SIMULATION OF NITROGEN DYNAMICS UNDER FILM-HOLE IRRIGATED MAIZE IN NORTHWEST CHINA.

Water and nitrogen (N) are two of the most important inputs for high maize yields. An experiment was carried out in random group design to study the effects of irrigation amount and frequency on NO₃^--N distribution and crop water use efficiency in maize field under film-hole irrigation in 2012 and 2013 and compare and analyze water consumption between film-hole and border irrigation. There were three irrigation amount treatments, which were 37.48mm, 52.47mm and 67.47mm, and three irrigation frequency, which were 3,4,5 frequencies during the planting period under film-hole irrigation. In addition, there was also a border irrigation treatment with 67.47mm and 5 irrigation frequencies as control group. The research results showed that, NO₃^--N concentration in 80-100cm soil layers increased with irrigation water increase especially in maize jointing and heading stage under the same irrigation frequency. And NO₃^--N concentration peak of 5 irrigation frequencies appeared at 50cm soil layers, however, that of 3 and 4 irrigation frequencies appeared at 40cm soil layers. Moreover, film-hole irrigation can transform soil ineffective evaporation into effective crops transpiration and improve crop production efficiency as compared with border irrigation. To summarize, taking maize yield, crop water use efficiency and economic benefit of water using into consideration, one-time irrigation amount of 52.47mm and 4 irrigation frequencies are recommended to be used in film-hole irrigation. [ABSTRACT FROM AUTHOR]