Testing different CO₂ response algorithms against a FACE crop rotation experiment

Abstract

a b s t r a c tA soil-crop-environment model was used to describe the combined effects of atmospheric carbon dioxide concentration [CO 2 ], temperature and precipitation on different agricultural crop species. Within this model, a set of algorithms describing CO 2 response to photosynthesis and crop water use efficiency, which differed in complexity and parameter requirements, was tested for its suitability to explain crop growth responses and soil moisture dynamics observed over 6 years in a crop rotation (winter barley, sugar beet and winter wheat) with two cycles under normal and elevated atmospheric CO 2 levels (FACE experiment; Weigel and Dämmgen [46]).All algorithms were able to describe an observed increase in above-ground dry matter for all crops in the rotation, with Willmott's index of agreement (IoA) ranging between 0.93 and 0.99. Increasing water use efficiency with rising CO 2 was also successfully portrayed (IoA 0.80-0.86). A combination of a semi-empirical Michaelis-Menten approach, describing a direct impact of CO 2 on photosynthesis, and a Penman-Monteith approach with a simple stomata conductance model for evapotranspiration yielded the best simulations. This combination is therefore considered suitable for the description of yield responses to rising [CO 2 ] at the regional level. However, the performance of all tested algorithms was only marginally different at 550 ppm CO 2 .

Crop rotation modelling—A European model intercomparison

“…Thus, by applying a 15-model ensemble (where most models used the approach of radiation use efficiency), we were able to reproduce the results generated in other modelling studies that simulated the effect similarly well (Kartschall et al, 1995;Nendel et al, 2009;Tubiello et al, 1999).…”

Atmospheric CO2 fertilization effects on biomass yields of 10 crops in northern Germany

“…In a comparison of several different approaches to determine photosynthesis rates in C 3 -plants against actual results from FACE experiments (Nendel et al, 2009), the approach suggested by HOFFMANN did show the best results when estimating dry matter, yield, LAI and soil moisture changes.…”

Ecosystem responses to elevated CO<sub>2</sub> using airborne remote sensing at Mammoth Mountain, California

“…Kimball et al (1998) found a slight increase in ET in a FACE experiment over cotton fields, 20 but that increase was within the error of the ET estimation, and so was not deemed statistically significant. In contrast, Nendel et al (2009) found a decrease in ET, and an increase in dry above-ground biomass over a FACE crop rotation experiment. In this study, we found a decrease in ET.…”