A dynamic model for the effects of potassium and nitrogen fertilizers on the growth and nutrient uptake of crops

Abstract

SummaryA dynamic model has been derived to predict the day-to-day changes in the growth and nutrient composition of crops grown in the field with different levels of nitrogen and potassium fertilizer. Equations are included in the model to represent processes such as re-distribution of nutrients down the soil profile after rain or evapotranspiration, transformations between the various forms of potassium, transport of potassium ions through the soil to the roots and the dependence of growth and nutrient uptake on incoming radiation, plant composition, and soil water stress.The model was tested by using it to forecast the responses of a test crop, cabbage, to fertilizers in four separate field experiments at WeUesbourne. From data describing the initial soil conditions and weights of the plant, the soil and crop characteristics and the daily weather conditions, the model correctly predicted the pattern of responses in each experiment, although, in some instances the absolute values of the theoretical and experimental yields differed somewhat. Of special significance was the ability of the model to forecast the effects of different weather conditions on crop response and the interactions between the effects of N and K fertilizers on the growth and chemical composition of plants.