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Title: CROPSYST VB-SIMPOTATO, A CROP SIMULATION MODEL FOR POTATO-BASED CROPPING SYSTEMS: 2. EVALUATION OF NITROGEN DYNAMICS

Author
item Alva, Ashok
item MARCOS, JAVIER - WSU, PULLMAN
item STOCKLE, CLAUDIO - WSU, PULLMAN
item Reddy, Vangimalla
item Timlin, Dennis

Submitted to: International Crop Science Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2004
Publication Date: 9/27/2004
Citation: Alva, A.K., Marcos, J., Stockle, C., Reddy, V., Timlin, D.J. 2004. CROPSYST-VB-SIMPOTATO, a crop simulation model for potato-based cropping systems: 2. Evaluation of nitrogen dynamics. International Crop Science Congress Proceedings. (On CD)

Interpretive Summary: In a companion paper presented at the International Crop Science Congress, development of a potato growth simulation model, i.e. SIMPOTATO, and integration of this model with CROPSYST model was described. The integrated model facilitates an evaluation of fate and transport of nitrogen in a potato rotation system. In this paper, the above model simulation was compared with the two years of field data using Ranger Russet potato cultivar grown in a sandy soil in southeastern Washington state. The model simulation of N uptake compared reasonable well with the measured crop uptake. The predicted tuber yield did not match very well with the actual measured yields. Model simulations showed a large quantity of N unaccounted in the crop root zone (0.6 m) at the end of potato cropping. Further studies and model simulations will be conducted to evaluate the fate of this unaccounted N.

Technical Abstract: Application of CROPSYST-SIMPOTATO model was evaluated for potato production systems in the Pacific Northwest of the United States. Model predictions showed that unaccounted N at the end of the crop growth varied from 102 to 170 kg/ha in the year 2001, and were much greater in the year 2002. Further studies are needed to validate the fate of this unaccounted N. Results also demonstrated the use of model predictions to assess N transport and losses under different water and N management practices. Therefore, the model simulation can be used to predict the fate and transport of N under different N and water management options. This information is useful to optimize the rate and timing of N and water applications to support the maximum production, while minimizing the negative effects of N losses.