Pedosphere 14(2): 247--252, 2004
ISSN 1002-0160/CN 32-1315/P
©2004 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Soil NH4+ fixation and fertilizer N recovery as affected by soil moisture and fertilizer application methods |
TONG Yan-An 1, O. EMTERYD2, H. GRIP2 and LU Dian-Qing1 |
1 College of Resource and Environment, Northwest Sci-Tech University of Agriculture and Forestry, State Key Laboratoryof Soil Erosion and Dryland Farming in the Loess Plateau, Yangling, Shaanxi 712100 (China). Email: tongyanan@nwsuaf.edu.cn;
2 Department of Forest Ecology, Swedish University of Agricultural Sciences, Umea S-901 83 (Sweden) |
| ABSTRACT |
| Ammonium fixation and the effects of soil moisture and application methods on fertilizer N recovery were investigated in two soils of Shaanxi Province, China, a Luvisol and an Entisol, through two experiments performed in the laboratory and in a glass shelter, respectively, by using ammonium bicarbonate (NH4HCO3). The laboratory closed incubation box experiment was conducted using the Luvisol to study NH4+ fixation rate at soil moisture levels of 10.1%, 22.7% and 35.3% water filled pore space (WFPS). The fixed NH4+-N increased dramatically to 51% and 66%, 67% and 74%, and 82% and 85% 1, 2 and 36 h after fertilizer incorporation at moisture levels of 10.1% and 22.7% WFPS and 35.3% WFPS, respectively. The rapid NH4+ fixation rates at all moisture levels could help prevent NH4+ losses from ammonia volatilization. In the glass shelter pot experiment, N fertilizer was applied by either banding (in a concentrated strip) or incorporating (thoroughly mixing) with the Entisol and the Luvisol. An average of 74.2% of the added N fertilizer was recovered 26 days after application to the Luvisol, while only 61.4% could be recovered from the Entisol, due to higher NH4+ fixation capacity of the Luvisol. The amount of fixed NH4+ decreased with increasing WFPS. The amount of fixed NH4+ in the incorporated fertilizer treatment was, on average, 10% higher than that in the banded treatment. Higher NH4+ fixation rates could prevent N loss and thus increase N recovery. The results from the Luvisol showed lower nitrogen recovery as soil moisture level increased, which could be explained by the fact that most of the fixed NH4+ was still not released when the soil moisture level was low. When the fertilizer was incorporated into the soil, the recovery of N increased, compared with the banded treatment, by an average of 26.2% in the Luvisol and 11.2% in the Entisol, which implied that when farmers applied fertilizer, it would be best to mix it well with the soil. |
| Key Words: fertilizer application, N recovery, NH4+ fixation, soil moisture |
| Citation: Tong, Y. A., Emteryd, O., Grip, H. and Lu, D. Q. 2004. Soil NH4+ fixation and fertilizer N recovery as affected by soil moisture and fertilizer application methods. Pedosphere. 14(2): 247-252. |
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