Seguiment del contingut de nitrats al sòl i en planta en parcel·les comercials de panís al Pla d'Urgell

Abstract

This paper presents the partial results of the first year monitoring of soil and plant nitrate contents in commercial maize (Zea mays L.) in the Urgell canal irrigated area. The fields have been selected starting from the knowledge of the soils in the area and their spatial representativeness as main criteria. The excess of nitrogen in the area, present in the groundwater as well as in the irrigation water, is due to overfertilisation of the crops, of which maize is one of the most importants. In the monitored fields the applied nitrogen fertiliser ranges from 250 to 350 kg/ha. The first results show that the farmers applications are not related to the initially available soil nitrogen. They also show how the determination of nitrates in the lower part of the stem at the end of the cycle may help to show if the N availability has been excessive. The higher yields, 13.5 Mg/ha are the same with the lower fertilizer applications, with the lower soil N availabilities and with the lower contents of nitrates in the lower part of the stem (0.4 g NNO3/ kg). All of this show there is ample room to rationalize the nitrogen use.