Assessment of the dynamic phosphate model PHOSMOD using data from field trials with starter fertilizer to cereals

Assessment of the dynamic phosphate model PHOSMOD using data from field trials with starter fertilizer to cereals

2006

E07304

Field trials are useful for achieving information about how crops respond to different fertilizer applications. However, the yield is normally only measured at the end of the growing season, and little information about growth and nutrient utilization during the season is obtained. With the aid of models it is possible to simulate plant growth and nutrient uptake from day to day. In the present paper, a mechanistic phosphate (P) model, PHOSMOD, was assessed using measured data from field fertilizer trials, in which spring barley Hordeum vulgare L.) was grown with various amounts and placements of fertilizer P under contrasting soil and weather conditions. PHOSMOD is developed by Greenwood et al. (2001a), mainly for vegetable crops and runs interactively at www.qpais.co.uk/phosmod/phos.htm. In the test data plant growth and plant P concentration were recorded at three stages of growth. After some adjustments, the model was able to reproduce the observed responses to band placed P and starter fertilizer in plant dry matter, and to predict differences between soil types in the responses to applied fertilizer. The main adjustments to the model were the inclusion of bulk density in the equation for calculating tortuosity, and modifications to the start and end of the growth curve in order to achieve a shorter period of P uptake. Based on the results from this study, PHOSMOD appears to be a promising tool for predicting effects of different P fertilization strategies, and will in our view be a useful aid for improving the fertilizer planning programs used in Norway today.\n \n \n \n

74(1):75-89, NUTRIENT CYCLING IN AGROECOSYSTEMS

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