Abstract
Single basal application of nitrogen fertilizer using polyolefin coated urea (POCU) on dent corn (Zea Mays L) cultivation was conducted in strongly acid Andisol in 1987-1988. Controlled release nitrogen, POCU (LP 70 or 100 of Chisso-Asahi Fertilizer Co.), was used in dent corn cultivation to save the labpr of topdressing and to maintain the nitrogen nutrition of dent corn in late growing stage. 1) Dry weight and amounts of nitrogen uptake by dent corn at critical level (about 1 m of plant height) were only 1/30 and 1/10 of that at harvesting, respectively. At that critical level, mechanical topdressing was difficult. 2) According to the climatic data of last 21 years, the rainfall more than 1 mm/day which makes difficulties in machine work, appeared every two days around the time of mechanical topdressing. 3) Basal band application of more than 12.5 kg N/10a of amnoniun sulfate inhibited the growth of dent corn significantly, but not that of POCU at least by 40 kg N/10a. 4) Dent corn grown on the plot of single basal application of POCU showed equal or more amounts of nitrogen uptake and yield, and higher lodging resistance to that grown on the conventional plot with topdressing. 5) Amounts of nitrogen released from POCU highly correlated to both cummulative soil temperature and air temperature. 6) Single basal application of POCU are practically useful method for not only labor saving and maintaining the growth of dent corn in late growing stage, but also lowering the impaction of nitrogen fertilyzer to global circumstance.
