连续施用炭基肥及生物炭对棕壤有机氮组分的影响

Effects of continuous application of biochar-based fertilizer and biochar on organic nitrogen fractions in brown soil

为了揭示连续施用炭基肥及生物炭条件下棕壤有机氮组分的变化情况,本文基于田间定位试验,研究了连续定位施用炭基肥及生物炭对棕壤有机氮组分的影响。试验共设置5个处理:不施肥、低量生物炭、高量生物炭、氮磷钾配施、炭基肥。于2014年花生收获后每个小区按"S"型设置3个采样点,采集0~20、20~40 cm的土壤样本,利用Branmer有机氮分组方法对土壤有机氮组分进行测定与分析。结果表明:经过连续4年的不同施肥处理,不同处理土壤全氮含量均有所提升;炭基肥处理土壤全氮含量显著高于原始土和CK处理,增幅分别达到69.8%、4.8%;不同施肥处理中有机氮各组分的含量顺序为酸解铵态氮>氨基酸态氮>非酸解氮>酸解未知态氮>氨基糖态氮;施用炭基肥显著增加了土壤酸解有机氮中酸解铵态氮、氨基酸态氮的含量,与原始土相比增加了65.9%、128.0%;随着生物炭用量的增加,酸解铵态氮含量处于增加趋势,但增加幅度远低于等碳投入的炭基肥处理;对于未知态氮、非酸解有机氮总量无论施用生物炭、氮磷钾化肥或炭基肥均提高了其含量,但各处理间差异不显著;连续施用炭基肥或生物炭显著提高了土壤酸解有机氮中酸解铵态氮和氨基酸态氮的含量,促进了氮素的活化,有利于花生中低产田氮素的吸收和运转。

To clarify the change of organic nitrogen fractions with continuous fertilization,a sitespecific plot experiment was used to study the effects of continuous application of biochar-based fertilizer and biochar on the fractions of organic nitrogen in brown soil.Five treatments were employed,including the control without fertilization（CK）;low application level of biochar;high application level of biochar;nitrogen,phosphorus and potassium combined fertilization;and biochar-based fertilizer.Soil samples were collected in 0-20 and 20-40 cm soil layers after the harvest of peanut in 2014.An organic N fractionation method by Brenmer was used to determine soil organic nitrogen fractions.The results showed that after 4 consecutive years of fertilization treatments,total soil nitrogen increased for all the treatments.The total soil nitrogen of biochar-based fertilizer treatment was significantly higher than that in the original soil and CK group,with increases of 69.8% and 4.8% respectively.The contents of soil organic nitrogen fractions in different fertilization treatments were in the order of ammonium N 〉amino acid 〉N non-hydrolysable N 〉hydrolysable unidentified N 〉amino sugar N.The input of biochar-based fertilizer significantly increased the contents of ammonium N and amino acid N in acid hydrolysable organic nitrogen of soil.Compared with the original soil,the input of biochar-based fertilizer increased the contents of ammonium N and amino acid N by 65.9% and 128.0% respectively.As the application rate of biochar increased,ammonium N content showed an increasing trend,but such increment in the biochar treatments was far lower than that in the biochar-based fertilizer treatment.The applications of biochar,NPK fertilizers and biochar-based fertilizer increased the content of hydrolysable unidentified N,and the total content of non-hydrolysable organic nitrogen,but the differences among the treatments were not significant.Overall,continuous application of biocharbased fertilizer or biochar significantly increased the contents of ammonium N and amino acid N from acid hydrolysable organic nitrogen in soil,promoted the activation of nitrogen,and benefited the uptake and transport of nitrogen of low-and middle-yield peanut field.