Journal of Ecology and Rural Environment ›› 2018, Vol. 34 ›› Issue (8): 755-761.doi: 10.11934/j.issn.1673-4831.2018.08.012

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Effects of Hydrochar and Pyrochar on Rice Yield and Nitrogen Use Efficiency

WANG Yue-man1,2, FENG Yan-fang2, YANG Lin-zhang1,2, LIU Yang2, HOU Peng-fu2, LI Hui-xin1, XUE Li-hong1,2   

  1. 1. College of Resources and Environment Science, Nanjing Agricultural University, Nanjing 210095, China;
    2. Institute of Resources and Environment, Jiangsu Academy of Agriculture Sciences/Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, Ministry of Agriculture, Nanjing 210014, China
  • Received:2017-12-20 Online:2018-08-25 Published:2018-08-23

Abstract:

Biochar has received extensive attention as soil amendment, solid carbon sequestration and pollution reduction method in recent years. Hydrothermal carbonization (HTC) of biomass to produce hydrothermal carbon, i. e., hydrochar, has attracted great interest in the past few years. Hydrochar produced with HTC process exhibited many advantages over pyrochar, such as lower side-effects during production, less energy consumption as well as higher yield and better application prospect as precursor. However, there were limited studies on the application of hydrochar to farmland, and up to now, few reports are related to the application of hydrochar to rice paddy field. Herein, soil column experiment was conducted and hyrochar was for the first time applied to rice paddy field. As comparison, biochar prepared under high temperature pyrolysis conditions (pyrochar, PSBC) and hydrothermal carbonized conditions (hydrochar, HSBC) of sawdust were applied with two application rates (w=0.5%, w=3%, respectively). And their influences on rice growth, yield and nitrogen use efficiency (NUE) were evaluated. Results show that PSBC-0.5% and HSBC-0.5% were observed no significant effect on rice yield (P>0.05). PSBC-3% had no prominent influence on rice yield and growth, surprisingly, HSBC-3% induced a significant reduction (P<0.05) by 64.73% in rice yield, mainly resulted from the reduction of grains per spike and seed setting rate. Additionally, nitrogen uptake of grain, NUE and agronomic efficiency of PSBC-0.5% treatment increased by 23.68%, 57.46% and 1.86% compared with CKU, respectively. In contrast, the treatment of HSBC-3% significantly inhibited rice growth, which reduced nitrogen uptake of grain by 67.46% compared with CKU, and the utilization efficiency and agronomy efficiency of nitrogen fertilizer were negative. Results show that HSBC with high application rate had a significant negative impact on rice growth, while this phenomenon was not observed in low application rate of HSBC. Therefore, to prevent the adverse effects on agricultural production, hydrochar application rate should be controlled strictly or some engineering pretreatment measures are recommended to improve their biocompatibility.

Key words: hydrothermal carbonation, pyrolysis, application rate, rice yield, nitrogen use efficiency

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