Norwegian Journal of Agricultural Sciences : N-requirements of cabbage crops grown on contrasting soils

Abstract

A nitrogen response simulation mode! developed at Horticulture Research International (England) was used to explain the differences in yields obtained in N fertilizer trials with cabbage grown on soils with high and low water-holding capacity and different irrigation regimes. The mode! showed that higher N leaching on the sandy soil was responsible, due to both higher irrigation intensity and more rainfall. Simulations showed that split fertilizer dressing was unnecessary on loam soil, but that it was likely to be beneficial on sandy soil. Model predictions of final yields and N concentrations were generally in agreement with measured values, but N concentrations in early season were overestimated. Sensitivity analysis of the model suggested that the parametre used to determine net N mineralisation is of crucial importance in the calculation of nitrogen responses.