酚酸对连作杨树人工林土壤硝化作用的影响

发布时间：2018-09-18 20:21

【摘要】：本研究以化感效应为切入点,以山东省宁阳县高桥林场连作杨树人工林为研究对象,采用田间施肥与室内培养相结合的方法,对施加15N标记的铵态氮肥后杨树人工林土壤硝化作用中氮素的迁移与转化进行定量研究,以阐明杨树人工林土壤氮素有效性的变化规律,揭示酚酸类化感物质对连作杨树人工林土壤氮素循环的中心环节——硝化作用的影响机制,以期进一步完善人工林连作障碍产生机制的理论体系。1野外定位连作杨树人工林试验林的研究结果表明:(1)杨树人工林土壤中酚酸总量呈现II代根际I代根际II代非根际I代非根际。(2)在同一林地的根际土和非根际土中,根际土壤中铵态氮和硝态氮的变化速率及硝化活性均显著大于非根际土;与氮素损失有关的羟胺还原酶和亚硝酸还原酶在根际与非根际土中没有显著差异,而硝酸还原酶活性在根际与非根际土壤中呈显著差异。(3)在不同林分中,铵态氮和硝态氮的含量及其变化速率、土壤硝化活性的变化均表明连作人工林土壤酚酸的累积导致土壤中铵态氮向硝态氮转化的微生物活性下降,转化速率减小,导致转化量减少,杨树人工林连作对土壤硝化作用产生了抑制性。同时,在硝化过程中,连作对羟胺还原酶、硝酸还原酶和亚硝酸还原酶的活性几乎没有影响,对氮损失也几乎没有影响,但是有加速氮损失的趋势。2向杨树人工林I代林非根际土添加梯度外源酚酸的室内研究结果表明:随着酚酸浓度的增加,硝态氮的累积渐近值和铵态氮的消耗渐近值逐渐减小,硝化微生物的硝化活性逐渐降低,对硝化作用产生抑制。同时随着酚酸浓度的提高,土壤中硝酸还原酶的活性加强,使土壤中的N素损失量增大。3通过对连作杨树人工林和梯度酚酸作用下硝化进程研究,可以得出这样的结论:酚酸一方面通过抑制硝化微生物的活性,影响铵态氮向硝态氮的转化,抑制硝化作用的进行;另一方面促进了与反硝化作用有关的硝酸还原酶活性,使氮素的气态损失增加,土壤中氮素“库”源含量下降,使杨树可吸收利用的氮素减少,林分生产力下降。
[Abstract]:In this study, allelopathy effect was taken as the starting point, and continuous poplar plantation in Gaoqiao Forest Farm, Ningyang County, Shandong Province was used as the research object. The method of combining field fertilization with indoor cultivation was adopted. The transfer and transformation of nitrogen in soil nitrification of poplar plantation were studied quantitatively after applying 15N-labeled ammonium nitrogen fertilizer, in order to elucidate the change rule of soil nitrogen availability in poplar plantation. The effects of phenolic acid allelopathy on nitrification in soil nitrogen cycle of continuous cropping poplar plantation were revealed. In order to further improve the mechanism of continuous cropping obstacle in artificial forest. 1. The results of field study on continuous cropping poplar plantation showed that: (1) the total amount of phenolic acid in soil of poplar plantation showed II generation I rhizosphere II generation. Non-rhizosphere I generation non-rhizosphere. (2) in the rhizosphere soil and non-rhizosphere soil of the same forest land, The rate of change and nitrification activity of ammonium and nitrate in rhizosphere soil were significantly higher than those in non-rhizosphere soil, but there was no significant difference between rhizosphere and non-rhizosphere soil of hydroxylamine reductase and nitrite reductase related to nitrogen loss. However, nitrate reductase activity was significantly different in rhizosphere and non-rhizosphere soil. (3) the content and change rate of ammonium and nitrate in different stands. The change of soil nitrification activity indicated that the accumulation of phenolic acid in soil of continuous cropping plantation resulted in the decrease of microbial activity in the transformation of ammonium nitrogen to nitrate nitrogen, the decrease of transformation rate, and the decrease of transformation amount. Continuous cropping of poplar plantation inhibited soil nitrification. At the same time, during nitrification, the activities of hydroxylamine reductase, nitrate reductase and nitrite reductase were almost not affected by continuous cropping, and the loss of nitrogen was hardly affected. But there was a tendency of accelerating nitrogen loss. 2. The results of laboratory study on adding gradient exogenous phenolic acid to non-rhizosphere soil of poplar plantation indicated that the cumulative asymptotic value of nitrate nitrogen and the asymptotic value of consumption of ammonium nitrogen gradually decreased with the increase of phenolic acid concentration. The nitrification activity of nitrifying microorganism decreased gradually and inhibited nitrification. At the same time, with the increase of phenolic acid concentration, the activity of nitrate reductase in soil was strengthened, and the amount of N loss in soil increased by 3. 3. The nitrification process under the action of continuous cropping poplar plantation and gradient phenolic acid was studied. It can be concluded that phenolic acid, on the one hand, inhibits nitrification by inhibiting the activity of nitrifying microorganisms, and inhibits nitrification, on the other hand, promotes nitrate reductase activity related to denitrification. The gas loss of nitrogen was increased, the nitrogen "sink" content in soil decreased, the nitrogen uptake and utilization of poplar decreased, and the stand productivity decreased.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S792.11;S714.2

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