不同改良剂对珊瑚砂理化性质和氮素固持的影响

Effects of Different Amendments on Physicochemical Properties and Nitrogen Fixation in Coral Sands

摘要:

高碱环境和土壤养分的匮乏严重限制了我国热带珊瑚岛土壤环境下植物的生长适应能力，因此，珊瑚砂改良对促进珊瑚岛植被恢复，维持珊瑚岛生态环境可持续健康发展具有重要意义。该研究通过室内土柱模拟试验，对比了同一梯度下4种常用土壤改良材料(蛭石、珍珠岩、生物炭和钙基膨润土)对珊瑚砂理化性质、氮素淋溶以及总氮含量的影响。结果表明, 与对照(CK)相比，施用生物炭使珊瑚砂pH显著降低1.4%，钙基膨润土、生物炭和蛭石能够显著提高珊瑚砂的阳离子交换量至CK的24.21、10.43和9.43倍。同时，施用生物炭、钙基膨润土和蛭石并不能降低以硝态氮形式为主的氮素淋失, 但是能显著减少其他途径的氮素损失，从而达到促进珊瑚砂氮素固持的效果，3种改良剂施用下的珊瑚砂总氮损失相较于CK分别降低了40.92%、27.32%和25.09%。因此，施用生物炭、钙基膨润土和蛭石均能有效提高珊瑚砂土壤质量，对改良珊瑚砂和热带珊瑚岛植被恢复具有重要意义，其中生物炭的改良效果最为显著，是改良珊瑚砂的理想材料。

Abstract:

The adaptability of plant growth in soil conditions on Chinese tropical coral islands is severely limited by the alkaline environment and soil nutrient deficiencies. Improving coral sand is essential to facilitate the rejuvenation of coral island vegetation and maintain the healthy development of the coral island ecosystem. In this study, we investigated the effects of four common soil amendment materials (vermiculite, perlite, biochar and calcium-based bentonite) on the physicochemical properties, nitrogen leaching and total nitrogen content of coral sand under the same gradient using an indoor soil column simulation test. The results showed that the application of biochar significantly reduced the pH of coral sand by 1.4% compared to the control (CK), and calcium-based bentonite, biochar, and vermiculite were able to significantly increase the cation exchange capacity of coral sand to 24.21, 10.43, and 9.43 times that of CK. Meanwhile, during the leaching process, nitrogen was rapidly leached out mainly in the form of nitrate nitrogen, and the application of biochar, calcium-based bentonite and vermiculite could not reduce the nitrogen leaching loss, but it could achieve the effect of promoting nitrogen fixation in coral sands by promoting nitrogen fixation through other pathways, which resulted in the reduction of total soil nitrogen loss under the addition of the three amendments versus CK by 40.92%, 27.32% and 25.09%, respectively. The utilization of biochar, vermiculite and calcium-based bentonite can therefore effectively improve the quality of coral sand soil, which is of great significance for the improvement of coral sand and the restoration of tropical coral island vegetation, among which biochar has the most significant improvement effect and is the ideal material for the improvement of coral sand.