Comparison of two perennial energy crops for biomass production at the end of their life cycle

Nowadays fossil fuels are decreasing, causing the world's interest in renewable energy sources to rapidly grow. One of the most interesting renewable and ecologically pure fuels is biomass, which is considered to be carbon neutral. Biomass is a promising source of energy, as it can be used directly as an energy resource. Its quality characteristics such as gross calorific value and ash content are of paramount importance so as to improve the combustion process. Furthermore, during the last three decades, there has been an increasing interest in the production of biomass pellets for domestic and industrial use. Alternative feed stocks will need to be sourced to meet the demand for biomass pellets. Investigation for new energy crops that produce high amounts of biomass under low inputs and of high energy efficiency are the main tasks of this field. Therefore, the aim of this study is to assess the biomass yield and the quality characteristics (gross calorific value and ash content) of two perennial energy crops (Cynara cardunculus L. and Panicum virgatum L.) growing in a typical soil (Fluventic Xerochrept) of the main agricultural land of central Greece. The comparison for both cultivated crops was made in order to show the results during their 8th growing year. The examined factors were the irrigation (two levels: irrigated and rainfed) and the nitrogen fertilization (two levels: 0 and 80 kg N ha-1 ) as well as their effect on the dry biomass yield and the gross calorific value. It was found that higher dry biomass yield was produced from cardoon (21.3 vs. 14.23 t ha-1 ), while the higher average gross calorific value was observed for switchgrass biomass (17.31 vs. 15.65 Mj kg-1 ). Finally, multiplying the dry biomass yield (t ha-1 ) with the gross calorific value (Mj kg-1 ) it was found that 334 and 245 Gj ha-1 from a cardoon and a switchgrass cultivation could be produced, respectively. Cardoon has better results than switchgrass probably due to the fact that switchgrass is growing from March till October; while cardoon’s growing period is from October to June and in such areas precipitation is in shortage during summer months. Both crops could achieve high amounts of energy per hectare and thus their introduction in future land use systems, for an environmentally friendly energy production should be seriously taken into consideration

Sorghum dry biomass yield for solid bio-fuel production affected by different N-fertilization rates

The objective of this study was to examine the effect on the dry biomass yield of two dfferent sorghum hybrids (H1 and H2) under five different N-fertilization levels (0, 70, 140, 210 and 280 kg ha-1 ) in a soil which was formed by lacustrine deposits of Karla Lake and is characterized from the downward movement of calcium carbonate from the surface horizons due to leaching (Fluventic Xerochrept) during 2017. The results demonstrated a significant effect (P < 0.05) of fertilization only for one hybrid. Biomass yield ranged from 22.2 to 37.5 t ha−1. For both hybrids, sorghum accumulated a high amount of biomass in stems. Dry stem/total biomass ratio was rather constant throughout the different fertilization treatments achieving 81.6 and 77.5% for the first (H1) and the second hybrid (H2), respectively. The second hybrid (H2) had a higher percentage of leaf biomass (20.1 vs. 13.8%) than the first (H1), but lagged behind in seed production (2.4 vs. 4.6%). Biomass dry matter partitioning and total dry weight are important selection criteria for energy crops, due to different gross calorific value and ash content but also because of the different economic importance they may have e.g. the seed is also used as animal feed. The above high biomass yields of sorghum, confirming the high potential of this crop, should be taken into serious consideration regarding land use planning, but further investigation for the gross calorific value and the ash content is needed as well as biomass characteristics that are quite important in case to improve the combustion process

Effect of Different Tillage Practices on Sunflower (Helianthus annuus) Cultivation in a Crop Rotation System with Intercropping Triticosecale-Pisum sativum

The objective of this work was to investigate the effect of different soil tillage practices on sunflower cultivation in a rotation system with intercropping of Triticosecale-Pisum sativum. For this purpose, a two-year experimental field with a 5% slope was established in central Greece. There were four treatments with three replications each. The treatments were as follows: (a) no tillage planting parallel to the contour (NTC-PAC), (b) conventional tillage planting parallel to the contour (CTC-PAC), (c) no tillage planting perpendicular to the contour (NTC-PEC), and (d) conventional tillage planting perpendicular to the contour (CTC-PEC). During the experiment, the plant height, leaf area index, specific leaf area, plants’ total nitrogen, and plants’ proteins were measured. According to the results, the plant height ranged from 64.9 (CTC-PAC) to 85.2 cm (NTC-PEC) for the first year and between 66.5–86.5 cm in for the CTC-PAC and NTC-PEC treatments in the second year. Furthermore, the leaf area index (LAI) and specific leaf area (SLA), plants’ total nitrogen and protein content and N-uptake were affected positively by the no tillage practice. To conclude, sunflower is a promising crop in a rotation system intercropping Triticosecale-Pisum sativum, cultivated under rainfed sloping conditions. © 2022 by the authors

Effects of environmental factors on herbaceous plant diversity in an organic cultivation of sage (Salvia officinalis l.) in a typical mediterranean climate

Sage (Salvia officinalis L.) is a perennial aromatic-medicinal plant that is commonly cultivated for pharmaceutical uses through the Mediterranean basin. The purpose of this study was to examine the herbaceous plant diversity (plant species richness), composition and their utilization as well as the relationships between herbaceous plant species richness and driving factors (e.g. soil pH, organic matter, temperature, minerals etc) in the organic cultivation of Sage in central Greece. The results showed that the most frequently occurring species were: Papaver rhoeas L., Chenopodium album L., Fumaria officinalis L. and Urtica dioica L. Our data suggested that these plants constitute important soil indicators which could be used to monitor the state of soils along with assessing the role of soil in environmental interactions. According to Principal Component Analysis (PCA), herbaceous plant species richness was positively correlated to soil organic matter, temperature and moisture, P and K in the organic cultivation of Sage. The results of this study highlight the ecological value of the organic sage cultivation and how it can be a useful tool for the ecosystem’s environmental protection, the wider scientific community and the general public during the current economic crisis. © 2020, University of Montenegro. All rights reserved

Comparison of two perennial energy crops for biomass production at the end of their life cycle

Nowadays fossil fuels are decreasing, causing the world's interest in renewable energy sources to rapidly grow. One of the most interesting renewable and ecologically pure fuels is biomass, which is considered to be carbon neutral. Biomass is a promising source of energy, as it can be used directly as an energy resource. Its quality characteristics such as gross calorific value and ash content are of paramount importance so as to improve the combustion process. Furthermore, during the last three decades, there has been an increasing interest in the production of biomass pellets for domestic and industrial use. Alternative feed stocks will need to be sourced to meet the demand for biomass pellets. Investigation for new energy crops that produce high amounts of biomass under low inputs and of high energy efficiency are the main tasks of this field. Therefore, the aim of this study is to assess the biomass yield and the quality characteristics (gross calorific value and ash content) of two perennial energy crops (Cynara cardunculus L. and Panicum virgatum L.) growing in a typical soil (Fluventic Xerochrept) of the main agricultural land of central Greece. The comparison for both cultivated crops was made in order to show the results during their 8th growing year. The examined factors were the irrigation (two levels: irrigated and rainfed) and the nitrogen fertilization (two levels: 0 and 80 kg N ha-1) as well as their effect on the dry biomass yield and the gross calorific value. It was found that higher dry biomass yield was produced from cardoon (21.3 vs. 14.23 t ha-1), while the higher average gross calorific value was observed for switchgrass biomass (17.31 vs. 15.65 Mj kg-1). Finally, multiplying the dry biomass yield (t ha-1) with the gross calorific value (Mj kg-1) it was found that 334 and 245 Gj ha-1 from a cardoon and a switchgrass cultivation could be produced, respectively. Cardoon has better results than switchgrass probably due to the fact that switchgrass is growing from March till October; while cardoon’s growing period is from October to June and in such areas precipitation is in shortage during summer months. Both crops could achieve high amounts of energy per hectare and thus their introduction in future land use systems, for an environmentally friendly energy production should be seriously taken into consideration. © 2020, Eesti Pollumajandusulikool. All rights reserved

Sorghum dry biomass yield for solid bio-fuel production affected by different N-fertilization rates

The objective of this study was to examine the effect on the dry biomass yield of two dfferent sorghum hybrids (H1 and H2) under five different N-fertilization levels (0, 70, 140, 210 and 280 kg ha-1) in a soil which was formed by lacustrine deposits of Karla Lake and is characterized from the downward movement of calcium carbonate from the surface horizons due to leaching (Fluventic Xerochrept) during 2017. The results demonstrated a significant effect (P &lt; 0.05) of fertilization only for one hybrid. Biomass yield ranged from 22.2 to 37.5 t ha−1. For both hybrids, sorghum accumulated a high amount of biomass in stems. Dry stem/total biomass ratio was rather constant throughout the different fertilization treatments achieving 81.6 and 77.5% for the first (H1) and the second hybrid (H2), respectively. The second hybrid (H2) had a higher percentage of leaf biomass (20.1 vs. 13.8%) than the first (H1), but lagged behind in seed production (2.4 vs. 4.6%). Biomass dry matter partitioning and total dry weight are important selection criteria for energy crops, due to different gross calorific value and ash content but also because of the different economic importance they may have e.g. the seed is also used as animal feed. The above high biomass yields of sorghum, confirming the high potential of this crop, should be taken into serious consideration regarding land use planning, but further investigation for the gross calorific value and the ash content is needed as well as biomass characteristics that are quite important in case to improve the combustion process. © 2020, Eesti Pollumajandusulikool. All rights reserved

Nitrogen fertilization effect on biomass yield of six different sorghum bicolor varieties

Sorghum belongs to the Poaceae family and it is used for its high biomass production. A field experiment was conducted using a factorial split-plot design with three replicates and twenty-four plots per replication. The main factor was the different varieties (V1: Buffalo grain, V2: Elite, V3: Big Kahuna, V4: 25K1009, V5: 4264 and V6: 5D61) and the sub-factor the different nitrogen fertilization levels (N1: 0, N2: 80, N3: 160 and N4: 240 kg ha-1, using urinary ammonia 40-0-0). In the case of fresh biomass weight, the variety "25K1009" produced the higher yield, followed by "Big Kahuna" and "Elite" with 66.9, 65.27 and 63.03 t ha-1 respectively, which are statistically significantly higher compared to the yield produced from the other three varieties. The same was also found in the case of the dry biomass weight. The increase in the fresh biomass weight was higher between the higher n-application (160 and 240 kg N ha-1) reaching the 9 t ha-1. Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0)

Determination of heavy metals in the territory of contaminated areas of Greece and their restoration through hyperaccumulators

Phytoremediation is an effective technique for the processing of contaminated soil and for sequestering environmental contaminants such as heavy metals. This kind of pollution is ubiquitous in mines and similar excavation sites. This mini-review aims to provide an overview of the alternative forms of restoring contaminated soils (phytoremediation) highlighting the areas of Kozani (Agios Dimitrios) and Chalkidiki (Stratoni) in Greece characterized by exorbitant metallurgical activities. Firstly, a literature search in databases such as ScienceDirect, SciFinder, PubMed, Google Scholar, and Scopus was conducted, using the following keywords to identify relevant articles: “utilization”, “plants”, “phytoremediation”, “sustainability”, “environment”, and “restoration”. Two case studies have subsequently been chosen in Northern Greece, one characterized by metal mining (Pb, Zn, Ag) and hot summer Mediterranean climate and another one involving lignite mining and concomitant Cr, Zn, Cu, and Ni pollution under subtropical climate. Based on the literature search some possible, non-invasive plant species were proposed, focusing on the most efficient hyperaccumulators. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH, DE part of Springer Nature