Dairy farm nutrient management model. 1. Model description and validation
Intensive dairy farming results in significant phosphorus (P) emission to the environment. Field data indicates that farm-gate P surplus is highly positive in Finland and strategies to mitigate the surplus are needed. The objectives of this study were to build a P cycle model for dairy farms (1) and to validate the model with independent field data (2). The dairy farm nutrient management model ("Lypsikki") described in this paper includes three sub-models: (1) soil and crop, (2) dairy herd and (3) manure management. The model is based on empirical regression equations allowing estimations of crop and milk yields in response to increased fertilisation and nutrient supply, respectively. In addition, the model includes a dynamic simulation model of the dairy herd structure and calculation of the farm-gate nutrient surplus. The model was validated with independent annual (average for 1-4Â years) farm-gate P surplus data from 21 dairy farms. Model simulations were conducted using two levels of soil productivity, mean (M) and low (L). The model validation indicated a strong relationships between model-predicted and observed farm-gate P surplus: (M: R2Â =Â 0.77 and L: R2Â =Â 0.80). The line bias between the model-predicted and observed data was negligible and insignificant (PÂ >Â 0.6) suggesting a robustness of the model. The mean biases were relatively high and significant (M: 4.7 and L: 1.8Â kg/ha, PÂ
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- Huhtanen, Pekka & Nousiainen, Juha & Turtola, Eila, 2011. "Dairy farm nutrient management model: 2. Evaluation of different strategies to mitigate phosphorus surplus," Agricultural Systems, Elsevier, vol. 104(5), pages 383-391, June.
- Buysse, J. & Van Huylenbroeck, G. & Vanslembrouck, I. & Vanrolleghem, P., 2005. "Simulating the influence of management decisions on the nutrient balance of dairy farms," Agricultural Systems, Elsevier, vol. 86(3), pages 333-348, December.
- van Calker, K. J. & Berentsen, P. B. M. & de Boer, I. M. J. & Giesen, G. W. J. & Huirne, R. B. M., 2004. "An LP-model to analyse economic and ecological sustainability on Dutch dairy farms: model presentation and application for experimental farm "de Marke"," Agricultural Systems, Elsevier, vol. 82(2), pages 139-160, November.
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