Abstract
To face climatic changes, the increase of frequency and severity of droughts, and economic development pressures, Water Management Institutions point at the necessity of water conserving. A sustainable demand-led approach is the most viable option, focusing on achieving more efficient irrigation practices instead of less sustainable expansion of supply. The aim of this work is to investigate on some aspects of the rational water management for the irrigation of corn in order to evaluate the actual possibility of introduction of drip irrigation systems on the Venetian Plain. Trials were carried out on a farm located in Isola della Scala (Verona, Italy) in an area of about 13 ha (12 ha with a drip irrigation system and 1 ha with a solid-set sprinkler system); the effects of the performance of the two systems on waxy corn yield were considered. In particular, water distribution uniformity, water use efficiency, and yield performance of irrigation systems were evaluated. DUlq and CU coefficients for distribution uniformity and IWUe and WUEb indexes for water use efficiency were calculated. To visualize and better analyze the distribution uniformity, the crop yield and the efficiency parameters, ArcGIS 10 (ESRI?) with IDW interpolation were used to create maps. First results show a good water uniformity distribution in the drip irrigation system but only with a careful and proper design of the entire system. As regards the water use efficiency, drip irrigation values are lower than those of sprinkler irrigation (-46% for IWUe and -25% for WUEb), probably due to different irrigation management and water volumes used: in fact, drip irrigation was scheduled every three days, while only supplemental operations were done for sprinkler irrigation. No statistical correlation was found between application rate and yield for both irrigations systems, while a significant correlation was found between irrigation volume and crop water use efficiency. The profitability of the two irrigation systems was compared. The results show that the income of drip irrigation is slightly lower than sprinkler irrigation, mostly due to the use of “throw away” drip lines.
Highlights
In 2050 an increase in water consumption up to 11% and a duplication in food production needs have been predicted [1]
Comparing the two irrigation methods it can be noted that the average yield of the drip irrigation system was higher by only 8.6% in regard to sprinkler system, even if the seasonal irrigation volume distributed was more than 50%
The trials carried out during summer 2012 have shown how the drip irrigation system allows for a good distribution uniformity, but careful designing is necessary in order to reduce the head loss into the drip lines
Summary
In 2050 an increase in water consumption up to 11% and a duplication in food production needs have been predicted [1]. For this reason the correct choice of irrigation method along with a rational irrigation water management will be essential to increase the water use efficiency. A reduction in water losses and a utilization of low irrigation volume are needed, integrating the irrigation practice into a sustainable cultivation with a rational water use [2] [3]. The distribution uniformity is a parameter to indicate the irrigation system capability to apply the same application rate to a surface unit for the surface and sprinkler methods, or to discharge the same water volume from each emitter for the microirrigation methods. With a scarce distribution uniformity some zones will be over-watered and other ones will be under-watered [4]-[6]
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