index of agreement > 0.59. Scenarios analysis elucidated that RNA would not decrease grain yields for either rice or wheat under the two climate change scenarios. Compared to the baseline scenario, low level of climate change scenario considering the CO2 fertilisation effects (SSP1–2.6_CO2) may benefit wheat yield (28 %) and had no effects on rice yield. In contrast, under the SSP5–8.5 scenario, whether CO2 fertilisation effects are considered or not, both rice and wheat yield could face great loss (i.e., 11.8–29.9 % for rice, 8.3–19.4 % for wheat). The winter wheat would not be suitable for planting in the distant future (2070–2100) due to the incomplete vernalisation caused by warming. The switching from winter wheat to spring wheat from 2070 onward could avoid the yield loss by 8.3–19.4 %. Climate change could decrease SOC sequestration rate. Under the SSP1–2.6 and SSP5–8.5 scenarios, IM could reduce CH4 emissions by 55 % and 57 % and N2O emissions by 23 %, as such reducing the net global warming potential by 59 % compared to no adaptation. Our simulations suggest that under climate change, crop switching in rice–wheat system combining integrated mitigation practices is possible to mitigate global warming and maintain crop production. Significance: Our results underscore the significance of integrated adaptation of agricultural systems to climate change.

Chemical fertiliser nitrogen addition will inhibit biological nitrogen fixation (BNF) for soybean (Glycine max [L.] Merr) growth. The optimal balance of these two nitrogen input sources has been a key issue for sustainable development in Northeast China. We used the data collected from a four-year experiment with varied irrigation and fertiliser treatments from 2007 to 2010 to evaluate the SPACSYS (Soil-Plant-Atmosphere Continuum SYStem) model. The validated model was run to investigate the responses to different management practices in seed yield, BNF, protein yield and soil nitrogen budgets. Scenario testing showed average yield increase of 2.4–5.2% with additional 50–100 kg N/ha application. Irrigation at the reproductive stage improved seed yield in drier years with an increase of 12–33% compared with the rain-fed treatment. BNF was suppressed by fertiliser nitrogen application and drought stress with a decrease of 6–33% and 8–34%, respectively. The average nitrogen budget without fertilization indicated a deficit of 39 kg N/ha. To attain higher seed yield, applying fertiliser at 25–30 and 15–20 kg N/ha before sowing is advised in drier and wetter years, respectively. To achieve a higher seed nitrogen content, an application rate of 55–60 and 45–50 kg N/ha is recommended for drier and wetter years, respectively.

Southwestern China (SWC), one of the major rain-fed wheat production zones in China, has become vulnerable to drought in recent years under global climate change. To quantify drought severity during the wheat growing season and its impact on yield loss, we selected the Agricultural Production Systems sIMulator (APSIM) model to simulate wheat growth between 1961 and 2010 in SWC. A new drought index was developed considering different weighting factors of drought for yield loss in three growing phases. The index was shown to be reliable in assessing drought severity in the region. On average, an abnormal drought mainly occurred in mid-west Guizhou with a frequency of 10–30%. Central SWC was subjected to moderate drought with a frequency of 10–30%, whereas severe drought often occurred in Southern Sichuan and the middle of Yunnan with a frequency >50%. Temporally, drought severity fluctuated before 1990, but increased significantly afterwards. Our assessment suggested that irrigation during the period from floral initiation to flowering would help to ameliorate the effects of water stress under climatic variability in the region.

In the face of global climate change, changes in nitrogen use efficiency (NUE) have not been widely considered to affect agricultural productivity. A modeling study was conducted to assess the impacts of future climates on crop yields and NUE in two wheat (Triticum aestivum L.) and maize (Zea mays L.) rotation systems and one continuous maize system in northern China. Specifically, the process-based SPACSYS model was used to predict crop yields and NUE by 2100, under four climate scenarios (Baseline, RCP2.6, RCP4.5 and RCP8.5). The model was validated using data from three long-term experiments, each of which included four fertilization practices typical of the regions: non-fertilizer, combined mineral N, phosphorus (P) and potassium (K) (NPK), NPK plus manure and NPK plus straw. Validation showed SPACSYS well-simulated crop yields and N uptake (R2: 0.41–0.96; RMSE: 6–18%; and EF: 0.41–0.93). Under future climate change, the model predicted changes in maize yield by − 30.69% and 5.98% in northwestern and northeastern China, respectively, and wheat yield by − 16.37% in northwestern China. Future climates would cause greater NUE reductions in the northwest (wheat: 42.79%; maize: 33.73%) than in the northeast (maize: 3.97%) with smaller decreases in crop N uptake and N loss. Furthermore, manure application had higher crop NUEs (wheat: 6.66–31.27%; maize: 23.82–68.19%) and N uptakes than other treatments under future climate change. The results demonstrated the risks of future climate changes on crop yield and NUE in the study regions and can also help target fertilization practices for effectively mitigating climate change.

<List> <ListItem><ItemContent><p>● Either increasing C input to or reducing C release from soils can enhance soil C sequestration.</p></ItemContent></ListItem> <ListItem><ItemContent><p>● Afforestation and reforestation have great potential in improving soil C sequestration.</p></ItemContent></ListItem> <ListItem><ItemContent><p>● Long-term observations about the impacts of biochar on soil C sequestration are necessary.</p></ItemContent></ListItem></List></p> <p>Climate change vigorously threats human livelihoods, places and biodiversity. To lock atmospheric CO2 up through biological, chemical and physical processes is one of the pathways to mitigate climate change. Agricultural soils have a significant carbon sink capacity. Soil carbon sequestration (SCS) can be accelerated through appropriate changes in land use and agricultural practices. There have been various meta-analyses performed by combining data sets to interpret the influences of some methods on SCS rates or stocks. The objectives of this study were: (1) to update SCS capacity with different land-based techniques based on the latest publications, and (2) to discuss complexity to assess the impacts of the techniques on soil carbon accumulation. This review shows that afforestation and reforestation are slow processes but have great potential for improving SCS. Among agricultural practices, adding organic matter is an efficient way to sequester carbon in soils. Any practice that helps plant increase C fixation can increase soil carbon stock by increasing residues, dead root material and root exudates. Among the improved livestock grazing management practices, reseeding grasses seems to have the highest SCS rate.

Context: Global food production is facing severe challenges due to climate change. Previous climate-crop modeling studies have developed multiple adaptation strategies, such as adjusting sowing dates, densities, and optimizing cultivars, to counteract the negative impacts of climate change. In northwest China, plastic mulching (PM) is extensively utilized to alleviate drought stress, improving both yield and water use efficiency (WUE). Nonetheless, the integration of PM with prevalent agricultural practices to formulate a comprehensive strategy for adapting to climate change has not been investigated. Objective: We aim to integrate different virtual cultivars, sowing dates, and plant densities with PM practices to identify the most effective strategies for enhancing yield and WUE under climate change. Methods: The simulation of maize yield and WUE under adaptive conditions was conducted using the SPACSYS (Soil-Plant-Atmosphere Continuum System) model. The model was calibrated and validated with five-year field observation data at Yangling in northwest China. It was driven by climate data projected from one Global Climate Model identified as representing the worst-case scenario from the Coupled Model Intercomparison Project phase 6 for the study site. The simulations were based on a high emission scenario of future societal development pathway (SSP585) during two periods (2021–2060 and 2061–2100). Results: Our simulation results show that future maize yield without adaptation was projected to decrease by 4.3 % in the 2040s (2021–2060) and 56.0 % in the 2080s (2061–2100). We found that postponing sowing dates by 15 days and increasing plant density to 7.5–9 plants m–2 can boost yield and WUE in future climate scenarios. Furthermore, when PM was integrated with optimal virtual cultivar under optimal planting date and density, the simulated yield rose by 97.6 % and 25.5 % in the 2040s and 2080s, respectively, relative to the reference management, while WUE rose by 162 % and 114 %, respectively. Conclusions: Integrating PM with delayed sowing and higher planting densities can enhance maize yield and WUE under future climates. An optimal climate-adapted maize cultivar should have longer growth durations, higher specific leaf area, and improved carbohydrate transfer rates than current cultivars. These results underscore the significant potential of combining optimal genotype and agronomic options to enhance yield and WUE under climate change in arid rainfed regions. Significance: This research offers valuable insights for breeders and agronomists in formulating genotype × management strategies to cope with climate change.

CONTEXT The Stipa breviflora desert steppe ecosystem is fragile and sensitive to climate change and grazing disturbance. Previous studies have reported the effects of climate change and grazing on aboveground standing biomass of the plant community and sheep live weight, however, the interaction between climate change and grazing remains unclear. Process models have become ideal tools for the evaluation of the effects of grazing management practices under climate change. OBJECTIVE We used the Soil-Plant-Atmosphere Continuum System (SPACSYS) model to investigate aboveground standing biomass and the live weight of sheep in the desert steppe of Inner Mongolia under future climate change scenarios and different grazing management. The results will be used to inform adaptive management strategies. METHODS The grazing experiment consisted of four treatments: no grazing (0 sheep ha−1 half year−1), light stocking rate (0.91 sheep ha−1 half year−1), moderate stocking rate (1.82 sheep ha−1 half year−1), and high stocking rate (2.71 sheep ha−1 half year−1). We used observed data on soil temperature, soil volumetric water content, changes to sheep live weight, and aboveground standing biomass of plant community to provide parameterization and validation for the SPACSYS model. We then predicted aboveground standing biomass of the plant community and sheep live weight changes for different grazing management under three representative concentration pathways (RCP) scenarios (RCP 2.6, RCP 4.5, and RCP 8.5) from 2021 to 2100. RESULTS AND CONCLUSIONS Moderate and high stocking rates decreased aboveground standing biomass and sheep live weight changes more than the light stocking rate. A light stocking rate can maintain higher aboveground standing biomass and sheep live weight as well as meet production requirements. Therefore, a light stocking rate is a potentially effective management approach to improve food production security and combat global climate change in the desert steppe. SIGNIFICANCE The model can inform management strategies for grazing in the desert steppe under climate change, supporting efforts to maintain the stability of the steppe ecosystem and increase economic benefits, while also providing a theoretical basis for adaptive management in the desert steppe