Energy crops are well-known for their capabilities to mitigate greenhouse gas emissions and increase soil carbon stocks. Mitigation measures are required to face climate change and sustain marginal farmland and communities in crop production. Crops with high environmental adaptability and yields, such as Arundo donax (giant reed), represent a chance to improve the income of marginal farmland, making areas, which are not suitable for food crop production, once again productive.
By doing so, three of the seventeen Sustainable Developement Goals of the United Nations would be met, namely food security and sustainable agriculture, reliable, sustaianble and modern energy and actions to combat climate change and its impacts. In this article the response of Arundo donax on marginal farmland and expected farm incomes under climate change (2021-2050) are presented, based on a case study, carried out in Italy, in 2017.
How could Arundo donax be utilised on marginal farmland?
As an increasing attention is being paid to the food vs. fuel dilemma, competition between food crops and energy crops for use of land and natural resources became a huge issue. In some countries, the agro-energy has entailed the use of forage crops (maize) as feedstock in the biofuel supply chain, leading to an increase in their market value, as well as to the increase of food prices.
Apart from the above mentioned issue, a solution is needed for making small scale and marginal farming communities more resilient to climate change, developing adaptation to natural hazards.
In the Mediterranean region, for example, Arundo donax, a fast-growing perennial crop, is a suitable species with high environmental benefits. It reproduces only vegetatively, through rhizomes, as it has no fertile seeds. However, with our micropropagation technology, which is a unique, peerless, state of the art technology, based on sustainable embryogenetic and somatogenetic tissue culture, we are able to develop virus free, genetically stable, vigorous, homogenous bare root plantlets on an industrial scale. Giant reed is able to produce large amounts of biomass in conditions typically found on marginal farmland, such as chemically and physically degraded soils.
Incomes obtained from this crops can be determined by direct selling of giant reed biomass as feedstock for green energy (woodchip or chopped forage), or by means of the biogas or biofuel gained. It must be pointed out, that giant reed is grown with low-input systems (without irrigation or with wastewater irrigation, without or with compost fertilization), therefore it is thought of as the most efficient crop for greenhouse gas reduction. Arundo donax preserves and improves the soil carbon stock, reduces the need for soil tillage and prevent soil erosion. Most importantly, it allows savings in fossil fuel resources and at the same time decreasing CO2 emissions in the atmosphere.
Arundo donax: marginal farmland experiment, crop monitoring and results
The long-term study, on which this article is based, took place in Italy, between 2008-2017. The marginal farmland soil ranged from clay-loam to sandy clay, without gravel. Plants were grown under low-input systems.
According to the results, giant reed chip production rose from 4.9 to 48.0 tonnes/hectare in the first three years. Interestingly, Arundo donax biomass yield in this low-input experiment agreed with those in Testa et al. (2016), where giant reed plants were grown in ideal circumstances, meaning proper irrigation and fertilization.
Arundo donax proved well adapted to the different water availability conditions in 2012 and 2013, as in 2012 there was +24% of rainfall during the cropping season, compared to 2013. In spite of these factors, the final yield did not show significant difference.
The assumed future scenario about the climate from 2021 predicts a warmer and dryer weather during the growth period of giant reed (from March to December). In the stimulated future scenario, sprouting was determined in early March (first 20 days) with a harvest at the end of November. According to the yields in the experiment it can be hypothesized that no yield decreases occured in the later years, namely in year nine.
As for income calculation, the average yearly gross margin of chip production was almost twice as much than that of chopped biomass: 636 euros versus 339 euros per hectare. It was concluded that giant reed chip production would be the most profitable option for marginal farmlands, yielding a gross margin 50% lower than ordinary, high-input maize cultivation under similar circumstances. Although it may appear unrewarding, one has to bear in mind that Arundo production in this study was done on marginal land with low input cultivation, whereas corn was treated with more care, which it does demand. Moreover, with the boundaries of land usage, scarce arable soils and stricter regulations on food crop usage for energy production, the ideal cultivation efforts on suitable lands will be unlikely in the future. Thus, when putting the Arundo yield on marginal farmland into perspective, this achievement is outstanding and it foreshadows the steps agriculture and energy production is taking.
In conclusion, bioenergy crops do not necessarily compete with food crops. On the contrary, having estimated profitability, it is very close to major food crops, such as maize. It is now confirmed that growing giant reed on marginal farmland (unsuitable for food crops) can support the resilience of farming communities.
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