草酸和抑制剂对氮肥在喀斯特土壤中迁移规律的影响

Effects of oxalic acid and inhibitors on nitrogen migration rule in Karst soil

【目的】探究草酸、硝化抑制剂(DMPP)和脲酶抑制剂(NBPT)与氮肥配施后氮素在喀斯特土壤中的迁移规律,为喀斯特地区合理施用氮肥及提高肥料利用效率提供科学依据。【方法】采用室内土柱培养法,在土壤湿度为30%条件下,以草酸、DMPP和NBPT与3种氮肥(硝酸钾、氯化铵和尿素)组合配施,培养15、30和90 d后,测定土柱中不同土层的可溶性无机氮含量及其百分率,探究氮肥配施草酸和2种抑制剂对喀斯特土壤中氮素迁移规律的影响。【结果】在15、30和90 d的培养时间下,与单施氮肥相比,氮肥配施草酸和抑制剂对氮素在喀斯特土壤中迁移具有明显影响。硝酸钾、氯化铵和尿素配施草酸后,土壤的可溶性无机氮含量增加,分别为0.516、3.266和0.958 mg/g,同时,3种氮肥在土壤中的可溶性无机氮百分率均升高(硝酸钾、氯化铵和尿素的可溶性无机氮百分率最高分别为16.68%、41.28%和11.02%)。氯化铵配施草酸+DMPP后,土壤的可溶性无机氮含量增加,其百分率提高,且在培养15 d时百分率最高,为45.48%;尿素配施草酸+DMPP后,在培养90 d时土壤的可溶性无机氮含量和百分率均最高,分别为0.935 mg/g和11.19%。【结论】在喀斯特地区土壤中,硝酸钾、氯化铵和尿素分别配施草酸均能提高土壤可溶性无机氮含量,促进氮素向深层次土壤迁移,氯化铵和尿素分别配施草酸+DMPP也可提高土壤可溶性无机氮含量,这些高效利用氮肥的施肥方式可在农业生产上参考应用。

【Objective】The purpose of the study was to explore the migration law of nitrogen fertilizer with oxalic acid,nitrification inhibitor(DMPP)and urease inhibitor(NBPT)in Karst soils.The results would provide a scientific basis for the rational application of nitrogen fertilizer in Karst areas and improve fertilizer utilization rate.【Method】The study employed an indoor soil column culture method with a combi⁃nation of oxalic acid,DMPP,and NBPT,along with three nitrogen fertilizers(potassium nitrate,ammonium chloride,and urea)at 30%soil moisture.After 15,30 and 90 days cultivation,soluble inorganic nitrogen contents were determined in different soil column layers to investigate the effect of the nitrogen transport pattern on nitrogen fertilizer with oxalic acid and two inhibitors in Karst soils.【Result】Nitrogen fertili⁃zation with oxalic acid and inhibitors had obvious effect on nitrogen transport in Karst soils compared to nitrogen fertilization alone at 15,30 and 90 days cultivation times.Potassium nitrate,ammonium chloride,and urea combined with oxalic acid increased soil soluble inorganic nitrogen to 0.516,3.266,and 0.958 mg/g,respectively.The percentage of soil soluble inorganic nitrogen increased in all three nitrogen fertilizers(potassium nitrate,ammonium chloride and urea had the highest percentage of soluble inorganic nitrogen at 16.68%,41.28%and 11.02%respectively).Ammonium chloride with oxalic acid+DMPP increased the soluble inorganic nitrogen content of the soil and its per⁃centage increased.The highest percentage was 45.48%at 15 days of cultivation.Urea combined with oxalic acid+DMPP,resulted in the highest soluble inorganic nitrogen content and percentage in the soil after 90 days of cultivation,which were 0.935 mg/g and 11.19%,respectively.【Conclusion】Potassium nitrate,ammonium chloride and urea,along with oxalic acid,increased the soluble inorganic nitrogen content of the soil and promoted its transport to deeper layers in Karst areas.The content of soluble inorganic nitrogen in the soil increased in the addition of oxalic acid+DMPP to both ammonium chloride and urea.The application of this efficient use of nitrogen fertilizer applica⁃tion method will be employ in the agricultural production.