NIL-N-PLOTS: A SYSTEM TO ESTIMATE THE AMOUNT OF THE NITROGEN TOP DRESSING OF VEGETABLES

Although a lot is known about the nitrogen demand of vegetable crops, many farmers still determine fertiliser requirements by a ‘rule of thumb’. Since no soil analysis is carried out, there is no accounting for the mineral N in the rooted layer.
Nil-N-plots (where a small part of the field remains without fertiliser) offer a simple method of estimating the N_min content of the soil and a way to adapt top-dressing for vegetable crops.
The rest of the field receives a normal basal-dressing (enough for the period of growth between planting/sowing and top-dressing). The amount of top-dressing is determined by the time it takes for the appearance and the intensity of N deficiency symptoms to become visible in the Nil-N-plot, compared to the rest of the field.

In a 2-year field experiment with 12 different vegetable crops, the Nil-N-plots method was compared with the N_min method by taking soil samples and adding fertiliser up-to the N_min target value.
There was no decrease in yield when using Nil-N-plots method.
However, when the N_min content of the soil was high at the beginning, the total fertiliser applied was higher than the N_min target value.
Nevertheless Nil-N-plots are better than using ‘rules of thumb’.

International Conference on Environmental Problems Associated with Nitrogen Fertilisation of Field Grown Vegetable Crops

U. Weier, U. van Riesen, H-C. Scharpf

nitrogen fertilisation, nitrogen fertiliser requirement, fertilisation window

https://doi.org/10.17660/ActaHortic.2001.563.4