Pedosphere 32(6): 856--865, 2022
ISSN 1002-0160/CN 32-1315/P
©2022 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Nitrogen slow-release behavior of oxamide granules in two different types of paddy soils
Xun LI1, Jinlong DONG1, Jingjing DUAN2, Wenzhong SHEN3, Zengqiang DUAN1
1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008(China)
2School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013(China)
3Agricultural Technology Promotion Center, Taicang Agriculture Committee, Suzhou 215400(China)
ABSTRACT
      Oxamide is a potential slow-release nitrogen (N) fertilizer, especially under waterlogged conditions, due to its low solubility in water and the slow-release of ammonium by soil amidases. To investigate the effects of oxamide granules (2.00-2.38 mm in diameter) as a single basal fertilizer (180 or 144 kg N ha-1) on rice growth, soil properties, and N use efficiency in terms of N recovery efficiency (NRE), we conducted field experiments on two different types of paddy soils over two rice-growing seasons. Results showed that the fertilization effects of oxamide granules varied between the two types of paddy soils. In the red clayey paddy soil, the grain yields for both rice-growing seasons were high with a significantly higher NRE in the oxamide treatment than in the urea treatment. However, in the alluvial sandy paddy soil, the grain yields in the oxamide treatment were slightly lower than those in the urea treatment. Furthermore, oxamide produced little improvement in NRE in the alluvial sandy paddy soil. Soil incubation experiments over 98 d were also carried out to evaluate the factors affecting the N release behavior of oxamide granules in the two types of paddy soils. We found that the amidase activity was higher and, therefore, the oxamide hydrolysis rate was faster in the alluvial sandy paddy soil, which had a higher soil pH value and organic matter content, compared to the red clayey paddy soil. The faster N release and the longer growth period resulted in a mismatch between N supply by oxamide and rice demand, which, in turn, led to little improvement in NRE and a decreased grain yield in the alluvial sandy paddy soil, especially in the reduced oxamide treatment. These results could help select the appropriate size of oxamide granules for use as a slow-release N fertilizer depending on the soil properties and growth period of rice.
Key Words:  amidase activity,grain yield,nitrogen use efficiency,organic matter content,pH,slow-release fertilizer
Citation: Li X, Dong J L, Duan J J, Shen W Z, Duan Z Q. 2022. Nitrogen slow-release behavior of oxamide granules in two different types of paddy soils. Pedosphere. 32(6): 856-865.
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