Simulation of C and N dynamics in soil and plants

1. Simulation of C and N dynamics in soil and plants R.A. Poluektov & V.V.Terleev Agrophysical Research Institute, St.-Petersburg, Russia

2. Model structure

3. Input data

4. State variables and output

5. Submodels

6. Shell structure of AGROTOOL

7. Model features

8. Model identification consists of 5 steps:

9. Parameters controlling temp of plant development:

10. Water stress function Correction of dry matter accumulation Argument of water stress function Stress function

11. Calculation of root:shoot ratio (Two flows model)

12. C and N transformation in soil

13. Calculation of crs Distribution of PrimAss: N demand by shoot and root N uptake by roots: N – balance:

14. Determination of root:shoot ratio 1- N-dependence of crop, 2 – N-uptake by roots

15. Dependence of root:shoot ratio on N-doze 1- flowering phase, 2 – full ripening phase

16. 0,9 0,8 0,7 0,6 0,5 Root:shoor ratio 1 0,4 2 0,3 3 0,2 0,1 0,0 0 10 20 30 40 50 60 70 80 90 Days of vegetation starting from sowing Dynamics of root:shoot ratio by various N-fertilization 1- variant without N, 2 – N=45 kg ha-1, 3 – N=90 kg ha-1

17. Model of water retention curve where volumetric soil moisture, matrix potential, MH maximum hygroscopy, SP saturation point, a, b empirical parameters.

18. Variants of calculation of hydrological constants , , , , r- soil bulk density, rS - solid phase density, MH – maximum hygroscopy, SP - saturation point, WP – wilting point, FC – field capacity, LC – lower capillary moisture, UC – upper capillary moisture.

19. Calculation of water retention curve for the soil of Men'kovo experimentation station using the following experimental data: r, rS , MH. 1 –water retention curve, 2 – specific water capacity, 3 – dependence of UC on yUC, 4 - dependence of LC on yLC

20. Comparison of calculated and experimental data o– experimental points, -.- - interpolated curve, curve calculated using experimental data

21. Computer system for estimation soil hydraulic parameters

22. Estimation of Badlauchstadt pedotransfer functions • This program was used for estimation of the parameters included in pedotransfer functions. The experimental data for soil texture and saturated hydraulic conductivity were used for this purpose. Two additional data, apart from available MHandSP, were necessary for estimation of the pF-curve parameters. Such hydraulic soil parameters as field capacity (FC) and wilting point (WP) were chosen for this purpose. The comparison of simulated pF-curves with experimental data is presented in the following Figs.

23. Comparison between simulated water retention curves and experimental data sets presented by Franko et al. (site Badlauchstadt)

24. Comparison of simulated and real winter ray grain yield (Men’kovo experimentation station)

25. Dependence of spring barley grain yield on N-dose (Men’kovo experimentation station)

26. Nitrates leaching (Men’kovo experimentation station)

27. Yield and dry mass

28. Yield and dry mass

29. Yield and dry mass

30. Water status

31. Water status

32. Results of statistical treatment for water content

33. Results of statistical treatment for dry mass

34. Conclusion • Generally, there are externally few things in the World, which we really anything know about. In the most cases it only seems to us that we know. Kharuki Murakami “Hunting on sheep”

35. Thank you