Abstract:In order to reveal the absorption and utilization of topdressing to maize under different irrigation schemes, 15N tracer technology was used based on field test data, the ratio of absorption and utilization to topdressing was analyzed and the distribution of fertilizer nitrogen in the upper parts of maize under different irrigation schemes, and the residue in the soil and final loss rate of nitrogen after harvest were studied. The results showed that 8.14%~13.21% of total nitrogen accumulation in maize aboveground parts came from topdressing under different irrigation schemes, there was a significant difference between the treatments (P<0.05). Among them, topdressing nitrogen accumulation in the grain accounted for 47.90%~74.40% of the total topdressing accumulation. The nitrogen recovery rate of top dressing was 19.16%~64.72% under different treatments, and the recovery rate of grain topdressing was 11.29%~47.17%. The proportion of topdressing nitrogen in different organs was different, the distribution of 47.95%~74.40% was in grain, 10.50%~27.73% was in leaves, 3.02%~9.48% was in stem, 5.22%~15.53% was in spike axis, and only 0.53%~2.35% was in coating. In the early stage of maize growth, the irrigation amount was too large and the water shortage in the later period would have a negative effect on the absorption of nitrogen in the plant and the redistribution of nitrogen to the grain. At the same time, the amount of single irrigation was too large, resulting in the leaching loss of nitrogen, waste of resources and pollution of environment. After harvest, there were 8.81%~24.89% topdressing nitrogen residue in the soil. With the decrease of irrigation frequency and increase of single irrigation amount, the nitrogen residue rate of topdressing was decreased gradually. Considering yield and fertilizer utilization ratio, the irrigation scheme which met the requirements of water saving, high yield and high efficiency in this area was 800m3/hm2 of irrigation quota and four times of irrigation (seedling, jointing, tasselling and filling), the results can provide theoretical support and data reference for maize production in Northeast China.
