镉污染下不同类型水稻土氮素供应特征及其影响因素

污染条件下的土壤氮素供应影响了作物生产和植物生态修复。采用温室盆栽试验，研究了两种剂量镉污染下我国21种水稻土无机氮的供应特征和影响因素。结果表明：淹水10天后，不同水稻土土壤溶液无机态氮含量变幅为1.42 ~ 70.40 mg/L （(平均值为16.76 mg/L）)，其中NH4+-N和NO3--N分别占62.5% 和33.7%；与施肥对照相比，镉污染降低了大多数水稻土土壤溶液无机态氮的含量，平均降幅为58.4%，主要是由土壤溶液NH4+-N含量下降所致；土壤溶液NO3--N含量受镉污染的影响程度则因土壤类型而异。基于典范对应分析的偏因子分析（(VPA）)表明镉污染对水稻土土壤溶液无机氮含量的影响最大，其次是土壤类型，施肥影响最小，三类因子单独作用的影响比例分别为40.38%、6.51% 和0.05%。镉污染下，pH、CEC和土壤质地显著影响水稻土无机氮供应，其中土壤pH是镉污染条件下影响NH4+-N含量变化的首要因子。

Characteristics and Determinants for Nitrogen Supply of Different Types of Paddy Soils Under Spiked-cadmium Conditions

Nitrogen supply of paddy soils under contamination is important for crop production and plant bioremediation. Pot experiments were carried out to study N supply characteristics and its influencing factor of 21 types of paddy soils under two spiked-cadmium levels. The results showed that the total inorganic nitrogen (TIN) contents ranged from 1.42 to 70.40 mg/L (mean at 16.76 mg/L), , in which NH4+-N and NO3--N amounted to 62.5% and 33.7%, , respectively. In comparison to control treatment (fertilizion with NPK without Cd addtion), , Cd treatment decreased soil solution TIN contents for most types of paddy soils, , which was mainly caused by the decline in NH4+-N contents. Changes of soil solution NO3--N contents with Cd contamination were soil type-dependent. CCA-based variation partitioning analysis (VPA) indicated that solution inorganic nitrogen supply of paddy soils was most affected by Cd contamination (40.38%), , less affected by soil type (6.51%), , and least affected by fertilization (0.05%). Soil pH, , CEC and texture were important factors influencing inorganic nitrogen supply of paddy soils under Cd contamination, , among which soil pH was the foremost factor for soil solution ammonium.