膨润土-腐植酸与氮肥配施对科尔沁沙地土壤无机氮淋溶和生物有效性的影响

The effects of bentonite-humic acid amendment and nitrogen application on soil inorganic nitrogen leaching and bioavailability in Horqin sandy soil

利用改进提取方法(温度由25℃升至60℃,振荡时间由1 h提高至2 h)和离子交换膜法,设置3种改良剂水平和3种氮肥水平,研究了膨润土-腐植酸改良剂与氮肥配施对西辽河平原沙质土壤氮素淋溶和养分有效性的影响。结果表明,不施氮肥只施膨润土-腐植酸改良剂对春玉米产量和土壤无机氮残留量无显著影响。20t·hm^-2膨润土-腐植酸改良剂与120 kg·hm^-2氮肥配施效果最好,玉米籽粒产量和地上生物量分别提高了19.1%和18.5%,土壤NO3^--N残留量减少14.5%;施用240 kg·hm^-2氮肥不仅对玉米产量无显著影响,还增加了氮素淋溶的风险。在同一处理下,与标准提取方法相比,改进方法对土壤NH4+-N含量影响较小,还提高了土壤NO3--N提取量。施用膨润土-腐植酸改良剂可吸附滞留在土壤中的NO3^--N,这不仅降低淋溶风险,同时也降低生物有效性。20 t·hm^-2膨润土-腐植酸改良剂与120 kg·hm^-2氮肥配施是一种既能提高土壤氮素有效性又能减少氮素淋溶的最佳组合。

By using the modified extraction method(temperature was increased from 25℃ to 60℃,oscillation was extended from 1 h to 2 h)and cation-exchange membrane method,three soil amendment application rates and three nitrogen dose combinations were set up to study their effects on sandy soil nitrogen leaching and bioavailability by combining addition of the bentonite-humic acid amendment and nitrogen in west Liaohe river plain.The results showed that,only addition of bentonite-humic acid amendment had no significant effect on maize yield and soil residual inorganic nitrogen.The combination of 20 t·hm^-2 bentonite-humic acid amendment and 120 kg·hm^-2 nitrogen showed the best improvement on maize grain yield,above-ground biomass yield and soil NO3^--N residual,with an increase by 19.1% and 18.5% on maize grain yield and above-ground biomass yield,14.5% decrease on soil NO3^--N residual,respectively.However,addition of 240 kg·hm^-2 of nitrogen had no significant influence on maize yield,but raised the risk of nitrogen leaching.Under the same treatment,modified method showed little influence on soil NH4+-N content,but increased soil NO3--N content compared with standard method. Bentonite-humic acid amendment absorbed the NO3--N in the soil,it not only reduced the risk of nitrogen leaching,but also decreased soil bioavailability. It indicated that the combination of 20 t·hm^-2 of bentonitehumic acid amendment and 120 kg·hm^-2 of nitrogen is the best combination for increasing nitrogen availability and reducing nitrogen leaching.