Keith-Pembleton
commented
1 year ago @hut104 do you need any LAI data for forage rape? I have 2 years of LAI for two sowing rates from Elliott in Tasmania sitting on a drive gathering dust. One of those years was with and without irrigation.
Also it would be good if this could do turnips and pasja (leafy turnips) but they have a different structure with their bulbs so I guess this would be beyond your scope. I would have some limited data sets to support both if you want them.
Forage Brassicas are important options for mixed farming systems and recent research has completed into developing models for these crops. These researchers have now provided the data and model parameterisations developed wtihin this project for incorporation into APSIM as described in the APSIM licence agreement.
The model parameterisation developed within the project will be used to create a new Forage Brassica model within APSIM Next Generation using the newly-published canola model as a base class so that the new model will gain leverage from the existing and ongoing work on canola crop model development, which also includes work on grazing of canola as a dual-purpose crop.
Lucinda J. Watt, Lindsay W. Bell, Keith G. Pembleton, A forage brassica simulation model using APSIM: Model calibration and validation across multiple environments, European Journal of Agronomy, Volume 137, 2022, 126517, ISSN 1161-0301, https://doi.org/10.1016/j.eja.2022.126517. (https://www.sciencedirect.com/science/article/pii/S116103012200065X) Abstract: Forage brassicas have historically been used in high rainfall/irrigated temperate livestock systems, but there is increasing interest in diverse forage brassicas in drier mixed crop-livestock farming systems. Computer-based modelling is an important decision support tool used in agriculture to explore the adaptability of crops to different climates and agronomic management practices, but existing modelling tools for forage brassicas are limited to temperate environments. We parameterised the APSIM (Agricultural Production Systems Simulator) model for four forage brassica genotypes, including three diverse forage rape cultivars and a raphanobrassica. The model was calibrated using two experiments with repeated measures of biomass components, nutritive value, and leaf and canopy development. We then tested the model extensively using data from a diverse set of environments within Australian and New Zealand (23 sites across four agro-climatic zones). Model predictions of biomass were good for all the genotypes (NSE > 0.60, Nash-Sutcliffe efficiency; RMSE ~1.5 t DM/ha, root mean square error). Predictions of metabolisable energy yield were satisfactory for all genotypes (NSE 0.43–0.73; RMSE ~17.8 GJ ME/ha) but forage dry matter digestibility (DMD) were poorly predicted due to the small variation in observed data. Our robust and widely tested model can be confidently used to predict forage productivity of common and new forage brassicas across a wide range of production environments and agronomic management practices. This model will enable future work to develop a better understanding of the potential value of these important forage crops for livestock production systems. Keywords: Mixed farming systems; Forage rape; Raphanobrassica; Canola; Forage productivity