Effect of Deficit Irrigation, Air injection and Nitrogen Fertilization on Water Productivity of Carrot under Subsurface Drip Irrigation System.

A field study was conducted in 2017-2018 to evaluate the effect of deficit irrigation, air injection and nitrogen fertilization on yield and water productivity of carrot under subsurface drip irrigation system. Experimental treatments were three levels ofdeficit irrigation (60%, 80% and 100%) of full crop water requirements and three types of nitrogen fertilizer(nitric acid(HNO3)48 % N, urea CO(NH2)2 46% N and ammonium nitrate(NH4NO3)33.5% N, with air injection treatment (12% air by volume of water). The results show that the yield and water productivity as well as the length of carrot root significantly increased for air injection treatments. On the other hand, the carrot diameter increase was not significant. The highest value of the carrot root yield (19.487 ton/fed) was obtained due to deficit irrigation 60% (I60%) and ammonium nitrate(NH4NO3)with air injection. Also, treatment of deficit irrigation (I80%) and urea fertilization CO(NH2)2  with air injection resulted 17.437 (ton/ fed) carrot roots which was significantly higher than that of non-air injection treatments. Also,the highest values of water productivity of carrot were 185.189 and 101.376 kg/m3obtained due to(I60%) with (NH4NO3)and co(NH2)2underair injection treatments, respectively. The highest lengths of carrot (cm) were 19.800 and 19.000 (cm)obtained due to (I80%) with CO(NH2)2and (I100%) with (NH4NO3), under air injection treatments, respectively. The highest values of carrotdiameter were 42.153 and 41.260 (mm) obtained due to treatment of full irrigation(I100%) and(NH4NO3) fertilizer withoutair injection and the treatment (I80%) and CO(NH2)2 fertilizer with air injection, respectively. Data from this study indicate that carrot yield and its water productivity can be improved byaerated sub surface drip irrigation system(SSDI).