InfoCrop: A dynamic simulation model for the assessment of crop yields, losses due to pests, and environmental impact of agro-ecosystems in tropical environments. I. Model description

ABSTRACTAnthropogenic nitrogen (N) deposition significantly alters soil aggregate (SA) stability and soil organic carbon (SOC) dynamics in grassland ecosystems, though the effects of varying N deposition levels remain inadequately understood. Here we evaluate the effect of varying N addition levels on SA and organic carbon stability. A 6‐year N addition experiment was conducted in a desert steppe, comprising CK (0 g·m−2·yr.−1), low N (5 and 10 g·m−2·yr.−1), medium N (20 g·m−2·yr.−1), and high N (40 g·m−2·yr.−1) treatments. This research examined SA stability, GRSP, SOC dynamics, and carbon flow pathways using Fourier transform infrared and 13C stable isotope analysis. Medium N addition enhanced macro‐SA content (> 0.25 mm) by 20.5% and improved SA stability through increased SOC accumulation, while high N addition decreased macro‐SA content by 7.47%. SOC concentrations in micro‐SA (0.25–0.053 mm) and silt + clay (SC) (< 0.053 mm) increased substantially under low and medium N inputs. Polysaccharide‐C levels were elevated in macro‐SA, whereas phenolics‐C and aliphatic‐C predominated in micro‐SA. Low N addition increased aliphatic‐C in SA, while medium and high N levels reduced it. N addition elevated phenolics‐C and aromatic‐C, particularly in macro‐SA. Both easy extractable GRSP (EE‐GRSP) (r = 0.71*) and T‐GRSP (r = 0.59*) correlated positively with SOC, emphasizing GRSP's importance in SOC accumulation. N addition enhanced carbon flow among SA through microbial decomposition and anabolic processes, with plant‐derived carbon preferentially accumulating in macro‐SA and SC. Medium N input optimally promotes SA stability and SOC in desert steppes, providing important insights for understanding N deposition's role in climate change mitigation.

<p>Soil erosion in croplands has a strong impact on global carbon (C) cycle. Assessment of erosional effects on soil organic carbon (SOC) dynamics in agricultural soils suffers from the difficulty of distinguishing the erosional effects and complex interaction processes between erosion and C cycling. To simulate the effects of soil erosion, a plots experiment including six erosion levels (0, 5, 10, 20, 30, and 40 cm eroded) was conducted for seven years (2012-2018). The erosion levels were simulated using artificial soil profiles created by mixing soils from different layers in the original soil profile (never eroded) in a certain proportion. Subsequently, based on the field observations during 2012-2018, the SOC dynamics of each experimental plot were simulated by using a process-oriented C cycle model (denitrification-decomposition (DNDC)) to quantify the effects of erosion on SOC dynamics. The measurements at the beginning of the plots experiment showed that simulated erosion resulted in the depletion of SOC with an average reduction rate of 9.7% per 10 cm of soil loss; SOC in eroded soils recovered after seven years of cropping, the declining slope of the SOC measured in 2018 was 3.0% per 10 cm of soil loss, suggesting that dynamic replacement had occurred. Model simulation results indicated that soil erosion could reduce the C inputs from crop residue by lowering soil productivity; soil heterotrophic respiration in eroded soils was restricted due to the lower initial SOC content. As a result, the simulated overall SOC stock in eroded soils was restored after erosion stopped because of the lower C output. These results indicated that SOC loss at eroding sites was caused mainly by lateral transport rather than enhanced decomposition. The fate of the displaced SOC within catchments is key to assess the net impacts of soil erosion on SOC dynamics at a large scale.</p>

Simulating the effects of erosion on organic carbon dynamics in agricultural soils

Soil organic carbon dynamics along chrono-sequence land-use systems in the highlands of Ethiopia

Assessing the vulnerability of Indian mustard to climate change

Earthworms increase soil greenhouse gas emissions reduction potential in a long-term no-till Mollisol

State‐of‐the‐art predictive models of soil organic carbon (SOC) dynamics associated with land use changes are unable to reflect the diversity of tropical soil types as the knowledge of contrasting site‐specific factors in mediating the response of the SOC pool is sparse. This paper examines the influence of soil type and management on SOC dynamics following the conversion of forests to annual cropping in Ghana. Soil from primary forests and from areas with short (2–7 years) and long (20 years) histories of maize cultivation was sampled from a Vertisol dominated by smectite and Ultisol dominated by kaolinite. Wet sieving was used to separate soil fractions below and above 250 µm. SOC concentrations and δ13C signatures of SOC in soil fractions and bulk soil were determined. SOC stocks were calculated by the commonly used fixed depth approach and by the equivalent soil mass approach. After 20 years of cultivation of the Vertisol, the total SOC content was 40 per cent lower than under forest, and about 95 per cent of the forest‐derived SOC had been lost. After 20 years of cultivation of the Ultisol, total SOC content was only about 20 per cent lower than under forest and merely 30 per cent of the forest‐derived SOC had been lost. Both soil types were managed as they would typically be in small scale farming systems, thus the higher SOC losses and the substantial loss of forest‐derived SOC from the Vertisol question the conventional concept of smectite having a higher SOC‐stabilizing potential than kaolinite under field conditions. Copyright © 2013 John Wiley & Sons, Ltd.

Greenhouse gas emissions and stocks of soil carbon and nitrogen from a 20-year fertilised wheat-maize intercropping system: A model approach

Climate change may significantly impact crop yields and soil. In this study the DNDC model, together with climatic outputs from Hadley Centre’s general circulation model (HadCM3), was used to investigate the influence of projected climate change and management practices on soil organic carbon (SOC) dynamics and crop yield of the Chinese Loess Plateau. The results identify management practices with the greatest potential to mitigate climate change and to increase SOC in this area. Field experiments on winter-wheat (Triticum aestivum L.) and summer maize (Zea mays L.) rotation included a control and four types of fertilization treatments: T1 (control), T2 (inorganic fertilizer), T3 (NPK inorganic fertilization combined with wheat or maize residue return), T4 (NPK inorganic fertilization combined with low amount of manure) and T5 (NPK inorganic fertilization combined with high amount of manure). DNDC model was calibrated using the field data from 1991 to 2000 and validated from 2001 to 2010. Furthermore, a baseline climate and three future climate scenarios (A1B, A2 and B1) were considered. DNDC model effectively simulated the SOC and crop yields. The findings showed that in 1991–2010, T1 maintained its initial SOC level but reduced crop yields, while T2 promoted crop production with less effect on soil carbon storage. However, T3, T4 and T5 enhanced both crop yield and soil carbon, and the best results were observed under T5. The investigated climate scenarios substantially affect SOC content and crop yields. In terms of SOC content, B1 had great effects on T1, T4 and T5, while A1B on T2 and T3. Considering crop yields, in all treatments, the trends are B1 > A1B > A2 for winter-wheat and A2 > A1B > B1 for summer maize, respectively. The impacts of climate changes on SOC dynamics and crop yields were different depending on the management applied. Thus, the adoption of certain management practices in the Chinese Loess Plateau agroecosystems could be critical in maximizing SOC sequestration and reducing CO2 in the atmosphere. Reasonably low temperature and high precipitation can enhance winter-wheat yields, while maize yields need medium temperature and precipitation. We recommended the combined application of inorganic and organic fertilizers to achieve a balance between food security and soil carbon sequestration objectives.

Simulating greenhouse gas emissions and stocks of carbon and nitrogen in soil from a long-term no-till system in the North China Plain

Simple SummaryThe livestock sector requires a significant amount of natural resources and has an important role in climate change. Although the carbon footprint has become a widely accepted indicator for assessing the greenhouse gases emitted per unit of product, due to the lack of a commonly accepted methodology, there are still few studies that have included soil organic carbon sequestration in their calculations. In this study, by including soil organic carbon dynamics, the carbon footprint of a Mediterranean pasture-based beef cattle farm was estimated using current weather data and farming management policies. Subsequently, different soil management strategies, grazing systems, and climate scenarios were compared to the current ones to investigate the effects of these variables on the greenhouse gases emitted. The results showed that the current beef carbon footprint could be significantly reduced by switching to reduced tillage systems. The modeled combination of no-tillage practices with higher organic fertilizer application rates showed a greater potential carbon footprint reduction. No significant differences were found between carbon footprint values modeled under different climate scenarios and grazing systems. By including a process-based model into its carbon footprint calculations, this study highlights the climate mitigation potential of different farming practices and the importance of considering soil carbon sequestration. A better understanding of soil organic carbon (SOC) dynamics is needed when assessing the carbon footprint (CFP) of livestock products and the effectiveness of possible agriculture mitigation strategies. This study aimed (i) to perform a cradle-to-gate CFP of pasture-based beef cattle in a Mediterranean agropastoral system (ii) and to assess the effects on the CFP of alternative tillage, fertilizing, and grazing practices under current (NCC) and future climate change (CC) scenarios. Minimum (Mt) and no-tillage (Nt) practices were compared to current tillage (Ct); a 50% increase (Hf) and decrease (Lf) in fertilization was evaluated against the current (Cf) rate; and rotational grazing (Rg) was evaluated versus the current continuous grazing (Cg) system. The denitrification–decomposition (DNDC) model was run using NCC as well as representative concentration pathways to investigate the effects of farm management practices coupled with future CC scenarios on SOC dynamics, N2O fluxes, and crop yield. Within NCC and CtCf, an emission intensity of 26.9 ± 0.7 kg CO2eq per kg live body weight was estimated. Compared to Ct, the adoption of Mt and Nt reduced the CFP by 20% and 35%, respectively, while NtHf reduced it by 40%. Conservation tillage practices were thus shown to be effective in mitigating greenhouse gas emissions.

Vegetation controls on soil organic carbon dynamics in an arid, hyperthermic ecosystem

InfoCrop: A dynamic simulation model for the assessment of crop yields, losses due to pests, and environmental impact of agro-ecosystems in tropical environments. II. Performance of the model

Simulating synergistic effects of climate change and conservation practices on greenhouse gas emissions and crop growth in long-term maize cropping systems

SUMMARYIn recent years, simulation models have been used as a complementary tool for research and for quantifying soil carbon sequestration under widely varying conditions. This has improved the understanding and prediction of soil organic carbon (SOC) dynamics and crop yield responses to soil and climate conditions and crop management scenarios. The goal of the present study was to estimate the changes in SOC for different cropping systems in West Africa using a simulation model. A crop rotation experiment conducted in Farakô-Ba, Burkina Faso was used to evaluate the performance of the cropping system model (CSM) of the Decision Support System for Agrotechnology Transfer (DSSAT) for simulating yield of different crops. Eight crop rotations that included cotton, sorghum, peanut, maize and fallow, and three different management scenarios, one without N (control), one with chemical fertilizer (N) and one with manure applications, were studied. The CSM was able to simulate the yield trends of various crops, with inconsistencies for a few years. The simulated SOC increased slightly across the years for the sorghum–fallow rotation with manure application. However, SOC decreased for all other rotations except for the continuous fallow (native grassland), in which the SOC remained stable. The model simulated SOC for the continuous fallow system with a high degree of accuracy normalized root mean square error (RMSE)=0·001, while for the other crop rotations the simulated SOC values were generally within the standard deviation (s.d.) range of the observed data. The crop rotations that included a supplemental N-fertilizer or manure application showed an increase in the average simulated aboveground biomass for all crops. The incorporation of this biomass into the soil after harvest reduced the loss of SOC. In the present study, the observed SOC data were used for characterization of production systems with different SOC dynamics. Following careful evaluation of the CSM with observed soil organic matter (SOM) data similar to the study presented here, there are many opportunities for the application of the CSM for carbon sequestration and resource management in Sub-Saharan Africa.