Articles
THE ROLE OF N FERTILIZATION IN RELATION TO THE KEEPING QUALITY OF ONION
In the first place I must say, that we have had some very nice experiments, in co-operation with Dr Preters of the famous Fertilizing Institute at Harm /near Gromingen/ in Holland.
In the second place I must tell you, that I got the graphes just before departure from the Netherlands.
As, it is quiete impossible to inform myself more in details from here, I can only tell you about our work, what I remember myself.
During the growing seasons in 1978/79 80/81 and 82 we had totally 37 field-experiments, spread over different onions-areas in the Netherlands.
The main scope was to know, if it is possible to opply nitrogen-fertilizer for onions, on the base of the quantity of mineral-nitrogen, as found by means of soil-analysis.
First of all we found, that there is a very, very great variation in the quantity of mineralized nitrogen in the soil/up to 90 cm deep/ in all those years in different places.
| This variation has been: | 1978 | 17 – 167 | kg min N/ha |
| 1979 | 45 – 139 | “ | |
| 1980 | 53 – 162 | “ | |
| 1981 | 36 – 127 | “ | |
| 1982 | 36 – 194 | “ |
We used the following doses of nitrogen during the years after zero, respectively 50–100–150 and 200 kg N/ha.