| 长期施肥对土壤氮矿化的影响 |
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| 作者姓名： | YAN De-Zhi WANG De-Jian SUN Rui-Juan LIN Jing-Hui |
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| 作者单位： | [1]College of Material and Environmental Science, Qingdao University of Science and Technology, Qingdao 266042（China）. [2]Institute of Agricultural Remote Sensing＆Information System Application, Zhejiang University, Hangzhou 310029（China） [3]Department of Agriculture and Rural Development for Northern Ireland, Agricultural and Environmental Science Division, gewforge Lane, Belfast BT9 5PX （UK） |
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| 摘 要： | Two field experiments were conducted in Jiashan and Yuhang towns of Zhejiang Province, China, to study the feasibility of predicting N status of rice using canopy spectral reflectance. The canopy spectral reflectance of rice grown with different levels of N inputs was determined at several important growth stages. Statistical analyses showed that as a result of the different levels of N supply, there were significant differences in the N concentrations of canopy leaves at different growth stages. Since spectral reflectance measurements showed that the N status of rice was related to reflectance in the visible and NIR （near-infrared） ranges, observations for rice in 1 nm bandwidths were then converted to bandwidths in the visible and NIR spectral regions with IKONOS （space imaging） bandwidths and vegetation indices being used to predict the N status of rice. The results indicated that canopy reflectance measurements converted to ratio vegetation index （RVI） and normalized difference vegetation index （NDVI） for simulated IKONOS bands provided a better prediction of rice N status than the reflectance measurements in the simulated IKONOS bands themselves. The precision of the developed regression models using RVI and NDVI proved to be very high with R2 ranging from 0.82 to 0.94, and when validated with experimental data from a different site, the results were satisfactory with R2 ranging from 0.55 to 0.70. Thus, the results showed that theoretically it should be possible to monitor N status using remotely sensed data.
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| 关 键 词： | 水稻 多谱线 光谱反射 氮 |
| 收稿时间： | 2005-05-03 |
| 修稿时间： | 2005-12-20 |
N mineralization as affected by long-term N fertilization and its relationship with crop N uptake |
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| YAN De-Zhi,WANG De-Jian,SUN Rui-Juan,LIN Jing-Hui.N mineralization as affected by long-term N fertilization and its relationship with crop N uptake[J].Pedosphere,2006,16(1):125-130. |
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| Authors: | YAN De-Zhi WANG De-Jian SUN Rui-Juan and LIN Jing-Hui |
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| Institution: | Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: dzyan@issas.ac.cn;Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China);Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: dzyan@issas.ac.cn;Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: dzyan@issas.ac.cn;Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: dzyan@issas.ac.cn |
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| Abstract: | A field experiment established in 1997 was conducted to study the effect of long-term N fertilizer application on N mineralization in a paddy soil determined using a laboratory anaerobic incubation followed with a field incubation and to measure the relationship between in situ N mineralization and crop N uptake. To estimate N mineralization in the laboratory, soil samples were collected from plots with N application at different rates for six years and were incubated. Soils treated with fertilizer N mineralized more N than unfertilized soils and mineralization increased with N application rates. Also, the fraction of total N mineralized increased with increasing N fertilizer application. These findings meant that a substantial portion of previously applied N could be recovered slowly over time in subsequent crops. The field incubation of the plot receiving no fertilizer N showed that the NH4+-N concentration varied greatly during the rice-growing season and seasonal changes of N mineralization were due more to accumulation of NH4+-N than NO3--N. Rice N uptake increased up to a maximum of 82 kg N ha-1 during the season. The close agreement found between in situ N mineralization and rice N uptake suggested that the measurement of in situ N mineralization could provide useful recommendations for adequate fertilizer N application. |
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| Keywords: | canopy spectral reflectance multispectral data nitrogen status rice vegetation indices |
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