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| Effects of combined application of coated ureas and ordinary ureas on ammonia volatilization in paddy fields |
| Received:August 22, 2021 |
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| KeyWord:controlled-release blended fertilizer;polyurethane-coated urea;ammonia volatilization;paddy field;nitrogen use efficiency |
| Author Name | Affiliation | E-mail | | KANG Xingrong | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | ZHOU Xuan | Hunan Soil and Fertilizer Institute, Changsha 410125, China | zhouxuan_123@126.com | | PENG Jianwei | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | 314967900@qq.com | | YANG Xiangdong | Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China | | | XU Zhangqian | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | HUANG Yuelin | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | | | FEI Jiangchi | College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China | |
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| Abstract: |
| To effectively reduce the loss of N and improve the N fertilizer use rate in the double-cropping rice areas of plain river networks, this study used one-time fertilization with polyurethane-coated and common ureas to explore the effects of the controlled release fertilizer on ammonia volatilization loss and N use efficiency in the early rice season. We conducted a field experiment for two consecutive years, 2018 to 2019, in Yiyang, Hunan Province, China. We set four treatments：no N fertilizer（CK）, conventional fertilization（CF）, polyurethane-coated urea（PuCU）, and a 6∶4 ratio of polyurethane-coated urea to common urea（0.6PuCU + 0.4CF）. We monitored the characteristics of ammonia volatilization during rice growth using semi closed ventilation. The results showed that ammonia volatilization mainly occurred within 10 days after fertilization under the CF and 0.6PuCU + 0.4CF treatments, and the peak values occurred on the second to third and tenth days, respectively. However, the ammonia volatilization flux of the PuCU treatment was slow during the entire early rice-growing season, being slightly higher than that of the CK treatment. We observed the maximum ammonia volatilization loss（rate） of 39.48 kg·hm-2（22.22%）in the CF treatment, and the N recovery efficiency（NRE）and N agronomic efficiency（NAE）were 29.19% and 13.82 kg·kg-1, respectively. The total ammonia volatilization loss（rate）of the PuCU and 0.6PuCU+0.4CF treatments were 12.01 kg·hm-2 （3.91%）and 20.70 kg·hm-2（9.70%）, respectively; the NRE were 60.22% and 71.36%, respectively; and the NAE were 18.99 kg·kg-1 and 20.34 kg·kg-1, respectively. Compared with that in the CF treatment, the total ammonia volatilization loss in the 0.6PuCU+0.4CF and PuCU treatments were lower by 47.57% and 69.56%, respectively, whereas NRE increased by 163.08% and 116.29% and NAE by 69.85% and 55.97%, respectively. The Elovich equation fit the variation trend of ammonia volatilization accumulation in rice fields with time, and the correlation coefficients of each treatment were extremely significant. From the results of correlation analysis, we found a significant positive correlation between ammonia volatilization flux and pH and the concentrations of NH4+-N in surface water during the early rice season. Overall, we found that a one-time base application of polyurethane-coated urea can effectively avoid the sharp rise in NH4+-N, reduce ammonia volatilization loss from paddy fields, and improve the N use efficiency of early rice. Moreover, combining these two ureas in proportion to each other can further promote N absorption and improve the N use rate, but their combined use has a weaker effect on ammonia volatilization reduction compared with the use of polyurethane-coated urea alone. |
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