Variable rate irrigation and nitrogen fertilization in potato; engage the spatial variation (potential)

The objective of the proposed POTENTIAL project was to increase N and water use efficiency in potato by co-scheduling of N and irrigation water. Special attention is paid to the spatio-temporal variation in water and N deficit in potato fields. To meet this objective innovative sensing solutions were used such as drones, satellites and geophysical soil scanners. During the POTENTIAL project, between 2017 and 2019, 11 experimental fields were set up in Belgium, 3 in the Netherlands and 3 in Denmark. On a part of the experimental fields a variation in water and N status was induced by applying varying doses of irrigation and fertilization. In another experiment the variation in the field was studied, without adding extra degrees of variation in water or nutrient input. In each field in situ data were collected. At the beginning of the growing season soil properties were determined. Soil Sampling was conducted every three to four weeks to measure soil water and nitrate concent over the growing season. Alongside with the soil observations stomatal conductance was measured using a porometer. This provided indidcations on plant water stress. Harvest quantity and quality was determined at the end of the growing season by taking yield samples. Regular drone flights were executed during the growing season. Drones were equipped with multispectral and thermal cameras. In addition, Sentinel-2 multispectral satellite imagery was used to schedule irrigation and N-fertilization in potato delivering images on a 5-day basis. From the drone and satellite images various vegetation indices were derived such as NDVI, ReNDVI, Clgr and Clre. The thermal camera permitted to derive temperature maps or calculation of the crop water stress index (CWSI).