Jacek Krzyżak

Progress in upscaling Miscanthus biomass production for the European bio-economy with seed-based hybrids

Field trials in Europe with Miscanthus over the past 25 years have demonstrated that interspecies hybrids such as M. × giganteus (M × g) combine both high yield potentials and low inputs in a wide range of soils and climates. Miscanthus hybrids are expected to play a major role in the provision of perennial lignocellulosic biomass across much of Europe as part of a lower carbon economy. However, even with favourable policies in some European countries, uptake has been slow. M × g, as a sterile clone, can only be propagated vegetatively, which leads to high establishment costs and low multiplication rates. Consequently, a decade ago, a strategic decision to develop rapidly multiplied seeded hybrids was taken. To make progress on this goal, we have (1) harnessed the genetic diversity in Miscanthus by crossing and progeny testing thousands of parental combinations to select several candidate seed‐based hybrids adapted to European environments, (2) established field scale seed production methods with annual multiplication factors >1500×, (3) developed the agronomy for establishing large stands from seed sown plug plants to reduce establishment times by a year compared to M × g, (4) trialled a range of harvest techniques to improve compositional quality and logistics on a large scale, (5) performed spatial analyses of yield potential and land availability to identify regional opportunities across Europe and doubled the area within the bio‐climatic envelope, (6) considered on‐farm economic, practical and environmental benefits that can be attractive to growers. The technical barriers to adoption have now been overcome sufficiently such that Miscanthus is ready to use as a low‐carbon feedstock in the European bio‐economy.

Chlorophyll a Fluorescence in Evaluation of the Effect of Heavy Metal Soil Contamination on Perennial Grasses

Chlorophyll a fluorescence gives information about the plant physiological status due to its coupling to the photosynthetic electron transfer chain and to the further biochemical processes. Environmental stresses, which acts synergistically, disturbs the photosynthesis. The OJIP test, elaborated by Strasser and co-workers, enables comparison of the physiological status of plants grown on polluted vs. control areas. The paper shows that the Chl a measurements are very useful tool in evaluating of heavy metal ions influence on perennial grasses, tested as potential phytoremediators. Among 5 cultivars tested, the highest concentration of Cd and Zn ions, not associated with the yield reduction, was detected in the biomass of tall fescue cv. Rahela. Chl a fluorescence interpreted as double normalized curves pointed out Rahela as the outstanding cultivar under the HM ions stress.

A Heavy Metal Environmental Threat Resulting from Combustion of Biofuels of Plant Origin

Several assessments of the potential biomass supply in Europe show that the best means of biomass production are growing energy crops on agricultural land. Cultivation of energy crops on agricultural areas might lead to accumulation of heavy metals in plant tissues and reemission of contaminants into the atmosphere during combustion. The goal of the present study was to assess how soil contamination influences heavy metals accumulation in energy plant tissues. The current paper presents the results of screening of selected plants (Spartina pectinata, Miscanthus sp., Helianthus tuberosus, Elymus elongatus) conducted in uncontaminated region of Poland (North-Eastern part of the country) aimed at finding natural abilities to uptake small amounts of heavy metals and accumulate is in the plant tissue. Based on this screening, Miscanthus sp. was tested on heavy metal contaminated arable soil in Southern Poland. This species accumulates high amounts of metals what may cause high emission of contaminants during biomass combustion.

Relationships between soil parameters and physiological status of Miscanthus x giganteus cultivated on soil contaminated with trace elements under NPK fertilisation vs. microbial inoculation

Crop growth and development can be influenced by a range of parameters, soil health, cultivation and nutrient status all play a major role. Nutrient status of plants can be enhanced both through chemical fertiliser additions (e.g. N, P, K supplementation) or microbial fixation and mobilisation of naturally occurring nutrients. With current EU priorities discouraging the production of biomass on high quality soils there is a need to investigate the potential of more marginal soils to produce these feedstocks and the impacts of soil amendments on crop yields within them. This study investigated the potential for Miscanthus x giganteus to be grown in trace element (TE)-contaminated soils, ideally offering a mechanism to (phyto)manage these contaminated lands. Comprehensive surveys are needed to understand plant-soil interactions under these conditions. Here we studied the impacts of two fertiliser treatments on soil physico-chemical properties under Miscanthus x giganteus cultivated on Pb, Cd and Zn contaminated arable land. Results covered a range of parameters, including soil rhizosphere activity, arbuscular mycorrhization (AM), as well as plant physiological parameters associated with photosynthesis, TE leaf concentrations and growth performance. Fertilization increased growth and gas exchange capacity, enhanced rhizosphere microbial activity and increased Zn, Mg and N leaf concentration. Fertilization reduced root colonisation by AMF and caused higher chlorophyll concentration in plant leaves. Microbial inoculation seems to be a promising alternative for chemical fertilizers, especially due to an insignificant influence on the mobility of toxic trace elements (particularly Cd and Zn).

Heavy Metal Uptake by Novel Miscanthus Seed-Based Hybrids Cultivated in Heavy Metal Contaminated Soil

Abstract When heavy metal contaminated soils are excluded from food production, biomass crops offer an alternative commercial opportunity. Perennial crops have potential for phytoremediation. Whilst the conditions at heavy metal contaminated sites are challenging, successful phytoremediation would bring significant economic and social benefits. Seed-based Miscanthus hybrids were tested alongside the commercial clone Miscanthus × giganteus on arable land, contaminated with Pb, Cd and Zn near Katowice. Before the randomized experimental plots were established (25m2 plots with plant density 2/m2) ‘time-zero’ soil samples were taken to determine initial levels of total (aqua regia) and bioavailable (CaCl2 extraction) concentration of Pb, Cd and Zn. After the growing season plant material was sampled during autumn (October, green harvest) and winter (March, brown harvest) to determine differences in heavy metal uptake. Results after the first growing season are presented, including the plot establishment success, biomass yield and heavy metal uptake.

Harvest date and leaf:stem ratio determine methane hectare yield of miscanthus biomass

The suitability of miscanthus biomass for anaerobic digestion has already been confirmed by several studies. However, it is rarely used as feedstock in biogas plants, mainly due to uncertainty about the optimal harvest regime with regard to the long‐term methane hectare yield and resilience of the crop to green cutting. The recommended green‐cut date for the only commercially available genotype Miscanthus × giganteus (M×g) ranges from September to November. This timeframe is too broad for agricultural practice and needs to be both narrowed down and further specified for different genotypes. The aim of this study was to identify the most suitable harvest window for an autumn green cut of miscanthus, which delivers both a high dry matter and methane yield while securing the long‐term productivity of the crop. A further objective was to quantify the effect of genotypic differences, such as leaf to stem ratio, on the substrate‐specific biogas and methane yield. For these purposes, a field trial with four genotypes (M×g, GNT1, GNT3, Sin55) was conducted over 2 years (2016/2017) and harvested at 2‐week intervals on three dates between mid‐September to mid‐October. Methane hectare yield ranged from 3,183 m³ CH4 ha−1 a−1 (Sin55) to 5,265 m³ CH4 ha−1 a−1 (M×g), which is mainly influenced by dry matter yield. The substrate‐specific methane yield was higher for the leaf (311.0 ml CH4 (g oDM)‐1) than the stem fraction (285.1 ml CH4 (g oDM)‐1) in all genotypes due to lower lignin content of leaves. Of all genotypes, M×g showed the highest and Sin55 the lowest nutrient use efficiency. We conclude that miscanthus in Germany should be harvested in October to maximize methane yields and nutrient recycling and minimize yield reduction. Additionally, to increase methane hectare yields even further, future miscanthus breeding should focus on a higher leaf proportion.

Possibility of Using Energy Crops for Phytoremediation of Heavy Metals Contaminated Land—A Three-Year Experience

Heavy metal soil contamination is a worldwide problem. The affected sites could be either sites of a former industrial activity or arable land located in their vicinity. The presence of heavy metals in excessive quantities renders these sites idle or underused due to contamination and lack of efficient ways to remediate. Phytoremediation driven energy crops production may be a promising alternative for the management of these sites. A four year field experiment has been established on heavy metal (HM) contaminated sites located in Bytom, Upper Silesia Industrial Region, Southern Poland (arable land) and Leipzig, Germany (post-industrial site). The objective for this experiment was to distinguished energy crop species optimal with respect to both: energy crop yield and phytoremediation potential. The testing involves the following pre-selected plant species: miscanthus (Miscanthus x giganteus), virginia mallow (Sida hermaphrodita), cordgrass (Spartina pectinata), and switchgrass (Panicum virgatum). The experimental trials were established in May 2014. Both sites were treated as follows: (i) K—Control, no treatment; (ii) NPK—NPK standard fertilization, applied to the soil before the experiment; (iii) INC—Commercial microbial inoculum Emfarma Plus®, ProBiotics Poland. The presented data were collected after the third growing season; heavy metal uptake for each of the species and experimental options were determined. Levels of the bioavailable content of heavy metals in the soil seem to be the main factor responsible for the differences in the metal uptake by the plants. Plant species cultivated at the German site were characterized by low metal concentration in shoots, except P. virgatum which accumulated a high amount of zinc, even if the bioavailability of this metal in soil was low. The highest lead uptake was observed for M. x giganteus and P. virgatum, while the highest cadmium content was found for S. hermaphrodita grown on a contaminated arable soil in Bytom. Cultivation of energy crops on HM contaminated areas could be a solution for remediating these sites while increasing their economic value.

Macroelements and heavy metals content in energy crops cultivated on contaminated soil under different fertilization—case studies on autumn harvest

Heavy metals (HMs) contamination of soils is a major problem occurring worldwide. Utility of energy crops for biofuel feedstock production systems offers a feasible solution for a commercial exploitation of an arable land contaminated with HMs. Experiments involved field testing of Miscanthus x giganteus and Spartina pectinata cultivated on HMs-contaminated soil with standard NPK fertilizers and commercially available microbial inoculum. Biomass yield, water content, macronutrients (N, P, K, Mg, Ca), and heavy metal (Cd, Pb, Zn) concentrations in plant shoots were assessed at the end of the first and the second growing season. Independently of the applied fertilizers, Miscanthus x giganteus produced higher biomass yield while contrary results were obtained for S. pectinata. Higher HMs content in plants influenced the status of the mineral macronutrients in particular N and K. Occurrence of hasted senescence induced by drought in the second growing season caused reduction in the concentrations of all elements (except Pb), due to earlier rhizomes relocation.

Photosynthetic Apparatus Efficiency of Sida Hermaphrodita Cultivated on Heavy Metals Contaminated Arable Land Under Various Fertilization Regimes

Abstract Contaminated and marginal lands are favourable place for biomass feedstock establishment, especially due to European Union directive 2009/28/EC. This strategy not only cover local demand for energy and heat but also can be valuable in those land phytomanagment. The second-generation perennial energy crop species are the most feasible for such purpose. We studied the impact of two different fertilizer treatments on plant physiological parameters associated with photosynthesis, heavy metals (HMs) and primary macronutrients accumulation in Sida hermaphrodita cultivated on HMs contaminated soil under field conditions. NPK fertilized plants showed the highest values of photosynthetic parameters at the beginning of growing season when compared to control and microbial inoculated plants. However, at the end of the growing season inoculated and control plants showed better photosynthetic performance than NPK treated. NPK fertilizer caused higher Cd and Zn shoot concentrations while microbial inoculation caused higher K and the lowest N and P concentrations in shoot. Due to Cd, Pb and Zn concentrations in plants which should not result in alleviation of photosynthetic apparatus efficiency and biomass production it could be summarize that Sida hermaphrodita is a suitable plant for cultivation on land contaminated with HMs under different fertilization regimes.

PHYSICO-CHEMICAL PROPERTIES OF THE SOLID AND LIQUID WASTE PRODUCTS FROM THE HEAVY METAL CONTAMINATED ENERGY CROPS GASIFICATION PROCESS

Treatment of the soil by plants (phytoremediation), associated with the production of biomass for energy purposes, carries a number of significant problems with a practical and technical point of view. They concern mainly the way of the thermal conversion of biomass to energy production in an efficient and environmentally safe way. One way may be gasification. This process involves the conversion of organic matter into a combustible gas mixture by partial oxidation at high temperature under the influence of gasifying agent (air, oxygen, steam, or mixtures of these components). Gasification aim is to obtain a combustible gas. Unfortunately, the formation of gas also accompanied by the formation of solid and liquid waste products. The paper presents the results of basic physicochemical properties of solid (ash) and liquid (tar) waste products of the gasification process of the heavy metal contaminated energy crops. The gasification process has carried out in a laboratory fixed bed reactor. Three types of energy crops: Miscanthus x giganteus, Sida hermaphrodita and Spartina Pectinata were used. The experimental plots were established on heavy metal contaminated arable land located in Bytom (southern part of Poland, Silesian Voivodship). The results show that the gasification process, promotes the migration of harmful substances such as heavy metals from fuel to the solid phase.