Analysis of Agro-Environmental Sustainability of Drip Irrigation on Maize on Four Farms in the Veneto Plain (Northeastern Italy)

During the irrigation season 2023 a trial on four farms located in the Veneto region (northeastern Italy) was carried out. The main purpose was to evaluate the influence of different drip irrigation management on maize crop yields and water consumption by using some indices: DUlq (Distribution Uniformity of low quarter), IWUE (Irrigation Water Use Efficiency) RIS (Relative Irrigation Supply), CGR (Crop Growth Rate), Harvest Index (HI). The applied irrigation management was based on a semi-empirical criterion of crop evapotranspiration compensation throughout the growing season. The results showed that for a more efficient management of drip irrigation, the correct sizing of pipes and choice of drip lines are necessary as they improve the uniformity of water distribution to the crop; furthermore, the use of irrigation advisory systems to support the farmer’s choices in relation to crop needs is essential. Analyses of the volumes of irrigation water distributed have shown that an excessive supply of water in relation to crop requirements does not lead to greater biomass development and higher yields, but only to greater wastage of water, resulting in low efficiency caused by runoff and/or deep percolation. In addition, the results show that indices analysing environmental sustainability are crucial for comparing the management of different plots: for example, RIS showed that farm (1) applied more irrigation water (1279.8 mm) than the other farms (170 mm on average) and compared to crop requirements (491.8 mm), with estimated percolation losses of 947.4 mm, without showing higher yields and higher CGR values than the other farms. On one farm where it was possible to make a comparison with 2022 weather conditions and crop yields, it was shown how drip irrigation applied to maize can ensure acceptable yields without excessive water consumption, even in particularly dry years.