THE INFLUENCE OF DIFFERENT DRIP IRRIGATION LAYOUT DESIGNS ON SUGAR BEET YIELD AND THEIR CONTRIBUTION TO ENVIRONMENTAL SUSTAINABILITY

Abstract

Drip irrigation may constitute a method for sustainable management of water resources and can contribute to environmental protection and sustainability. However, there is still limited information on the application of drip irrigation to row field crops in Mediterranean environments, especially with respect to its appropriate lateral layout, a parameter that affects initial system installation cost as well as water use efficiency. Surface drip irrigation (SDI) field experiments with sugar beets (Beta vulgaris L.) were conducted in central Greece over a 3-year period to determine the effects of different layout designs (4 treatments with 6 replications) on root yield, sucrose accumulation characteristics (percent sugar content of roots (POL), raw sugar yield), water productivity index (WPI), and to study the contribution of different layout designs to environmental protection and sustainability. The treatments used consist of combinations of drip-pipes with varying lateral distances of every-other-furrow (e-o-f) (1.00 m) and every-three-furrows (e-t-f) (1.50 m), and between the dripper spacing (0.50 m and 0.75 m). The mean root yield results in the e-o-f treatments were 108.46, 111.46 and 105.11 t.ha(-1), and in the e-t-f treatments were 106.17, 113.59 and 103.84 t-ha(-1) for each year, respectively. The root sugar contents varied from 11.68% to 13.00% in e-o-f and from 11.46% to 13.41% in e-t-f. The WPI results were 19.74, 19.44 and 17.97 kg-m(-3) in e-of, and 19.32, 19.81 and 17.75 kg.m(-3) in e-t-f, respectively. Differences in root yield, POL, raw sugar yield and WPI between the 3 harvest periods were not statistically significant (p<0.05). Therefore, in agricultural Mediterranean areas with aquic soil moisture regimes, the suggested layout design of e-t-f (1.5 m x 0.75 m) instead of the common farmers' layout of e-o-f (1.0 m x 0.50 m) can be applied without statistically significant differences in root yield, POL, raw sugar yield or WPI, and with considerable plastic material reduction (-33.3% polyethylene), which corresponds to an initial cost reduction of -37.2%. Moreover, using this method, important installation labour savings, as well as cost reductions for transportation and storage facilities, are realized.