![soil mineral nitrogen apsim soil mineral nitrogen apsim](https://www.researchgate.net/profile/John-Dimes/publication/252960786/figure/fig4/AS:647500620902402@1531387586890/Schematic-representation-of-the-processes-affecting-soil-organic-matter-and-nitrogen.png)
Sensitivity analysis showed that improving the definition of the model parameter of crop N2 fixing capacity (the potential to fix atmospheric N2 per unit above-ground DM unit: gNgâ∡ DM) would improve the simulations of NFE.
![soil mineral nitrogen apsim soil mineral nitrogen apsim](https://www.researchgate.net/profile/Monoranjan-Mohanty/publication/281547764/figure/fig1/AS:650470313971714@1532095616582/Diagram-of-APSIM-SoilN-module-showing-transformation-of-C-and-N-in-each-soil-layer-Solid.png)
However, the simulations of N2 fixation efficiency (NFE, calculated as fixed N2 per unit above-ground dry matter (DM unit: gNkgâ∡ DM) were much less accurate, especially for lupin. The model was also able to simulate the responses of N2 fixation by chickpea and peanut to differences in soil mineral N status. In general, the absolute amount of N uptake and N2 fixation in above-ground biomass (unit: kghaâ∡) were reasonably well simulated, with 92% of the variation in observed N accumulation in above-ground biomass and 84% in N2 fixation being explained by APSIM. The simulations varied in location, cultivar, sowing date, climate, soil type, water regime (irrigated or dryland) and starting soil N and applied fertiliser N in tropical, subtropical, semiarid and Mediterranean environments across Australia.
![soil mineral nitrogen apsim soil mineral nitrogen apsim](https://0.academia-photos.com/attachment_thumbnails/74508723/mini_magick20211110-31099-1je047e.png)
The parameterised model was tested for the simulation of N uptake and N2 fixation in above-ground biomass of four crop legumes (lupin, chickpea, field pea and peanut). However, the model performance has not been evaluated in simulating the dynamic processes of N accumulation and N2 fixation.
Soil mineral nitrogen apsim simulator#
The growth and development of legumes and their impact on soil N fertility can be simulated by the Agricultural Production Systems Simulator (APSIM). It is important to quantify the nitrogen (N) uptake and dinitrogen (N2) fixation of legumes and estimate the N contribution that these crops make to subsequent crops for sustainable agricultural production.