Chinese Journal of Agrometeorology ›› 2017, Vol. 38 ›› Issue (03): 163-171.doi: 10.3969/j.issn.1000-6362.2017.03.004

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Effects of Biochar Application on the Losses of Nitrogen and Phosphorus in Surface Water of Paddy Field

XIAO Jian-nan, ZHANG Ai-ping, LIU Ru-liang, YANG Zheng-li   

  1. 1.Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences /Key Laboratory of Agricultural Environment, Ministry of Agriculture, Beijing 100081, China; 2.Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan 750000
  • Received:2016-08-08 Online:2017-03-20 Published:2017-03-13

Abstract: Applied high rates of nitrogen (N) fertilizer in rice production may result in lower N use efficiency in a paddy rice field of the Yellow River irrigation region, Ningxia. To reduce N and phosphorus (P) leaching and improve fertilizer use efficiency are important for sustainable and water quality. Thus, a field plot experiment was conducted to study the effect of exogenous biochar application on the loss risk of N and P and soil quality in a paddy field. Four biochar rates, i.e., 0, 4500, 9000, and 13500kg·ha-1 with optimum nitrogen rate (240kg·ha-1) were chosen. From May to October 2014, we determined the contents of NH4+-N, NO3--N, total N (TN) and total P (TP) in the surface water of paddy field during the whole rice growth period. The results showed that biochar amendment decreased the contents of both TN and NO3--N but increased NH4+-N content in the surface water. The contents of TN and NH4+-N reached the peak on the following day of the first top dressing and the maximum values were 34.86 and 8.28mg·L-1 respectively. The content of NO3--N reached the peak on the following day of the second top dressing and the maximum value was 3.31mg·L-1. Then TN leveled off after 10 days, but the NH4+-N and NO3--N contents approached a relatively stable level after a week. There was no significant difference in TP content in the surface water between the biochar addition and the control treatments. The content of TP peaked 3 days after fertilization and decreased rapidly afterwards, then leveled off after another 6-7 days. On the other hand, biochar amendment decreased TN leaching by 8.03%-13.36% relative to control, but the high-level biochar amendments (13500kg·ha-1) significantly (P<0.05) increased the contents of TN and soil organic matter by 41.2% and 27.5% respectively compared with the control. There was no significant difference in TP and available P contents in soil between the biochar addition treatments and the control. Our study has revealed that biochar could positively reduce N leaching in the rice fields, while there has no significant effect on P loss.

Key words: Biochar, Surface water of paddy field, Nitrogen, Phosphorus, Soil nutrients