Over de optimale stikstofvoeding van granen

Oats grown in culture solution showed an 'active' mineral uptake, which after ripening of the panicles benefited the newly formed tillers only. Ripening of the plants after interrupting nutrient supply depended on the stage of floral development. The longevity of a cereal was governed by the demand for assimilates by the inflorescences from the assimilating organs and the continuous supply of nutrients to these organs. Further experiments yielded the postulate that N supplied to a given organ led to protein synthesis, enabling this organ to accumulate and retain assimilates and withstand the drain on assimilates imposed by younger organs.
Distribution and redistribution of dry matter and 15N-labelled N over different plant parts and the effect of environment on nitrogen utilization and redistribution was studied.

Pot trials and concurrent field experiments with ample and continuous supply of N showed that maximum yield was attained with the same yield composition, pattern of N uptake and the same dry matter production per unit N uptake. At maximum yield, as a basis for comparison, N uptake by cereals in the field was 120- 150 kg N per ha, for Mitscherlich pots 1800-3000 mg N per pot. In most pot trials N level was far below that of field experiments.