Evaluation of three different regional climate change scenarios for the application of a water balance model in a mesoscale catchment in Northeast Germany

Future climate changes might have some impacts on catchment hydrology. An assessment of such impacts on e.g. ground water recharge is required to derive adaptation strategies for future water resources management. The main objective of our study was an analysis of three different regional climate change scenarios for a catchment with an area of 2415 km² located in the Northeastern German lowlands. These data sets consist of the STAR-scenario with a time period 1951–2055, the WettReg-scenario covering the period 1961–2100 and the grid based REMO-scenario for the time span 1950–2100. All three data sets are based on the SRES scenario A1B of the IPCC. In our analysis, we compared the meteorological data for the control period obtained from the regional climate change scenarios with corresponding data measured at meteorological stations in the catchment. The results of this analysis indicated, that there are high differences between the different regional climate change scenarios regarding the temporal dynamics and the amount of precipitation. In addition, we applied a water balance model using input data obtained from the different climate change scenarios and analyzed the impact of these different input data on the model output groundwater recharge. The results of our study indicated, that these regional climate change scenarios due to the uncertainties in the projections of precipitation show only a limited suitability for hydrologic impact analysis used for the establishment of future concrete water management procedures in their present state

Model intercomparison for calibrated models

The study ROTATIONEFFECT aims to compare the output of different models simulating field data sets with multi-year crop rotations including different treatments.Within the first Step (1a2a) data sets (comprising a total of 301 crop growth seasons) for 5 locations in Europe were distributed to 15 interested modeller groups.For this step only minimal information for calibration were provided to the modellers. In total 15 modelling teams sent their “uncalibrated” results as single-year calculations and/or continuous calculations of rotation depending on the capability of the model. Results have been evaluated and the paper submitted (European Journal of Agronomy).Now, within the 2nd step (1b2b) modellers were provided with more information on the crop for the calibration of models. Again, results of calibrated runs were collected.6 models were capable to run the rotations as continuous runs and another set of 6 models provided single year simulations.A first overview of the improvement of predictions due to calibration has been produced. Result files have been uploaded to the web platform for CropM results at Aarhus University (Work package C2 – data management)

Simulating crop rotations and management across climatic zones in Europe – an intercomparison study using fifteen models

Process based crop simulation models are widely used to assess crop production under current or future climate conditions. Most studies on climate impacts on crop growth are so far focussed on single crops and single-year simulations. However, it is known that the position of crops within a rotation can influence crop growth significantly due to carry-over effects between seasons. We compared crop models on crop rotation effects from five sites across Central Europe providing in total data of 301 cropping seasons and treatments. Treatments comprised irrigation, nitrogen (N) fertilisation, atmospheric [CO2], tillage, residue management, cover crops and soils. Crop rotations were simulated with 15 crop models as single-year simulations and/or continuous simulations over whole crop rotations in “restricted calibration” runs. Lower RMSE between observed and simulated crop yields were obtained for continuous runs as compared to single-year runs. Relatively low carry-over effects were observed due to equilibration of soil water over winter and high N fertilisation levels. Consistently, a sub-set of models applied to an additional rainfed Mediterranean site reproduced larger carry-over effects of soil water. Irrigation, N supply, cover crops and atmospheric [CO2] showed clearer effects than tillage and crop residue management. Model performance varied distinctly between crops showing the necessity to provide experimental data for model calibration also for less prominent crops

Ammonia volatilization from irrigated and non-irrigated winter wheat plots in the North China Plain - Quantification and modeling

China’s growing population led to a drastic intensification of agriculture and livestock production in the last 50 years. Excessive mineral nitrogen (N) fertilizer application and intensive livestock production cause high N losses to the environment. Pathways of N losses may include gaseous N emissions via nitrification/denitrification (N2O, N2), ammonia (NH3) volatilization, nitrate leaching and surface run-off from soils. Ammonia emissions are one of the most important N loss pathways in the North China Plain (NCP) contributing to soil acidification, eutrophication of ecosystems and causing human health problems through combining with particles in the atmosphere which also impair visibility. For developing mitigation measures in a winter wheat cropping system, systematic measurements of NH3 volatilization were conducted in the NCP in Zhengding, 260 km southwest of Beijing. Ammonia emissions were measured with the calibrated Dräger-Tube method during the main crop growing season of winter wheat from April to June 2016. The treatments included urea and urea followed by immediate irrigation. Additionally, soil samples were taken from three depth increments (0-30, 30-60 and 60-90 cm) before and after fertilization and the NH3 volatilization was simulated with the HERMES model. The soils showed highest mineral nitrogen (Nmin) contents of up to 340 kg ha-1 (0-90 cm) after fertilization. A decrease in the calcium carbonate content and soil pH in topsoils (0-20 cm) (pH: 6.7) compared to subsoil horizons (pH: 7.7) was attributed to the long-term application of ammonium-based fertilizers as well as to high atmospheric deposition rates of ammonium and sulfuric compounds. Urea applied to winter wheat showed an NH3 loss equal to 22% the of applied N. Application of urea to winter wheat followed by irrigation yielded a reduction of the NH3 volatilization to 0.1% of the applied N. An improved N management based on the soil Nmin content is recommended to improve nitrogen use efficiency and to reduce N losses to the environment. Irrigation after fertilization can be recommended for reduction of NH3 volatilization, provided that other N loss pathways are of minor importance. The NH3 volatilization sub-module of the HERMES model enabled to simulate ammonia volatilization in the NCP satisfactorily. It is suggested to validate the model with further data sets from the NCP or from regions with comparable conditions

Energiepflanzenanbau für Biogasanlagen: Das Zweikulturnutzungssystem – ganzjähriger Bodenschutz und Reduzierung von Nitratausträgen bei stabilen Erträgen

Die Folge einer einseitigen Energiepflanzenproduktion mit Mais wären zunehmende Anbauprobleme und Umweltgefährdungen (Bodenerosion, Nitratauswaschung, Krankheiten und Schädlinge, vermehrter Pflanzenschutzmitteleinsatz). Zweikulturnutzungssysteme stellen eine Alternative dar, die neben hohen und sicheren Erträgen Umweltbelastungen und Anbau-probleme reduzieren bzw. vermeiden. Der Beitrag stellt die Vorteile solcher Systeme im Hinblick auf die oben genannten Problemfelder vor und vergleicht die Erträge mit konventionellen Hauptfruchtsystemen

Multi-wheat-model ensemble responses to interannual climate variability

We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981-2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R2 ≤ 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-term warming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts

Description of the compiled experimental data available in the MACSUR CropM database

The input data necessary for crop model simulations and data for their calibration/validation (and thus requirements for observations and measurements in suitable experiments) have been collected through out the project together with data for additional analysis of abiotic factors influencing yields. A list of possible dataset was collated in the first year of project however very few of the existing datasets were found usable for the crop model simulation as they fell short of the requirements defined in the part 2.3. However database has been populated as planned with the results of the ongoing MACSUR studies and will serve in the same way for the MACSUR 2 duration

Standortspezifische Modellierung von Pflanzenwachstum, Wasser- und N-Dynamik auf der Basis hochaufgelöster Bodensensordaten

Die Berücksichtigung von Bodenunterschieden innerhalb von Ackerschlägen bei der Bemessung von Düngergaben kann zu einer höheren Effizienz von Düngermaßnahmen führen, wenn einerseits Ertragspotentiale genutzt und andererseits Überdüngungen vermieden werden. Die technischen Möglichkeiten des Precision Agriculture werden jedoch bislang nur zögerlich genutzt, da die Erhebung der räumlichen Variabilität von Bodeneigenschaften mit erheblichem Aufwand verbunden ist und betriebswirtschaftlich wenig lohnend erscheint. Im BoNaRes Projekt I4S werden verschiedene Verfahren der Bodensensorik zur Erfassung wesentlicher Merkmale entwickelt und mit Modellen und Entscheidungsunterstützungsalgorithmen verknüpft. Erste Ergebnisse, die das Potential einer auf hochaufgelösten Bodendaten basierenden Simulation von Pflanzenwachstum sowie Bodenwasser und-Stickstoffdynamik im Vergleich mit hochaufgelösten Ertragskarten zeigen, werden vorgestellt. Diese basieren zunächst auf der bereits etablierten Messung der elektrischen Leitfähigkeit (EM-38) und der Nutzung von konventionell untersuchten Bodenproben in einem 50 m Raster. Hieraus lassen sich hochaufgelöste Karten zur Verteilung von Textur und Humusgehalt als Modelleingangsgrößen für 5000 Punkte innerhalb eines 20 ha Schlages ableiten. Die Konsistenz der Modellrechnungen wird anhand von Erträgen, Bodenwasser- und Nmin-Gehalten an 60 Rasterpunkten über drei Vegetationsperioden geprüft. Der Effekt unterschiedlicher Aggregierung sowohl von Boden als auch Ertragsdaten wird dargestellt

Is dry soil planting an adaptation strategy for maize cultivation in semi-arid Tanzania?

Agriculture has the greatest potential to lift the African continent out of poverty and alleviate hunger. Among the countries in sub-Saharan Africa, Tanzania has an abundance of natural resources and major agricultural potential. However, one of the most important constraints facing Tanzania’s agricultural sector is the dependence on unreliable and irregular weather, including rainfall. A strategy to cope with climate uncertainty in semi-arid regions is to proceed with the sowing of the crop before the onset of the rainy season. The advantage is that when the rains start, seeds are already in the soil and can begin immediately the process of germination. The objective of this paper was to assess the effectiveness of dry-soil planting for maize as an adaptation strategy in the context of a changing climate in Dodoma, a semi-arid region in Tanzania. For this assessment, the DSSAT crop model was used in combination with climate scenarios based on representative concentration pathways. A probability of crop failure of more than 80% can be expected when sowing occurs during the planting window (of 21 days) starting on 1st November. The next planting window we assessed, starting on 23rd November (which was still before the onset of rain), presented significantly lower probabilities of crop failure, indicating that sowing before the onset of the rainy season is a suitable adaptation strategy. Results also indicated that, despite not reaching the highest maize grain yields, fields prepared for dry-soil planting still produced adequate yields. The cultivation of several fields using the dry planting method is a strategy farmers can use to cope with low rainfall conditions, since it increases the chances of harvesting at least some of the cultivated fields. We conclude that dry-soil planting is a feasible and valid technique, even in scenarios of climate change, in order to provide acceptable maize yields in semi-arid Tanzania