Geospatial technologies in spatially defined viticulture: case study of a vineyard with Agiorgitiko variety in Koutsi, Nemea, Greece

Abstract

Context and purpose of the study – Geospatial technologies have significant contribution to viticulture, especially in small-scale vineyards, which require precise management. Geospatial data collected by modern technologies, such as Unmanned Aerial Vehicle (UAV) and satellite imagery, can be processed by modern software and easily be stored and transferred to GIS environments, highlighting important information about the health of vine plants, the yield of grapes and the wine, especially in wine-making varieties. The identification of field variability is very important, particularly for the production of high quality wine. Modern geospatial data management technologies are used to achieve an easy and effortless localization of the fields’ variability. The aim of this study is to record and investigate the variability of all factors (soil, relief, etc.) that affect the qualitative and quantitative yield of the vineyard and their correlation to the characteristics of yield.

Material and methods – The study area is located in Koutsi, a region of the Municipality of Nemea, which is a famous area for its early ripening vineyards. The 1.3 ha vineyard was planted in 1980 with the Black Nemea (Agiorgitiko) variety on 41B rootstock, with planting distances of 2.30 x 1.20 m and planting density of 362 stumps per 0.1 ha. The orientation of the planting lines is North to South. The vineyard was divided into 13 blocks of about 0.1 ha each, after its study by orthomosaic, collected from UAV, and taking into account the planting lines and its shape. From each block, soil samples were collected in areas with different color (macroscopic observation using UAV data), at 13 points, in two depths of 0-30 cm and 30-60 cm. Soil analysis showed that the soil is characterized as normal, heavy clayey, moderately alkaline, moderate in organic matter, adequately supplied with phosphorus (P), poor in potassium (K), slightly low in boron (B), and low to moderate levels of trace elements. Total calcium carbonate (CaCO3) ranges from 56 to 74%, except for one sampling site which is approximately 30%. Harvesting conducted in early September when Baume degrees were greater than 13o. UAV flights were conducted using the DJI Matrice 100, DJI Phantom 3 and Sensefly Ebee platforms. The sensors used for this study were Parrot Sequoia (bands: G (550nm), R (660nm), Red-Edge (735nm) and Near-Infrared (790nm), RGB) and a modified Go-Pro camera.

Results – The obtained UAV images were used to extract Digital Terrain Model (DTM) and orthomosaic. Altitude and slope were calculated in the vineyard using the DTM. The orthomosaic was used to observe the phenotypic characteristics of the vineyard, such as soil variation (e.g. soil color) and cultivation characteristics. Thus, it was possible to monitor the condition of the vineyard in order to schedule and apply the required cultivation techniques and procedures. Important observations have been also made through vegetation indices. Exporting indices, such as Normalized Difference Vegetation Index (NDVI) supplied valuable information on the vigor and plant health of the vineyard. Thematic maps related to fertilization, irrigation and plant protection were also created. Using this information, cultivation techniques were more efficient, because farmers could focus on plants which were less productive and in need of more nutrients. Finally, thematic maps were useful in delineating management zones, which is extremely beneficial to viticulture.