The role of superabsorbent hydrogel in bean crop cultivation under deficit irrigation conditions: A case-study in Southern Italy

This study was planned for investigating the role of biodegradable cellulose-based superabsorbent polymers in the management of water irrigation systems in bean crop cultivations in areas affected by water scarcity. The paper focused the attention on the bean crop (Phaseolus vulgaris L.) cultivated in the Mediterranean region during the summer seasons characterised by optimal thermal conditions, but with a systematic absence of water for irrigation due to the low level of precipitations. We analysed the performance and the role of cellulose-based superabsorbent in the irrigation systems where it is necessary to ensure a continuous and adequate level of soil moisture. Based on crop evapotranspiration demand calculated from the analysis of weather data, deficits and full-drip irrigation strategies were applied. Full and deficit irrigation treatments received 100, 70 and 50% of evapotranspiration demand, respectively. In addition, given amounts of superabsorbent polymer granules (SAPs) were mixed with the soil, in particular, 0, 5 and 10 g were added to the soil for full and deficit irrigation treatments.This study highlights a significant difference between the treatments, the combination of deficit irrigation and soil amendment hydrogel leads to a maximization of the crop water productivity index. In fact, the highest water use efficiency indexes were obtained with soil amendment hydrogel strategies under water deficit irrigation conditions. Our findings could be useful to optimize the consume of water resources in bean crop cultivations in the Mediterranean regions.