66
Phytotechnology with Biomass Production
No single plant species will show all these traits; however, collection of
germplasm from a diversity of accumulator plant species, testing potentials
for agronomic yield and element accumulation on a variety of substrates
with various soil management, and either conventional breeding or genetic
manipulation should contribute to generate optimum “phytominers”.
In conclusion, from an agroecosystem point of view, a combination of the following practices is the most promising approach (Kidd et al., 2018; Li et al., 2003;
Nkrumah et al., 2016; Robinson et al., 2009; Tang et al., 2012; Wang et al., 2020):
• soil management
• soil amendments (regulation of pH, inorganic, and organic
fertilizers)
• ploughing → decrease of soil heterogeneity (patchiness of concentration of target elements); translocation of target elements
from deeper soil horizons close to soil surface
• crop management
• planting: seeding depth, seed bed preparation, germination
requirements, direct seeding, seed pelletization, transplanting
• planting density (dependent on soil physical properties, organic
matter and nutrient levels, plant species)
• plant life form (annual, perennial)
• co-cropping/intercropping → affects conditions in the rhizosphere → increased bioavailability of target element(s)
• weed control
• harvest methods: machinery for aboveground biomass, time
of harvesting (effect on element and bioenergy yield); double
harvesting
• plant breeding
Widening the scope from the earlier focus on (hyper-)accumulators to the
whole soil–plant agrosystem has been mirrored in the term “agromining”
(Nkrumah et al., 2018). “Metal crops”, i.e., plant species accumulating heavy
metals, precious elements, or REEs, with a high biomass yield, have now
become the focus of research (Li et al., 2020).
4.5 Economic Viability and Environmental Considerations
The agro-ecological expenditures related to plant cultivation as discussed
above are only part of the costs of a complete phytomining approach, which
also include processing of the plant biomass for recovery of the economically
Phytotechnology with Biomass Production
No single plant species will show all these traits; however, collection of
germplasm from a diversity of accumulator plant species, testing potentials
for agronomic yield and element accumulation on a variety of substrates
with various soil management, and either conventional breeding or genetic
manipulation should contribute to generate optimum “phytominers”.
In conclusion, from an agroecosystem point of view, a combination of the following practices is the most promising approach (Kidd et al., 2018; Li et al., 2003;
Nkrumah et al., 2016; Robinson et al., 2009; Tang et al., 2012; Wang et al., 2020):
• soil management
• soil amendments (regulation of pH, inorganic, and organic
fertilizers)
• ploughing → decrease of soil heterogeneity (patchiness of concentration of target elements); translocation of target elements
from deeper soil horizons close to soil surface
• crop management
• planting: seeding depth, seed bed preparation, germination
requirements, direct seeding, seed pelletization, transplanting
• planting density (dependent on soil physical properties, organic
matter and nutrient levels, plant species)
• plant life form (annual, perennial)
• co-cropping/intercropping → affects conditions in the rhizosphere → increased bioavailability of target element(s)
• weed control
• harvest methods: machinery for aboveground biomass, time
of harvesting (effect on element and bioenergy yield); double
harvesting
• plant breeding
Widening the scope from the earlier focus on (hyper-)accumulators to the
whole soil–plant agrosystem has been mirrored in the term “agromining”
(Nkrumah et al., 2018). “Metal crops”, i.e., plant species accumulating heavy
metals, precious elements, or REEs, with a high biomass yield, have now
become the focus of research (Li et al., 2020).
4.5 Economic Viability and Environmental Considerations
The agro-ecological expenditures related to plant cultivation as discussed
above are only part of the costs of a complete phytomining approach, which
also include processing of the plant biomass for recovery of the economically