A new irrigation controller to improve water use in the hard ornamental nursery stock industry in Italy

In the neighborhood of the city of Pistoia, central Italy, is located one of the largest container Hard Ornamental Nursery Stock (HONS) production centres in Europe. Water use efficiency (WUE) is one of main problem of these nurseries, mainly due to inaccurate irrigation scheduling, since almost all nurseries use simple timers to control irrigations. Plants are irrigated 1-4 times day-1 with irrigation events set periodically (every 1-4 weeks) by the growers based on their personal experience. This paper reports the results of a work performed to design, construct and test a simple and cost-effective irrigation control system (IRRIVIVA) for HONS nurseries. This system aims to reduce the growersRSQUO tendency to over-irrigate and the oscillations in the substrate moisture content, thus resulting in greater WUE and better crop performance (faster growth, less susceptibility to root-borne diseases, etc.). For this purpose, IRRIVIVA considers the day-to-day oscillation in reference evapotranspiration (ETo) and then crop evapotranspiration (ET). The IRRIVIVA system automatically adjusts, on a daily basis, the length of watering (i.e., irrigation dose) set by the grower on the time clock system using a correction coefficient (kET), which is as the ratio between the ETo of the previous day and the historical maximum ETo for that week of the year (EToh). In a validation experiment with container-grown red-tip photinia (Photinia × fraseri Dress) and cherry laurel (Prunus laurocerasus L.), the application of IRRIVIVA reduced seasonal water use by 27% and drainage loss by 45%, on average, with respect the timer control system, without showing significant effects of plant growth.