Year-to-year variations in crop yields can have major impacts on the livelihoods of subsistence farmers and may trigger significant global price fluctuations, with severe consequences for people in developing countries. Schaphoff, Sibyll Schewe, Jacob Schmid, Erwin Warszawski, Lila Levermann, Anders Understanding the weather signal in national crop-yield variabilityįrieler, Katja Schauberger, Bernhard Arneth, Almut BalkoviÄ, Juraj Chryssanthacopoulos, James Deryng, Delphine Elliott, Joshua Folberth, Christian Khabarov, Nikolay Müller, Christoph Olin, Stefan Pugh, Thomas A. These risks are subsequently related to crop damage. ![]() Risks of combined heat and moisture deficit stress appear during the summer. Effects of heat stress therefore have to be combined with moisture availability such as the precipitation deficit or the soil water balance. Crops short of water close their stomata, lose their evaporative cooling potential and ultimately become susceptible to heat stress. The response to rising temperatures depends on the crop's capability to condition its microenvironment. ![]() Distribution patterns of VPD and ET0 have relevant impacts on crop yields. The average daily vapour pressure deficit (VPD) and reference evapotranspiration (ET0) during the growing season is significantly lower (p < 0.001) and has a higher variability before 1988 than after 1988. The risk profiles were subsequently confronted with yields and yield losses for the major arable crops in Belgium, notably winter wheat, winter barley, winter oilseed rape, sugar beet, potato and maize at the field (farm records) to regional scale (statistics). Risk profiles and associated return levels were obtained by fitting generalized extreme value distributions to block maxima for air humidity, water balance and temperature variables. Since crop development is driven by thermal time and photoperiod, a regional crop model was used to examine the likely frequency, magnitude and impacts of frost, drought, heat stress and waterlogging in relation to the cropping season and crop sensitive stages. The hypothesis is that extreme and adverse weather events can be quantified and subsequently incorporated in current crop models. The impact is largest during the sensitive periods of the farming calendar, and requires a modelling approach to capture the interactions between the crop, its environment and the occurrence of the meteorological event. Simulation results show that IRSIS model tends to over predict grain yields of maize, .Īdverse weather impacts on arable cropping systemsĭamages due to extreme or adverse weather strongly depend on crop type, crop stage, soil conditions and management. ![]() Input for the models comprised of weather, crop and soil data collected from five selected stations. IRSIS and CRPSM models were used in this study to see how closely they could predict grain yields for selected stations in Tanzania. Validation of crop weather models for crop assessment arid yield. The model utilizes a series of efficiency parameters, each of which reflect the fraction of possible photosynthetic rate permitted by the different weather elements or crop architecture. Ī theoretical mathematical model for describing crop photosynthetic rate in terms of the weather variables and crop characteristics is proposed. Simple model for crop photosynthesis in terms of weather variables.
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