ISHS Acta Horticulturae 260: International Symposium on Growth and Yield Control in Vegetable Production
CONTROLLING OUTPUT LEVEL IN WHITE CABBAGE BY ASSESSING N-FERTILIZATION ON THE BASIS OF SOIL AND PLANT ANALYSES |
| Authors: | P.-J. Paschold, Ch. Scheunemann |
| Abstract:
On the basis of flexible N-fertilization within the framework of computer-assisted crop management in late white cabbage we investigated whether start dressing could be calculated on the basis of the Nan-content of the soil and whether the times and frequencies of top dressings can be based on plant analyses. Our investigations, which were carried out over several years on three different kinds of soil, were based on model tests, on the growth rates, the nitrate contents and the contents of inorganic introgen in the soil. The results obtained in a test year bore out the fact that, in comparison with a fixed fertilizing routine, calculation of start dressing on the basis of the Nan-content of the soil and calculation of top dressing on the basis of plant analyses allow the more sparing use of N-fertilizer without reducing output levels. The nitrate content of the plant sap serves as the criterion whereby the level of top dressing is controlled. The values obtained analytically are compared with optimal nitrate levels indicating when the next top dressing will be necessary. In the tests described below we were able to reduce start dressing and to eliminate one top dressing and saved 110 kg N/ ha compared to a fixed dressing routine, without reducing output levels. At the same time the nitrate content in the harvested crop was reduced. | |
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