Aims

Agromining aims to improve the fertility of naturally metal-rich soils by extracting metals, such as nickel (Ni), using hyperaccumulator plants. Ultramafic soils are characterized by low fertility levels, limiting hyperaccumulator yields. Here, we characterize the potential benefits for phytoextraction efficiency of co-cropping a Ni-hyperaccumulator (Odontarrhena chalcidica) and a legume (Vicia sativa), following a two-year field experiment.

Methods

A two-year field experiment was set up in an ultramafic zone in North-West Spain. Three treatments were tested: co-cropping, fertilized control with ammonium nitrate and non-fertilized control.

Results

Over the 2 years, co-cropping increased O. chalcidica’s biomass by 24% and 403% compared to fertilized and non-fertilized controls, respectively. Moreover, co-cropping had higher Ni-yields for both years, while fertilization had a negative effect on soil parameters. A non-metric multidimensional scaling analysis of the operational taxonomic units showed that the soil bacterial diversity changed over time. Soil exchangeable Ni and organic carbon influenced the phyla’s relative abundance. Metabolic genes were dominant and their relative abundances increased over time with co-cropping.

Conclusion

Pluriannual co-cropping of a hyperaccumulator with a legume improved both hyperaccumulator and Ni yields. In contrast, mineral fertilization was shown to be detrimental to some soil microbial parameters. Thus, ameliorating agromining by replacing mineral fertilizers would combine an eco-efficient strategy with sustainable metal recovery.

中文翻译：

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在超镁铁质土壤上使用豆类农作物与豆类共作作物进行的为期两年的镍农化研究：植物生物量，镍产量以及生物分类和细菌功能多样性的时间变化

目的

农业发展的目的是通过使用超蓄积植物提取镍（Ni）等金属，从而提高富含天然金属的土壤的肥力。超镁铁质土壤的特点是肥力低，限制了高蓄积作物的产量。在这里，我们进行了为期两年的田间试验，研究了共同种植Ni-超蓄积剂（Odontarrhena chalcidica）和豆类（Vicia sativa）对植物提取效率的潜在益处。

方法

在西班牙西北部的超镁铁质地带建立了一个为期两年的野外实验。测试了三种处理方式：共作，硝酸铵施肥对照和非施肥对照。

结果

在过去的两年中，与施肥和未施肥的农作物相比，共作物分别使稻草的生物量增加了24％和403％。而且，连作两个年度的镍产量都较高，而施肥对土壤参数有负面影响。对操作分类单位的非度量多维标度分析表明，土壤细菌多样性随时间变化。土壤可交换的镍和有机碳影响门的相对丰度。代谢基因占主导地位，并且随着时间的推移，它们的相对丰度随着时间的增长而增加。

结论

与豆科植物一起对多年生超级作物进行联合修剪可以提高超级积累和镍的产量。相反，矿物施肥被证明对某些土壤微生物参数有害。因此，通过替代矿物肥料来改善农业生产将结合生态高效策略和可持续的金属回收。