Analysing potato response to subsurface drip irrigation and nitrogen fertigation regimes in a temperate environment using the Daisy model

Abstract

Growing potatoes in temperate regions often leads to nitrogen (N) leaching, however this could be significantly reduced with drip irrigation and nitrogen fertigation if the timing and amounts of the applications matched the crop demand. Determination of when and how much to apply is not straightforward, particularly because the N mineralisation during the potato-growing season is unknown. The present study aimed at providing a solution by the means of a well-calibrated crop model. A comprehensive dataset from a two year experiment on subsurface drip irrigated and N-fertigated potato was used to calibrate and validate the Daisy model with focus on potato crop parameters. The experiment included two irrigation regimes combined with five different N fertigation levels. The calibrated model simulated LAI evolution, crop growth, N uptake and final tuber dry matter and N yield satisfactorily with discrepancies between the simulated and measured variables when simulations were evaluated treatment by treatment. The root mean squared error (RMSE) of the simulated tuber dry matter yield were 0.57 and 0.69 t DM ha-1 for the Folva cultivar in 2013 and Sava cultivar in 2014, respectively. For tuber nitrogen yield, RMSE of the model simulations were 9.7 and 12.8 kg N ha-1 in 2013 and 2014, respectively. Results demonstrated that the calibrated Daisy model could be used as a DSS tool for the optimal irrigation and fertigation of Folva and Sava potato cultivars. Compared to the experimental data the same tuber dry matter yield was simulated with substantial savings 30–55% and 35–50% of irrigation water and N fertiliser, respectively. Results indicated an overestimation of bare soil evaporation, and inconsistences in the simulated effects of water and N stresses on the crop.