Isik Öztürk

The AgMIP Coordinated Climate-Crop Modeling Project (C3MP): Methods and Protocols

Climate change is expected to alter a multitude of factors important to agricultural systems, including pests, diseases, weeds, extreme climate events, water resources, soil degradation, and socio-economic pressures. Changes to carbon dioxide concentration ([CO2]), temperature, andwater (CTW) will be the primary drivers of change in crop growth and agricultural systems. Therefore, establishing the CTW-change sensitivity of crop yields is an urgent research need and warrants diverse methods of investigation. Crop models provide a biophysical, process-based tool to investigate crop responses across varying environmental conditions and farm management techniques, and have been applied in climate impact assessment by using a variety of methods (White et al., 2011, and references therein). However, there is a significant amount of divergence between various crop models’ responses to CTW changes (R¨otter et al., 2011). While the application of a site-based crop model is relatively simple, the coordination of such agricultural impact assessments on larger scales requires consistent and timely contributions from a large number of crop modelers, each time a new global climate model (GCM) scenario or downscaling technique is created. A coordinated, global effort to rapidly examine CTW sensitivity across multiple crops, crop models, and sites is needed to aid model development and enhance the assessment of climate impacts (Deser et al., 2012)...

Climate effects on crop yields in the Northeast Farming Region of China during 1961–2010

Crop production in the Northeast Farming Region of China (NFR) is affected considerably by variation in climatic conditions. Data on crop yield and weather conditions from a number of agro-meteorological stations in NFR were used in a mixed linear model to evaluate the impacts of climatic variables on the yield of maize ( Zea mays L.), rice ( Oryza sativa L.), soybean ( Glycine max L. Merr.) and spring wheat ( Triticum aestivum L.) in different crop growth phases. The crop growing season was divided into three growth phases based on the average crop phenological dates from records covering 1981 and 2010 at each station, comprising pre-flowering (from sowing to just prior to flowering), flowering (20 days around flowering) and post-flowering (10 days after flowering to maturity). The climatic variables were mean minimum temperature, thermal time (which is used to indicate changes in the length of growth cycles), average daily solar radiation, accumulated precipitation, aridity index (which is used to assess drought stress) and heat degree-days index (HDD) (which is used to indicate heat stress) were calculated for each growth phase and year. Over the 1961–2010 period, the minimum temperature increased significantly in each crop growth phase, the thermal time increased significantly in the pre-flowering phase of each crop and in the post-flowering phases of maize, rice and soybean, and HDD increased significantly in the pre-flowering phase of soybean and wheat. Average solar radiation decreased significantly in the pre-flowering phase of all four crops and in the flowering phase of soybean and wheat. Precipitation increased during the pre-flowering phase leading to less aridity, whereas reduced precipitation in the flowering and post-flowering phases enhanced aridity. Statistical analyses indicated that higher minimum temperature was beneficial for maize, rice and soybean yields, whereas increased temperature reduced wheat yield. Higher solar radiation in the pre-flowering phase was beneficial for maize yield, in the post-flowering phase for wheat yield, whereas higher solar radiation in the flowering phase reduced rice yield. Increased aridity in the pre-flowering and flowering phases severely reduced maize yield, higher aridity in the flowering and post-flowering phases reduced rice yield, and aridity in all growth phases reduced soybean and wheat yields. Higher HDD in all growth phases reduced maize and soybean yield and HDD in the pre-flowering phase reduced rice yield. Such effects suggest that projected future climate change may have marked effects on crop yield through effects of several climatic variables, calling for adaptation measures such as breeding and changes in crop, soil and agricultural water management.

A Case Study on Changing Livelihood Strategies of the Community of Ban Non Sao-e Village, Nakhon Ratchasima Province, Thailand

In an attempt to better understand household response to natural and socio-economical conditions in a rural community, this paper examines the livelihood strategies developed by members of the village of Ban Non Sao-e. Using data compiled from 44 household surveys, I investigate how the village community adapted to these new livelihood strategies, in which landownership and farming become gradually less important. I examine the income-generating capacity of each occupation, as well as the average income of households. Results indicate that those who own land have a higher average income than those who do not. The respondents stressed that agricultural production was not a viable income-generating strategy for most households in the study area. Landownership, access to water resources and institutional financial sources all have a significant effect on average income. The case study suggests that a purely economic or natural approach is not sufficient to explain livelihood strategy changes, especially in rural communities.Dans le but de mieux comprendre la réponse des ménages aux évolutions des conditions naturelles et socio-économiques dans une communauté rurale, cet article examine les stratégies de subsistance des membres du village de Ban Non Sao-e. En utilisant les données de 44 enquêtes auprès de ménages, je cherche à voir comment la communauté villageoise s’adapte aux nouvelles stratégies de subsistance, dans lesquelles la propriété foncière et l’exploitation agricole prennent de moins en moins de place. J’examine la capacité à générer des revenus de chaque type d’activité, ainsi que le revenu moyen des ménages. Les résultats indiquent que les propriétaires fonciers ont des revenus moyens supérieurs à ceux qui ne sont pas propriétaires. Les enquêtés soulignent que la production agricole ne correspond pas à une stratégie fiable pour générer des revenus en ce qui concerne la plupart des ménages dans la zone de l’étude. La propriété de la terre, l’accès à l’eau et les sources de financement institutionnelles ont un effet significatif sur le revenu moyen. L’étude de cas suggère qu’une approche purement économique ou naturelle n’est pas suffisante pour expliquer les changements dans les stratégies de subsistance, tout particulièrement dans les zones rurales.

Simulation of leaf photosynthesis of C3 plants under fluctuating light and different temperatures

An induction-dependent empirical model was developed to simulate the C3 leaf photosynthesis under fluctuating light and different temperatures. The model also takes into account the stomatal conductance when the light intensity just exceeds the compensation point after a prolonged period of darkness (initial stomatal conductance,

Multi-model uncertainty analysis in predicting grain N for crop rotations in Europe

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Adapting maize production to drought in the Northeast Farming Region of China

). The model was parameterized for both Chrysanthemummorifolium and Spinacia oleracea by artificially changing the induction states of the leaves in the climate chamber. The model was tested under natural conditions that were including frequent light flecks due to partial cloud cover and varying temperatures. The temporal course of observed photosynthesis rate and the carbon gain was compared to the simulation. The ability of the current model to predict the carbon assimilation rate was assessed using different statistical indexes. The model predictions were accurate but the model slightly underestimated the actual overall carbon gain. The accuracy of the simulation was largely dependent on the parameters that were calculated for the particular plant species, of which the simulation is intended for. In particular, the rate of change of induction and the initial stomatal conductance were found to be highly important and these were species-specific parameters for the predictions. The model is suitable for estimating instantaneous leaf CO2 assimilation for different herbaceous plant species under dynamic environmental conditions. It can be simply calibrated for other crops, by estimating the individual parameters.