北方典型农田土壤不同团聚体氮素累积及淋溶特征

Nitrogen accumulation and leaching charateristics of different aggregates in typical farmland soils in North China

选取3种北方典型农田土壤——褐土、潮土和黑土为研究对象,采用室内模拟试验的方法,探究不同的氮肥添加次数对土壤团聚体中氮素累积特征以及不同的淋洗次数对氮素淋溶特征的影响,为提高氮肥利用率,减少水土养分流失提供理论基础.结果显示:不同施肥处理中,3种土壤各粒级团聚体中铵态氮和硝态氮含量均随着施肥次数的增加先快速增加然后趋于平稳.其中3种土壤中铵态氮的累积含量从大到小依次为黑土>褐土>潮土,最大累积含量分别为797.34、87.60和44.48 mg/kg;3种土壤中硝态氮累积含量依次为潮土>褐土>黑土,最大累积含量依次为187.99、142.94和141.11 mg/kg;在不同淋洗处理下,各粒级团聚体中氮素含量均随着淋洗次数的增加先快速下降而后趋于平缓.方差分析表明不同施肥和淋洗处理下,3种土壤间氮素含量差异显著(P<0.05).单次施肥后,3种土壤的肥力指标均达到高或者极高水平,且氮素损失主要集中在淋洗前期.本研究揭示了我国北方3种不同类型土壤的氮素累积与淋溶特征,可为北方农田土壤氮肥的合理施用以及减少农田氮素流失提供理论基础.(图4表2参55)

Nitrogen accumulation and leaching effects of typical farmland soils in northern China were systematically studied to understand the nitrogen fertilizer usage.Substantial measures were undertaken to improve the utilization of nitrogen fertilizers and provide a theoretical basis for reducing water and soil nutrient loss.Three types of farmland soils,including drab soil,alluvial soil,and black soil,were used as the research objects.An indoor soil column simulation test was applied to explore the nitrogen accumulation characteristics in soil aggregates with different nitrogen addition and leaching times to assess the effect of nitrogen leaching characteristics.The results revealed that the ammonium nitrogen and nitrate nitrogen content in the aggregates of the three soil types increased rapidly with an increase in the number of fertilizers and then stabilized.Ammonium nitrogen accumulated in the three soils,with the maximum cumulative content observed in the black soil(797.34 mg/kg),followed by the drab soil(87.60 mg/kg),and the minimum content in the alluvial soil(44.48 mg/kg).The cumulative content of nitrate nitrogen in the three soils was as follows:alluvial soil>drab soil>black soil,with maximum cumulative amounts of 187.99,142.94,and 141.11 mg/kg,respectively.Under different leaching times,the nitrogen content in the soil aggregates decreased rapidly initially and then leveled off as the number of leaching times increased.The study revealed the characteristics of nitrogen accumulation and leaching in three types of farmland soil under different treatments and the main influencing factor of nitrogen accumulation.Controlling the excessive accumulation of nitrogen in the soil and optimizing nitrogen management are effective ways of reducing nitrogen loss from the soil.