炭肥混施下土壤养分缓释特征与芥菜镉富集响应模拟

土壤养分有效性是影响重金属富集植物的重要因素,为研究炭肥混施下土壤养分缓释特征及芥菜镉富集趋势,试验设置施肥比例(分别为基准施肥量的0、20%、40%、70%、100%,基准施肥量为N 350 kg/hm^2、P_2O5180 kg/hm^2、K_2O 180 kg/hm^2)以及施炭比例(炭肥质量比0、3%、9%)完全组合设计。结果表明:基于Logistic曲线模型模拟炭肥混施下土壤养分缓释特征及镉富集趋势效果较好,均方根误差占实测平均值的3. 29%～8. 37%且R2不小于0. 957 0。炭肥混施下土壤养分高效缓释的施肥比例区间为0. 99%～55. 18%,相比未施炭的有效氮、有效磷最大缓释效率值分别提升49. 17%～90. 00%、13. 25%～37. 35%,高效缓释下土壤养分含量提高17. 38%～40. 93%。镉富集下芥菜生物量通过土壤养分高效缓释增长119. 65%～263. 36%,且地上部相比根部的生物量高效累积最大效率值提高166. 67%～300. 00%,有效氮、有效磷响应区间分别扩大150. 00%、12. 51%,为镉由根部向地上部的转运提供动力基础;芥菜镉含量、富集系数在土壤养分高效缓释区间增长97. 79%～201. 96%。为满足芥菜镉高效富集并兼顾肥料节约,通过模型反算得炭肥混施策略优化为:9%施炭下有效氮、有效磷和有效钾肥的比例分别为60. 58%、61. 32%、21. 48%。

Soil Nutrient Release Characteristics and Response Simulation of Cadmium Accumulation in Mustard Plants under Mixed Bio-carbon and Fertilizer

Soil nutrient availability is an important factor influencing heavy metal enrichment plant. The characteristics of soil nutrient slow release and the tendency of cadmium accumulation of mustard were studied. A complete combination design of fertilization rate (0, 20%, 40%, 70% and 100% of the benchmark fertilizer application amount respectively, and the benchmark fertilizer application amount was N350kg/m2, P2O5 180kg/hm2 and K2O 180kg/hm2) and carbon application ratio (carbon fertilizer quality ratio of 0, 3% and 9%) were set up in the experiment. The results showed that the soil nutrient slow release characteristics and cadmium enrichment trend were well fitted based on the Logistic curve model, and the measured root mean square error ratio was 3.29%~8.37%, and R2 was no less than 0.9570. The fertilizer proportion of soil nutrient with high efficient and slow release under combined application of carbon fertilizer was 0.99%~55.18%, the maximum sustained release efficiency of nitrogen and phosphorus was increased by 49.17%~90.00%, 13.25%~37.35%, respectively, and the soil nutrient content was increased by 17.38%~40.93%, compared with that without carbon application. The biomass of mustard with cadmium concentration was increased by 119.65%~263.36% through efficient slow release of soil nutrients, and the maximum efficiency value of the biomass in the aboveground part was increased by 166.67%~300.00% compared with the biomass in the root part. The content of cadmium and enrichment coefficient of mustard greens was increased by 97.79%~201.96% in the highly efficient slow release interval of soil nutrients. Therefore, in order to meet the requirement of both high efficiency and high concentration of mustard cadmium and fertilizer conservation, the combined application strategy of carbon fertilizer was optimized as follows: the proportion of nitrogen, phosphorus and potash fertilizer under 9% carbon was 60.58%, 61.32% and 21.48%.