苏打盐碱地稻田氨挥发及氮素利用效率研究

发布时间：2018-11-25 13:32

【摘要】：苏打盐碱地稻田氮素含量水平低、土壤保肥性能差,土壤盐碱化程度和施氮水平对水稻产量和氮素利用效率影响很大,氮素利用效率一直难以提高。本文利用稳定性15N同位素标记尿素研究了盐碱地稻田氮素的吸收利用规律,研究了盐碱地稻田氨挥发及其影响因素,不同施肥处理下的水稻根系活力、产量及产量性状的变化,以及盐碱地稻田的氮素利用效率。主要研究结果如下:1.模拟试验研究发现,在pH 8.55到pH 9.58之间,三种氮肥氨挥发的大小顺序是:硫酸铵硝酸铵尿素,尿素氨挥发随着EC的增加而增大。尿素在pH7.59-8.55之间,氨挥发量随着pH的升高而增大,且pH 8.55时量达到最大值。2.盆栽试验研究发现,中度盐碱土上的氨挥发量显著大于轻度盐碱土上的氨挥发量;氨挥发量与施氮量呈显著正相关。基于长期定位施肥试验发现,NPK肥配施有机肥以及NPK肥配施秸秆可减少氨挥发损失。3.基于田间试验发现,土壤盐碱化显著抑制了水稻的营养生长和生殖生长。随着土壤pH的升高,水稻结实率降低。当土壤pH达到9.0以上,水稻结实率降到40%左右。土壤盐碱胁迫对水稻地上部的生长影响显著。在相同盐碱程度下,合理施用氮肥可显著促进水稻生长,增加稻谷产量,减缓盐碱化对水稻生长的抑制作用。4.水稻根系伤流液的出液速率随着施氮水平的提高显著提高,表明提高施氮水平有利于增强水稻根系活力。且抽穗期伤流液出液量越大,稻谷产量越高。5.在相同的盐碱程度下,不同耐盐碱品种水稻对氮肥的需求存在差异。东稻4号、东稻2号和白粳1号在低氮(150 kg·N/hm2)处理下产量最高;长白9号在高氮(300 kg·N/hm2)处理下稻谷产量最高。因此,在生产上应根据土壤盐碱程度和水稻品种特性合理确定最佳施氮量。6.土壤盐碱化程度显著影响氮素利用效率。施氮量从75 kg·N/hm2增加到300 kg·N/hm2,轻度盐碱土水稻氮素恢复利用效率为46.75%-62.95%;中度盐碱土水稻氮素恢复利用效率为39.84%-48.21%;在上述2种土壤上,土壤15N残留率在4.1%-10.0%之间。7.以土壤氮素平衡作为施用氮肥的依据,通过氮素归还指数法计算盐碱地田块尺度的最佳施氮量,得出盐碱地稻田秸秆还田情况下的氮素归还施氮量计算公式为:RNR=1.267×10~(-6)Y_产~2+1.24×10~(-2)Y_产-41.4;若稻田没有秸秆还田,计算公式为:RNR=1.267×10~(-6)Y_产~2+1.24×10~(-2)Y_产-22.7。
[Abstract]:The level of nitrogen content in paddy field is low, the soil fertility is poor, the soil salinization degree and nitrogen application level have great influence on rice yield and nitrogen use efficiency, but it is difficult to improve the nitrogen use efficiency. In this paper, the absorption and utilization of nitrogen in saline-alkali paddy fields were studied by using stable 15N isotope labeled urea. The ammonia volatilization and its influencing factors in saline-alkali paddy fields were studied, and the changes of root vigor, yield and yield characters of rice under different fertilization treatments were studied. And the nitrogen utilization efficiency of paddy field in saline-alkali soil. The main results are as follows: 1. The simulation results show that between pH 8.55 and pH 9.58, the order of ammonia volatilization of three nitrogen fertilizers is ammonium sulfate urea, and the ammonia volatilization of urea increases with the increase of EC. Between pH7.59-8.55 and urea, ammonia volatilization increased with the increase of pH, and reached the maximum value at pH 8.55. Pot experiment showed that the amount of ammonia volatilization in moderate saline-alkali soil was significantly higher than that in light saline-alkali soil, and there was a significant positive correlation between ammonia volatilization and nitrogen application. Based on the long-term fertilization experiment, it was found that NPK fertilizer combined with organic fertilizer and NPK fertilizer combined with straw fertilizer could reduce ammonia volatilization loss. Based on field experiments, soil salinization significantly inhibited the vegetative and reproductive growth of rice. With the increase of soil pH, the seed setting rate of rice decreased. When soil pH reached above 9.0, the seed setting rate of rice decreased to about 40%. Soil saline-alkali stress had a significant effect on the growth of rice shoot. Under the same salinity, rational application of nitrogen fertilizer could significantly promote rice growth, increase rice yield and slow down the inhibition of salinization on rice growth. 4. The effluents rate of rice root drainage fluid increased significantly with the increase of nitrogen application level, which indicated that the increase of nitrogen application level was beneficial to enhance the root activity of rice. Moreover, the higher the amount of drainage at heading stage, the higher the yield of rice. Under the same saline-alkali degree, the requirement of nitrogen fertilizer in different saline-tolerant rice varieties was different. The yield of Dongdao 4, Dongdao 2 and Baijing 1 was the highest under low nitrogen (150 kg N/hm2) treatment, and Changbai 9 was the highest under high nitrogen (300 kg N/hm2) treatment. Therefore, the optimum nitrogen application rate should be reasonably determined according to the salinization degree of soil and the characteristics of rice varieties in production. 6. 6. Soil salinization significantly affected nitrogen use efficiency. The nitrogen application rate increased from 75 kg N/hm2 to 300 kg N / hm ~ (2), the nitrogen recovery and utilization efficiency of rice in mild saline-alkali soil was 46.75-62.95, that of rice in moderate saline-alkali soil was 39.84 -48.21, and that of rice in moderate saline-alkali soil was 39.84 -48.21. In the above two soils, the residual rate of 15N in soil ranged from 4.1% to 10.0%. The soil nitrogen balance was used as the basis for applying nitrogen fertilizer, and the optimum nitrogen application rate on the scale of saline-alkali land was calculated by the method of nitrogen return index. The formula of nitrogen return amount under the condition of returning rice straw in saline-alkali soil was obtained as follows: RNR=1.267 脳 10 ~ (-6) Y _ yield ~ 21.24 脳 10 ~ (-2) Y _ (-2) Y _ (-41.4); If there is no straw in paddy field, the formula is: RNR=1.267 脳 10 ~ (-6) Y _ yield ~ 21.24 脳 10 ~ (-2) Y _ yield -22.7.
【学位授予单位】：中国科学院大学(中国科学院东北地理与农业生态研究所)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S511

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