保障蔬菜安全生产中十分重要的是研究推导出适用于蔬菜安全生产的土壤镉阈值。在高自然背景地区，可提取态镉的土壤阈值对于食品安全和环境管理显得尤为重要。本研究采用物种敏感性分布法，耦合土壤老化、生物有效性、以及土壤性质影响，推导土壤全量镉和可提取态镉的阈值。在5个文献数据库中，利用指定的关键字对已发表论文中的数据进行筛选，共筛选出90种符合条件的蔬菜品种。利用土壤-植物系统中镉迁移转化模型对生物积累数据进行归一化处理后，种内变异性降低18.3 ~ 84.4%。利用物种敏感性分布曲线推导出保护95%的物种不超标的土壤镉浓度，即HC5值。进而提出了基于外源添加法推导的土壤镉阈值，该阈值可以用基于土壤有机质和pH的连续性方程表示。全量镉和EDTA可提取态镉的阈值分别为0.23 ~ 0.61 mg kg^-1和0.09 ~ 0.25 mg kg^-1。利用田间试验数据对推导的阈值模型进行验证。大部分的预测值都小于由田间试验计算出的HC5值，说明本阈值是保守可行的。综上所述，本研究为建立蔬菜种植土壤镉阈值提供了以保障蔬菜产品质量安全的科学依据。

Received  11 November, 2017    Accepted  28 January, 2018

A field plot experiment in a calcareous soil with wheat and maize rotation was carried out for 2 yr. The study aimed to investigate the effects of biosolids (sewage sludge or chicken manure) application on nitrogen (N) and phosphorus (P) accumulation in soils and to develop a model for the effects of biosolids application on available P (Olsen-P) accumulation in soils, by which the quantities of biosolids that can be safely applied to agricultural soils were estimated. The results showed that heavy application of biosolids to agricultural soils based on the N requirement of a wheat-maize rotation cropping system will oversupply P. Soil total N was increased by 0.010 g kg-1 at application rate of 1 ton sewage sludge per hectare. The high ratio of N to P in grains of wheat and maize (from 4.0 to 7.6) and low ratio of N to P in biosolids (<2) led to more surplus P accumulated in soils. Although plant yields and P uptake by plants increased with increasing quantities of applied biosolids in soils, there was still an average 2.87 mg kg-1 increase in Olsen-P in the plough layer treated with biosolids for every 100 kg P ha-1 surplus. A predictive model was developed based upon the initial Olsen-P in soils, P input rates, crop yield, soil pH, and cultivation time. From the model, it is suggested that sewage sludge could be applied to calcareous soils for 12 yr using the recommended application rate (9 tons ha-1 yr-1). The field results will be helpful in achieving best management of biosolids application for agricultural production and environmental protection.