Italian scientists have studied the benefits of unpretentious Jerusalem artichoke. It turns out that this is a kind of indispensable culture for the production of renewable energy.
In his scientific work, a team of Italian scientists from the Faculty of Agricultural and Forest Sciences (DAFNE), University of Tushia, explains why Jerusalem artichoke is so good and important.
Recently, biofuels have become a strategic direction for reducing emissions from vehicles. But at the same time, biofuel production is increasingly mentioned in the context of its negative consequences, since the main crops for these purposes, such as, for example, rapeseed, wheat or soybeans, require high-intensity agricultural practices and fertile soils, the authors note. (Biofuels are carbon-based energy sources derived from biological material).
While the EU Commission recently classified biofuels as a product with a low level of indirect changes in land use, obtained from crops grown on marginal lands with little resource use.
For this reason, only a few crops in Europe can achieve high yields with these requirements.
Jerusalem artichoke is a feed for agricultural animals, biofuel and even fruit beer.
From this point of view, Jerusalem artichoke (Helianthus tuberosus L.), of course, is a species worthy of attention, since it possesses all the attributes necessary to achieve the objectives of the updated EU Renewable Energy Directive (RED II).
Jerusalem artichoke is widely adapted to a diverse and often low-yielding environment for other crops, and has high adaptability.
It is a multi-purpose crop used for human consumption (directly in tubers or for sweeteners), for pharmaceutical purposes, for the production of biomass and bioenergy (bioethanol and biogas).
In addition, similar to other plants Asteraceae, such as chicory and safflower, Jerusalem artichoke has potential as a feed crop.
Interestingly, thanks to innovations in the brewing industry, tubers are used to produce sweet and fruit beer.
The stems and tubers of Jerusalem artichoke are characterized by a high inulin content with the potential to produce ethanol for use as biofuel.
In particular, organic compounds (such as inulin and cellulose) and sugars are processed to produce ethanol by fermentation and distillation.
Over the past 20 years, significant work has been done to improve the conversion of biomass to fuel. However, first-generation biofuels (bioethanol and biodiesel derived from food crops) are extracted from only a few crops with different efficiencies in converting solar radiation to chemical energy (biomass).
In particular, biofuel feedstocks are mainly rapeseed, oil palm and soybeans for biodiesel; and sugarcane, corn, sugar beets, and sweet sorghum for bioethanol.
In addition, not all biomass is suitable for collection (i.e., the biomass of vegetation under the ground usually remains in the soil), so net carbon sequestration is reduced and processing inefficiency is increased.
For these reasons, plant species for next-generation biofuel production systems are expected to overcome some of these limitations, especially if they have productive underground biomass (i.e. roots or tubers).
In addition, since intensive agricultural land use has already been introduced in most regions of the world, bioenergy crops must be environmentally sustainable in order to avoid additional burden on agricultural biodiversity, soil and water resources.
Scientists are looking for bioenergy crops of the future
Research is being conducted in the direction of systems for generating energy from a new generation of biofuels with less environmental impact, greater productivity and greater return on investment, and also taking into account reduced competition for land use with food and feed crops.
Lignocellulosic biomass from isolated bioenergy crops and agricultural waste is considered a sustainable resource for bioenergy production, but hydrolysis using cellulolytic enzymes is a more laborious and expensive method than using starch or molasses biomass.
In this regard, among the most attractive biofuel systems of the next generation are interesting algae and Jerusalem artichoke, which produces tuber, which can also be grown and harvested using the existing infrastructure and mechanisms used for similar crops (tuberous plants).
Why Jerusalem artichoke really needs Europe
Characteristics that make Jerusalem artichoke a worthy energy crop include: fast growth, high carbohydrate content, the corresponding total dry matter per unit area, the ability to use nutrient-rich wastewater, pathogen resistance / tolerance, the ability to grow easily with minimal external production costs and on marginal lands.
This last aspect promises to be key to the future of biofuels in Europe.
As provided for by the revised Renewable Energy Directive (RED) adopted by the European Parliament and the Council (Directive 2018/2001), the EU Commission recently adopted a delegated act setting out criteria for determining important indirect land-use changes.
ILUC is a hazardous feedstock with significant indirect expansion of production space on land with high carbon reserves, and certification of low risk ILUC biofuels, biofluids and biomass fuels.
Certification may be granted if the fuel meets the following cumulative criteria:
(i) meeting sustainability criteria, which means that raw materials can only be grown on unused land that is not rich in carbon;
(ii) the use of additional raw materials as a result of measures to increase productivity on already used land or growing crops on areas that were not previously used for cultivation of crops (unused land), provided that the land was abandoned or severely degraded, or the crop was grown by a smallholder;
(iii) compelling evidence that the previous two criteria are met.
Obviously, in accordance with the requirements of the Directive, such additional raw materials must meet the requirements for the production of low-risk fuels only if they are obtained in a sustainable manner.
For this reason, Jerusalem artichoke is a promising candidate who can easily replace crops such as corn and sugar beets.
Rapidly growing biomass for biofuels
The growth kinetics of plant parts indicates its ability to produce optimal crops in Europe.
Two-thirds to three-quarters of the dry matter of the air is represented by stems and branches, while leaves and flowers contain a lower percentage. The proportion of the distribution of dry weight is highly dependent on many factors: variety, planting time, climatic conditions and growth conditions.
More than 50% of the total mass of plants is in the stem.
There are two phases to stem growth. During the first five months, a linear increase in the height and weight of the stem is observed. After this period, the height of the stem reaches its maximum and remains unchanged, and its weight decreases.
The maximum height and weight of the plant varies depending on environmental conditions and genotype. In early varieties, the final height reaches 140 cm, while in later varieties, the final height is about 280 cm.
Consequently, at the end of the growing season, the amount of dry matter in the stems of late varieties was approximately two times higher than in the early varieties. Thus, the total biomass of late ripening varieties is higher than that of early ripening varieties. Modeling showed that in later varieties a longer preservation of the optimal leaf area allows better absorption of dry matter.
Hassle-free Jerusalem artichoke
Due to its resistance to drought and salinization, Jerusalem artichoke can be cultivated in soils unsuitable for other root crops and tubers. It grows well in soils with a pH of 4,4 to 8,6.
If heavy clay and hydromorphic soils can complicate the harvesting of tubers, in such conditions Jerusalem artichoke can be cultivated to produce stems.
In general, the yield, size and shape of tubers depend on the type of soil. While lightweight loamy soils produce large tubers, heavy soils provide good drought yields due to the better moisture-retaining properties of clay soils.
As for the temperature of cultivation, for most varieties of Jerusalem artichoke, a vegetation period of at least 125 frost-free days is required.
In general, cultivation temperatures in the range of 6–26 ° C are required to obtain the optimum yield.
The plant has moderate resistance to frost. During early growth, the crop tolerates temperatures up to -6 ° C, although low temperatures cause leaf chlorosis. As for the autumn harvest, frosts from -2,8 ° C to -8,4 ° C trigger the mechanism of tubers acclimatization to the cold. This improves their taste due to the conversion of inulin to fructose.
In the natural environment, some organisms (microorganisms, insects and mammals) interact with Jerusalem artichoke plants, including six different families of bees and bumblebees.
Many phytophages and microorganisms have been recorded on Jerusalem artichoke, but very many of them can seriously damage the culture.
In general, the aerial part of the plant is less susceptible to disease, while tubers during late growth and storage are more susceptible. The most harmful pathogens are Sclerotinia sclerotiorum and Sclerotinia rolfsii, which cause rot.
The former is promoted by excessive nitrogen fertilizer, low soil pH or hydromorphic soils, and the latter by moisture combined with high temperatures.
Also rust caused Puccinia helianthiand powdery mildew caused by Erisyphe chicoracearum, affect Jerusalem artichoke, but they are not able to limit the yield, like leaf spot due to Alternaria helianthi.
When storing tubers, especially when they are damaged during harvesting, diseases caused by Botrytis cinerea, Rhizopus nigricans, Fusarium и Pennicillum spp.. However, freezing procedures effectively control these diseases.
As for insects, this is mainly aphids, but their effect is negligible.
The plant is hardy and strong, so Jerusalem artichoke can become a very competitive weed on its own. As for other fast-growing weeds, the fight against them is necessary only during sowing until the canopy closes. Both chemical and mechanical (top dressing, loosening, etc.) weeding can be used.
Once Jerusalem artichoke has settled in the field, it is quite difficult to remove, since tubers or parts of them remain in the ground, wintering well in the soil.
Selection of Jerusalem artichoke
Valuable biological and biochemical properties of Jerusalem artichoke are the basis of its universal use in the food and industrial industries, which necessitates the genetic improvement of the crop.
The main focus in the selection is on the yield of tubers and the inulin content for food and feed, and recently, the focus has been on building up biomass for biofuel production.
However, due to the traditionally limited use of Jerusalem artichoke, to date, quite little progress has been made in breeding. Investments in breeding developments are also volatile and depend on the demand of industrialists in each country.
The renewed interest in Jerusalem artichoke in the 1970s and 1980s, associated with the energy crisis and food shortages, encouraged more coordinated and intensive action to develop new varieties to meet emerging needs.
Since then, a significant expansion of cultivated areas has been recorded, especially in the last decade in Asian countries.
Given the current climate change, the need to find new sustainable energy sources and the reduction of areas intended for food production, investments in the selection of Jerusalem artichoke seem to be largely justified.
USA may also be interesting Jerusalem artichoke
To date, the most common crops used to produce ethanol are corn, sugarcane, sweet sorghum and sugar beets. However, these species depend on fertile agricultural land and, as a rule, need significant external resources (i.e. water, pesticides, fertilizers) to achieve high yields.
The United States and Brazil are the world's largest producers of bioethanol fuel. They accounted for about 84% of global bioethanol production in 2018.
Cereals and sugarcane are the dominant raw materials for ethanol production in these countries.
Ethanol production in 2027 is expected to account for 15 and 18% of world corn and sugarcane production.
The United States, as Europe, mainly uses corn and wheat starch to produce bioethanol, while sugar cane is processed in Brazil. In general, sugar cane has a higher ethanol yield than corn and other crops such as Jerusalem artichoke.
However, sugarcane is ideal in tropical and subtropical, but not in temperate climates. Therefore, tominabur may take its place next to corn in the production of American ethanol.