Vol. 76 No: 5

Title:
Nitrogen uptake of Brussels sprouts - validation of a model

Authors:
M. FINK and C. FELLER

pp: 615-619

Abstract:
To improve nitrogen (N) fertilizer recommendations for field vegetables, Feller and Fink (1996) developed a generic model to predict total N demand based on expected yield. The objective of the present study was to validate this model by using independent data for Brussels sprouts (Brassica oleracea L. var. gemmifera), a crop with a high N demand and a long growing time when compared with other vegetable crops. A field experiment was carried out where three N fertilizer levels were tested in all combinations with three cultivars that were considered to differ in total yield and, thus, in N demand. In addition, three Brussels sprouts crops with different planting dates were monitored in a grower's field. The model overestimated N uptake for N-limiting conditions, but for optimally fertilized Brussels sprouts crops, measured and estimated N uptake showed a close correlation (r2 = 0.96) when total yield was used as an input parameter for the model. Although the error of estimation (SE = 40 kg N ha^-1) was considerable, studies with other vegetable crops using this model showed this error can be even higher if other tools such as look-up tables are used for predicting N uptake.

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