生物炭对土壤氮素淋失影响的研究进展

Advances in research on effects of biochar on soil nitrogen leaching

在农业活动中,由于片面追求粮食高产,过度使用氮肥造成土壤养分过剩,由其引发的环境问题日益严峻。生物炭作为一种高效的土壤改良剂,施用后会影响土壤氮素养分的持留,进而影响土壤保氮能力。为明确前人研究成果,为今后开展土壤氮素淋失的研究工作提供借鉴,针对生物炭对土壤氮素淋失的影响展开综述,将外在条件(土壤种类、生物炭类型,使用量及添加方式,作物类型等)和内在条件(生物炭理化性质、微生物作用)相结合,深入探讨并阐明生物炭影响土壤氮素淋失的4种机制:1)生物炭发达的微孔结构及巨大的比表面积赋予其强效的物理吸附性能,可以大大增加土壤中含氮养分的固留时间,从而减少淋溶作用所造成的氮素损失;2)生物炭加入土壤中,改善土壤持水能力,避免氮素养分随水迁移造成损失;3)生物炭提高了土壤CEC值、pH值等,从而增强土体的化学吸附性能;4)生物炭与微生物相互作用,影响土壤中氮素的循环与利用。最后就生物炭应用于土壤氮素控制领域进行了展望。

[Background]In agricultural activities,due to the unilateral pursuit of high food production,the environmental problems from excessive use of nitrogen fertilizer have become increasingly serious.As a highly effective soil amendment,biochar affects the retention of nitrogen nutrients in the soil and affects the nitrogen fixation capacity of the soil.This review aims to clarify the prior research results,and to provide reference for the future research work on soil nitrogen leaching.[Methods]By focusing on the effects of biochar on soil nitrogen fixation capacity,we combined external conditions(soil environment,biochar type,amount and mode of addition,crop type,etc.)and intrinsic conditions(physical properties of biochar,microbial action),and conducted in-depth discussion and clarification of the four mechanisms of biochar′s ability of affecting soil nitrogen fixation,and prospected the future research directions.[Results]1)There are 4 mechanisms of biochar's ability to affect soil nitrogen fixation.a)The microporous structure of biochar and its large specific surface area give it strong physical adsorption properties,which can greatly increase the nitrogen content in soil.The retention time of nutrients reduces the loss of nitrogen caused by leaching.b)Biochar is added to the soil to improve the water-holding capacity of the soil and to avoid the loss of nitrogen nutrients with water migration.c)The oxygen-containing acidic functional groups formed on the surface of the biochar increase the CEC value,pH value,etc.of the soil,thereby enhancing the chemical adsorption performance of the soil.d)The interaction between biochar and microorganisms indirectly affects the circulation and utilization of nitrogen in the soil.2)The future research direction of biochar nitrogen fixation technology and suggestions for the scientific use of biochar in agricultural production are in followings.a)We should actively carry out medium and long-term outdoor tests of biochar,and conduct in-depth research on the stability of biochar.b)We should study the interaction between soil nitrogen nutrients and other nutrients,and verify whether the biochar′s retention of nitrogen nutrients is affected by other nutrient elements.c)We need to consider the environmental problems caused by the biochar production process,which is related to the sustainable development of biochar,which may have certain practical significance.d)Biochar may have a certain upper limit on the ability of nutrient adsorption,and we need to further explore it.e)In agricultural production activities,we should pay attention to the use of biochar,learn to adapt to local conditions,and rationally apply biochar according to different soil conditions to improve the effectiveness of fertilizer nutrient utilization.f)We should try to establish a biochar-soil-crop joint research system to better serve agricultural production.Explore new ways to produce cheaper biochar,and strive to reduce their production costs and maximize their economic benefits.[Conclusions]The relevant works are summarized and 4 mechanisms and 6 prospects are clarified,which may provide the references for the future research on soil nitrogen leaching.