Crop rotation associating a legume and the nickel hyperaccumulator Alyssum murale improves the structure and biofunctioning of an ultramafic soil (original) (raw)
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Soil microbial and Ni-agronomic responses to Alyssum murale interplanted with a legume
Applied Soil Ecology, 2018
Agromining aims to rehabilitate contaminated or natural metal-rich soils (ultramafic soils) by extracting metals of high economic importance, such as nickel (Ni), using hyperaccumulator plants and then to recover these metals for industrial purposes. Ultramafic soils are characterized by low fertility levels and this can limit yields of hyperaccumulators and metal phytoextraction. Here, we characterized the potential benefits for phytoextraction efficiency of co-cropping two plants: a Ni-hyperaccumulator (Alyssum murale; Brassicaceae) and a legume (Vicia sativa; Fabaceae). A field experiment with 3 replicates was set up in an ultramafic zone in North West Spain. Four treatments were tested: co-cropping ("Co"), fertilized mono-culture ("FMo"), non-fertilized mono-culture ("NFMo") and bulk soil ("BS"). "FMo" and "Co" treatments increased the biomass yields of A. murale by 453% and 417% respectively, compared to "NFMo". "Co" treatment generated 35% and 493% higher Ni-yields than "FMo" and "NFMo", respectively. Most of the microbial analyses showed that introducing V. sativa ("Co" treatment) into the cropping system had beneficial effects. "Co" treatment significantly modified the phenotypical structure of bacterial communities and raise the relative abundance of the phylum Bacteroidetes and reduced that of Actinobacteria. In addition, non-metric multidimensional scaling analysis of the operational taxonomic units (OTUs) showed that "Co" was clearly separate from all other treatments. Thus, this study showed that co-cropping a hyperaccumulator with a legume in Ni-agromining systems not only improves plant biomass and Ni-yields, but also enhanced some soil microbial enzymatic activities. Ameliorating agromining by replacing fertilizers would combine eco-efficient or sustainable metal recovery with soil fertility/quality improvement.
International Journal of Phytoremediation, 2019
In Albania, ultramafic outcrops cover 11% of the surface and have the potential to support nickel phytomining. In a large-scale in-situ experiment on an ultramafic Vertisols in Pojsk€ e we are studying the influence of agronomical practices on Ni phytoextraction yield of Odontarrhena chalcidica (syn. Alyssum murale). Three cropping systems were compared in three plots in 2016-2017; POJ-1 Plot (0.3 ha) was established with plants that had germinated spontaneously without any treatments; POJ-2 plot (0.3 ha) was covered by plants that had germinated spontaneously and was treated with mineral fertilizer (N50P50K50 kg ha À1); and POJ-3 Plot (400 m 2) was divided in four sub plots, where O. chalcidica was planted at a density of 4 plants m À2 on which, we neither applied fertilizer, nor NPK fertilizer (N65P65K65), pig (FPM; N260:P105:K260 þ 15 kg ha À1 N, P, K) or chicken manure (FCHM; N260:P390:K260 þ15 kg ha À1 N, P, K. Irrigation and mechanical control of weeds was done on POJ-3. After 8 months, shoot Ni concentration, biomass, and Ni yields were higher in O. chalcidica treated with manure and the cost of biomass production was smaller. Nickel yield was more promising (145 kg ha À1) than in previous field trials. This study highlights that, using manure, the Ni yield increases Ni phytomining net values, thus agromining can become an economically justifiable agricultural cropping system.
Science of The Total Environment, 2018
Most of the research dedicated to agromining has focused on cultivating a single hyperaccumulator plant, although plant diversity has been shown to positively modify soil characteristics. Hence, we compared the effect of cropping a nickel-hyperaccumulator Alyssum murale with a legume (Vicia sativa) to A. murale's monoculture, on the bacterial diversity and physico-chemical characteristics of an ultramafic soil. A pot experiment with 5 replicates was conducted in controlled conditions for 11 months. The treatments studied were: cocropping and rotation vs. mineral fertilization controls and bare soil. The introduction of legumes induced a clearly positive effect on the soil's microbial biomass carbon and nitrogen. Arylsulfatase and urease activities tended to be enhanced in the co-cropping and rotation treatments and to be lessened in the mineral fertilization treatments. However, β-glucosidase and phosphatase activities were seen to decrease when legumes were used. Our results showed that the rotation treatment induced a higher organic matter content than the fertilized control did. Actinobacteria was the most-represented bacterial phyla and had lower relative abundance in treatments associating legumes. Conversely, the relative abundance of Acidobacteria and Gemmatimonadetes phyla increased but not significantly in treatments with legumes. The relative abundance of Chloroflexi phylum was shown to be significantly higher for the fertilized rotation control. The relative abundance of β-Proteobacteria subphylum increased but not significantly in treatments with legumes. NMDS analysis showed a clear separation between planted treatments and bare soil and between co-cropping and rotation and fertilized controls. Shannon index
Developing Sustainable Agromining Systems in Agricultural Ultramafic Soils for Nickel Recovery
Frontiers in Environmental Science, 2018
Ultramafic soils are typically enriched in nickel (Ni), chromium (Cr), and cobalt (Co) and deficient in essential nutrients, making them unattractive for traditional agriculture. Implementing agromining systems in ultramafic agricultural soils represent an ecological option for the sustainable management and re-valorisation of these low-productivity landscapes. These novel agroecosystems cultivate Ni-hyperaccumulating plants which are able to bioaccumulate this metal in their aerial plant parts; harvested biomass can be incinerated to produce Ni-enriched ash or "bio-ore" from which Ni metal, Ni ecocatalysts or pure Ni salts can be recovered. Nickel hyperaccumulation has been documented in ∼450 species, and in temperate latitudes these mainly belong to the family Brassicaceae and particularly to the genus Odontarrhena (syn. Alyssum pro parte). Agromining allows for sustainable metal recovery without causing the environmental impacts associated with conventional mining activities, and at the same time, can improve soil fertility and quality and provide essential ecosystem services. Parallel reductions in Ni phytotoxicity over time would also permit cultivation of conventional agricultural crops. Field studies in Europe have been restricted to Mediterranean areas and these only evaluated the Ni-hyperaccumulator Odontarrhena muralis s.l. Two recent EU projects (Agronickel and LIFE-Agromine) have established a network of agromining field sites in ultramafic regions with different edapho-climatic characteristics across Albania, Austria, Greece and Spain. Soil and crop management practices are being developed so as to Kidd et al. Sustainable Agromining Systems for Nickel Recovery optimize the Ni agromining process; field studies are evaluating the potential benefits of fertilization regimes, crop selection and cropping patterns, and bioaugmentation with plant-associated microorganisms. Hydrometallurgical processes are being up-scaled to produce nickel compounds and energy from hyperaccumulator biomass. Exploratory techno-economic assessment of Ni metal recovery by pyrometallurgical conversion of O. muralis s.l. shows promising results under the condition that heat released during incineration can be valorized in the vicinity of the processing facility.
HortScience
The ability of certain crops to improve soil fertility or physical conditions has long been recognized. As early as the Chow dynasty (1134-247 B.C.) in China, there were reports of crops whose value for soil improvement was "greater than silkworm excrement" (Pieters, 1927). Romans around the time of Christ likewise waxed eloquently on the value of green manures, as in this line from Virgil: "Sow your wheat on land where grew the bean, the slender vetch or the fragile stalks of the bitter lupine." The potential benefits of soil-improving crops (SIC-s) are many and varied. In addition to the continued use of legumes as a source of biologically fixed N, in more recent years, SICs have been commonly included in cropping systems to retard soil erosion and build up organic matter. In addition to these objectives, a 1988 survey of New England farmers using cover crops revealed that nearly half expected to derive some weed control from the SIC (Schonbeck, 1988). Fewer used SIC to conserve nutrients or make certain elements (such as P) more available, or to control insects and pests. Growers with soil compaction problems may grow a deeprooted SIC to break up dense soil layers (Foulds, 1989). No single SIC can impart all the above benefits to a particular cropping system. In addition, there are some potential negative effects of SICs, including: depletion of soil moisture, lowering of spring soil temperatures, disruption of field operations, allelopathy, and the creation of habitat for harmful organisms. Even nitrate pollution of groundwater is a potential problem with the improper management of legumes in cropping systems. The realized value of the SIC to a particular cropping system will, of course, depend on the selection of species, management of those species, and interaction with the rest of the cropping system, including crops, weather, weed and pest pressures, and other components. SOIL-IMPROVING CROPS IN VEGETABLE SYSTEMS Constraints Agronomic literature in the past 10 years has become weighty with research on the use of SICs in field crop rotations (
Journal of Geochemical Exploration, 2019
Ultramafic soils are usually marginal in macronutrients (nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca)) for growth of crop plants. Commercial nickel (Ni) agromining is dependent on attaining high yield and high Ni concentration in harvestable biomass of Ni hyperaccumulator species. We previously reported on the biomass responses of two promising tropical 'metal crops' (Phyllanthus rufuschaneyi and Rinorea cf. bengalensis) to rates of N, P, and K fertilisers. Calcium, sulphur (S) and organic matter amendments have varied effects on the biomass production and Ni uptake in temperate Ni hyperaccumulator species used in agromining, but the trends in tropical 'metal crops' are not reported to-date. We investigated the effects of these amendments on the growth performance and the Ni (and other elements) uptake in P. rufuschaneyi and R. bengalensis. The experiments consisted of a large 12-month randomised growth trial in large pots in Sabah (Malaysia) using ultramafic soils under different treatment levels of soluble Ca and S, and organic matter amendments. We found that Ca and S additions had no significant effects on the growth of P. rufuschaneyi and R. bengalensis. Organic matter amendments had strong positive effect on the growth of R. bengalensis (p <0.05), but we recorded significant negative growth response in P. rufuschaneyi. Whereas Ca and S additions improved the Ni uptake in these species, organic matter amendments significantly reduced the shoot Ni concentrations in both species. Our findings indicate that Ca and S additions are important in the agronomy of tropical 'metal crops' to be used in economic Ni agromining, but organic matter amendments may not be useful.
Ultramafic soils and nickel phytomining opportunities: A review
Revista Brasileira de Ciência do Solo
Ultramafic soils are originated from ultramafic rocks such as peridotite and serpentinite and are highly enriched in metals (e.g., Ni, Cr, and Co) and depleted in plant nutrients (e.g., P, K, and Ca). Such characteristics make these soils unfavorable for agriculture and have raised environmental concerns on metal release to the environment. From another perspective, ultramafic soils host a diverse flora with higher endemism than surrounding non-ultramafic areas, which has provided scientists with an opportunity to investigate the evolutionary genetics of plant adaptation. Some plant species adapted to these stressful edaphic conditions developing the ability to accumulate uncommonly high metal concentrations in the harvestable biomass. Such species, called metal hyperaccumulators, can extract metals from ultramafic soils, especially Ni, in a circular economy approach in which the metal-rich biomass is incinerated to generate valuable bio-ores. Phytomining promises to turn ultramafic soils and low-grade ore bodies into economically viable alternatives to metal extraction. Here, we review the current knowledge on ultramafic soils and the most promising hyperaccumulators used to exploit them in temperate and tropical climates. In the tropics, including Brazil, the search for new hyperaccumulator candidates for phytomining and the knowledge to crop these species is incipient and holds untapped opportunities. Despite the feasibility of the phytomining chain has been proven, large-scale demonstrations of profitability are needed to establish the technology.
Environmental and Experimental Botany, 2016
Low soil fertility in ultramafic soils limits the efficiency of nickel phytoextraction. Developing more efficient cropping systems for agromining can be achieved by the association of a hyperaccumulator with a legume by enhancing soil fertility. However, legume crops can result sensitive to ultramafic soil conditions, including nickel Ni availability. We assessed here whether Lens culinaris is adapted to ultramafic environments by growing on soils displaying a wide range of Ni concentrations and consequently producing functional nodules. The soil was enriched with different Ni concentrations ([Ni]) (0-90 mg Ni kg À1). Natural 15 N abundance was used to assess N 2 fixation (%Ndfa). Biotic parameters were investigated (nodule number, Ni, carbon and nitrogen concentrations, plant biomass. . .). Soil parameters were investigated (total [Ni], DTPA-extractable Ni, C and N concentrations. . .). Most of the physicochemical and biological parameters were significantly affected by the increased soil [Ni]. Nodule numbers per plant was lower under high [Ni] than control (soil without Ni). Nodules lost their capacities to fix N 2 under high Ni addition (90 mg Ni kg À1). For many parameters, there were no significant differences between control and treatments up to 60 mg of Ni kg À1 added to the soil. Lentil is able to grow on a soil containing amounts of Ni-DTPA similar to those generally found in serpentine soils. It could be used in association with a hyperaccumulator plant as a nitrogen provider in order to optimize Ni agromining. 2016 Elsevier B.V. All rights reserved.
Using hyperaccumulator plants to phytoextract soil Ni and Cd
Zeitschrift für Naturforschung. C, Journal of biosciences
Two strategies of phytoextraction have been shown to have promise for practical soil remediation: domestication of natural hyperaccumulators and bioengineering plants with the genes that allow natural hyperaccumulators to achieve useful phytoextraction. Because different elements have different value, some can be phytomined for profit and others can be phytoremediated at lower cost than soil removal and replacement. Ni phytoextraction from contaminated or mineralized soils offers economic return greater than producing most crops, especially when considering the low fertility or phytotoxicity of Ni rich soils. Only soils that require remediation based on risk assessment will comprise the market for phytoremediation. Improved risk assessment has indicated that most Zn + Cd contaminated soils will not require Cd phytoextraction because the Zn limits practical risk from soil Cd. But rice and tobacco, and foods grown on soils with Cd contamination without corresponding 100-fold greater Z...
Environmental Science and Pollution Research, 2021
Contamination of soils by nickel (Ni) has become a serious environmental problem throughout the world, and this substance wields dangerous effects on the ecosystem and food chain. A pot experiment was conducted to examine the effect of rice straw (RS), rice straw biochar (BI) and calcite (CC) at 1% and 2% application rates in a Ni contaminated soil. The objective was to potentially stabilize Ni and reduce its bioavailability to spinach (Spinacia Oleracea L.). Spinach plants were grown in a Ni contaminated Ultisol (commonly known as a red clay soil). Physiological results indicated that a BI 2% application rate signi cantly increased the photosynthetic rate by 4-18.6 µmol m 2 S − 1 and transpiration rate by 1.7-8.9 mmol m 2 S − 1. Similarly, growth parameters for root and shoots dry biomass increased 1.7-and 6.3-fold, respectively, while essential nutrients were enhanced in the spinach plant compared to those in the untreated soil (CK). Moreover, adding amendments signi cantly decreased CaCl 2 extractable Ni by 62.5% 94.1%, and 87.2%, while the toxicity characteristics leaching procedure (TCLP) fell by 26.7%, 47.8%, and 41.7% when using RS, BI and CC, respectively, at 2% compared to CK. The Ni concentrations in the spinach roots declined by 51.6%, 73.3% and 68.9%, and in the shoots reduced by 54.1%, 76.7% and 70.8% for RS, BI and CC, at a 2% application rate, respectively. Bio-concentration factor (BCF) and translocation factor (TF) dropped signi cantly by as much as 72.7% and 20%, for BI 2% application rate. Results of the present study clearly indicated that biochar potential soil amendments for Ni stabilization, thereby reducing its bioavailability in the Ni contaminated soil. This process enhanced the safety of food to be consumed and mitigated security risks.