DY-FERT HC: A LOW-INPUT DYNAMIC APPROACH TO MANAGING FERTIGATION ON A DAILY BASIS

Abstract

Fertigation of processing tomatoes is normally managed on the basis of standard nutrient uptake curves and the amount of nutrients to be supplied is scheduled during the crop cycle according to an average plant phenology which does not take account of changes in the duration of growth stages. The DY-FERT model calculates the nutrient uptake (N, P, K, Ca, Mg) on a daily basis in relation to the daily accumulation of dry matter (DM). An above-ground dry matter accumulation curve was calculated on a Growing Day Degree (GDD) basis using data from the Qualitom project database and calibrated using data from a typical tomato growing area in northern Italy. The observed and simulated data were strongly correlated (R 2 = 0.894) and the modelling efficiency was very high (EF = 0.887) The nutrient uptake ratio changes during the season according to 5 growth stages were identified as DM curve slope changes. The results of a seven-year simulation showed significant yearly differences in the duration of each growth stage as measured by changes in GDD accumulation. Moreover, the NPK supply strategies simulated with DY-FERT differed greatly from the Standard ones. The model was field tested in 2000, resulting in more DM m -2 and a higher fruit partitioning of total DM.