Faculty of Science and Forestry
Lignocellulosic crop production in arable lands in Northern Europe:
review on production, area and environmental effects
Seikh Mahbub Sharif
MASTER’S THESIS CROSS BORDER UNIVERSITY
JOENSUU 2020
Sharif, Seikh Mahbub. 2020. Lignocellulosic crop production in arable lands in Northern Europe: review on production, area and environmental effects. University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences. Master’s thesis in Forest Science specialization in Cross-Border University (CBU), European Forestry, 35 page.
ABSTRACT
Bioenergy crop production has been increasing worldwide during recent years, while Sweden is a leading country for bioenergy crop production. After the 1970s world's fossil fuel crisis and global concern about climate change in the 1990s, Sweden has given special focuses on the alternative sources of energy. From this perspective, the country has introduced many initiatives to produce bioenergy crops in arable lands. And to find out the plantations in arable land, a geostatistical kernel-based analysis has been used in this study. It is a non-parametric method mainly use to estimate the spatial distribution based on observed events. After including two factors, frequency of the plantations and density we used kernel function with bi-variate distribution curve. When variables have analysed as the Universal Transverse Mercator (UTM) coordinating the willow plantations. On view of environmental perspective, using of arable lands for bioenergy crop production may have some effects on the country. The study has focused also on how environmental impacts may minimize energy crop production in Sweden when the it has excluded the comparison of GHGs emissions of fossil fuels rather than the land- use changes in Sweden. The overall discussion is on the country basis, for the environmental benefits, it has divided into four categories like air, water, soil, and biodiversity. After comprising with the traditional agriculture food crop cultivation in arable land, bioenergy crops cultivation is more beneficial because it reduces carbon dioxide (CO2) and nitrous oxide emissions (N2O) from the organic soils, the most important GHGs. The reinstallation of carbon happens in the arable land because of the energy crop cultivation. Also, it increases the soil fertility and decreases the wind and water erosion of soils. To purify the municipal wastewater bioenergy crops e.g. Salix and reed canary grass may use. Even the heavy metals effects, nutrient leaching, and overuse effects of pesticides also be possible to reduce by the bioenergy crop cultivation in arable lands. Without contaminating the genetic species for a long term in the same arable land, bioenergy crops cultivation, especially the short rotation forest, has positive effects on biodiversity also.
Keywords: Bioenergy crops, arable lands of Sweden, environmental effects
FORWORD
This thesis work is for the accomplishment of the Cross-Border University (CBU) MSc degree program in Forestry, which is organized by the School of Forest Science, University of Eastern Finland. Accordingly, I would like to show my appreciation to the university to help me with the completion of my desired goal.
First and foremost, I want to extend my gratitude to my supervisor, Adj. Prof Blas Mola- Yudego, University of Eastern Finland, School of Forest Science, for his advice and guidance on my thesis work. His outstanding research knowledge and teaching approach let me know how to work with maintaining a higher standard. His inspirational behavior helps me a lot to pursue every step of my thesis work very smoothly. Also, I would like to thank my co- supervisor, MS Xiaoqian Xu, for her valuable guidelines, helpful suggestions. Part of the analyses were driven by her. And I feel very blessed and pleasant being a part of this research group because I had many wonderful colleagues with their support and friendship. I wish all of you the best luck in your future endeavors.
Finally, I would like to express my most enormous thanks to my parents; they always gave me their unconditional love and patience.
Table of Contents
1. Introduction………..1
1.1. General context………..1
1.2. Development of biomass production of Sweden……….1
1.3. Land use strategy of Sweden for energy crop production……….2
1.4. Objectives………...4
2. Material and methods………5
2.1. Study area………...5
2.2 Data sources……….5
2.3 Methods………6
3. Results and Discussion………..8
3.1. Cultivation of fast-growing crops in Sweden………...8
3.2. Review of environmental effects………..15
4. Conclusions………...22
5. References……….23
1. Introduction
1.1 General context
From recent topics, climate change is a critical issue. To reduce the climate change effect, we should decrease the Green House Gas (GHGs) emission. For this perspective, bioenergy can play an important role to reduce greenhouse gas emissions. About 9855 million metric tons of carbon has released during 2014 when 75% has emitted from fossil fuel burning and production of cement. Also, 18.5% or 1823 million metric tons of carbon has released only for the combustion of natural gases. (Boden et al., 2017). But the 97-98% of GHG emissions could be decreased after using the wood fuel. (Ladanai et al., 2010). According to the renewable energy directive of EU, the member of European Union states should reduce the fossil fuel burning, and they should depend on the renewable sources at least for 20% of total energy demands during 2020.
All EU members also should ensure that 10% of energy would come from renewable sources for transportation. For this perspective, every member state of the EU is very concerned about fossil fuel burning and trying to use more biomass fuel or bioenergy. Among them, Sweden is the leading country for biomass production. Sweden has fulfilled 49% of the target that has given by the European Union and in the highest position from all other European countries.
(European Union, 2009). To get this success, Sweden has taken some strategy to produce energy from various renewable energy sources like wind, wave, solar, biomass, ethanol, body heat, nuclear reactions, etc. (Sweden.se, 2019). But the fuel from biomass sources becoming more popular and has doubled from the last 30 years. (Björheden, 2006). Most of the cases this biomass has come from the forest and forest products and many other short rotation plants. So Sweden needs to manage the land resource properly because the production of biomass may affect other agricultural activities.
1.2 Development of biomass production of Sweden
Biomass production in Sweden has started after the 1970s oil crisis in the world. After this oil crisis, Sweden has emphasized on the alternative energy sources. Since then, the energy policy of Sweden has started to think about biomass production as an alternative source of fuel.
(Jansson, 2016). In the beginning, the sources of biomass production related to forest products and forest residues. But after 1990, global warming and greenhouse gas emission added a new dimension for the energy production policy in Sweden. The country started to introduce the tax systems on CO2 emissions. (Henrik & Jenny, 2018). After taxing on CO2 emissions, biomass
production has become more prevalent in Sweden, and the farmer has started to cultivate the bioenergy crops economically.
From the last two decades (1980-2002) using biomass in Sweden has increased by 88%. Only in 2002, 14% of total energy has come from the bioenergy. (Swedish Energy Agency, 2003).
But in 2015, it has increased 134 TWh means 26 percent of total supply has come from the biofuel. (Swedish Energy Agency, 2017). It has happened because of the conflict between Swedish energy policy and the environmental policy. Sweden has emphasized for biomass production to reduce greenhouse gas emissions. (Johansson, 2004).
From 1980-2016, the total energy supply of Sweden was almost the same as 550-600 TWh per year. While in 2016, the total energy supply was 564 TWh and consumption was 375 TWh.
While the energy source from biofuels in the second position (139 TWh) after nuclear fuels (178 TWh). Sweden has divided the energy consumption into three different sectors in 2016 like i) industrial sector 142 TWh ii) Residential and service sector 146 TWh iii) Transport sector 87 TWh. (Markus, 2018).
1.3 Land use strategy of Sweden for energy crop production
For land management, Sweden is using three levels of governance. At the national level, the country divided into 21 counties and 290 municipalities. Forasmuch this country is one of the most sparsely populated countries in the world, where per capita of land consumption is very low, and the country containing only 1.4% developed land. As the country has enough land for the dwellers, so it has not any specific spatial plan for the land management at national level.
However, after the thinking of energy crops production, it has taken some sustainable land-use strategy at the regional level. (OECD, 2017). It has 28 133 000 ha forest land when the total land of its 40 731 117 ha. In proportion, it is about 69% of the entire land. Without the forest land Sweden has lakes, shallow soils, wetlands, grasslands, bare lands, and mountains, etc.
(SCB, 2019).
The country has 8% of agricultural land from the total land which has included in the arable land. In-ground level the useable land of Sweden has divided into four categories. From the following figure, we can see that the amount of arable land is decreasing from the past year when the productive forest land is increasing gradually (SCB, 2015).
Also, the country divided into eight vegetation zone. Where most of the area dominated by the boreal zone and covered by the slow-growing coniferous forest. Because of the northern location in earth the country has low productive capacity with nutrient-deficient soils, but the Southern part like the Nemoral and Boreo-Nemoral are most productive land than the Northern Boreal parts. (KSLA, 2009).
For the economic evaluations and environmental security, using the land resource sustainably are becoming more critical and challenging day by day because the confusion about bio-energy crop production and food production may controversy with each other. But the cultivation of energy crop by proper mapping in the arable land would be more effective as it is possible to produce as a by-product from the food crops. Also, energy crop production is thinking more cost-effective than agricultural crop production by the farmer. Because of giving subsidies and reducing the tax on energy crop, farmers becoming more interested in using their land for energy crop production. That is helping to fulfill Sweden's strategy about energy crop production in arable land. (Paulrud, 2007).
In 2014, only 30% of primary energy supplies had come from fossil fuels in Sweden when more than 52% of energy sources were from renewable sources. For this reason, the country has the lowest amount of greenhouse gas emissions per capita. In 2020, greenhouse gas emissions would be decreased at 40%, and by 2050 the country would not emit any greenhouse gas emissions. As this purpose, using bioenergy has a significant contribution to this country. In 2014, the country got fifth and sixth rank respectively for bioethanol and biodiesel consumption in Europe. For biogas and biomethane consumption, Sweden was in the first rank. Even for the district heating purposes bioenergy contributed 71% of the total energy. (Cruciani, 2016).
Though the major part of the bioenergy comes from the forest and forest products, the agriculture sector is growing abruptly for the bioenergy production by providing various byproduct and direct cultivation of the energy crops. So, the creation of foods and energy crop production in Swedish arable land is making the most competitive way of land use and contributing to change the land. (Berndes & Magnusson, 2006). In 2011, Sweden had about 2.7 million ha of arable land where about 146,000 ha land was fallow; it means that around 6.7%
arable land was useless. Mostly those fallow lands were covered by meadows and grazing land.
Near to half a million ha was classified as grazing or meadow land when the total agricultural land was 3 million ha in 2011. (SJV, 2012). Though the grazing land and meadows have some positive environmental effect because it protects biodiversity and wildlife. (Från, 1992). But the Swedish government has the plan to convert some of the fallow lands for the bioenergy crop
production. So, from 2008 to 2011 more than 10% (from 514,000 to 447,000 ha) of fallow land had decreased. (SJV, 2012).
1.4 Objectives
Many drivers are related to the land-use changes that we have understood from the above discussion. Here this study has focused on a review of the land-use change for bioenergy crops production. The term is very critical from several views. For example, if the arable land use for bioenergy crop production rather than agricultural production, there may have some effect on annual food production, which has some socio-economic effect. Then the government has a plan to produce bioenergy crops and giving incentives or benefits to the energy farmer that is making more enthusiastic to the farmer to convert them from traditional farming to bioenergy crop cultivation which also has some socio-economic effects in Sweden. Also, from the ecological and environmental perspective, if the abandoned land (like meadow, grazing land, etc.) of arable lands are converted as the energy crop production there has ecological and environmental values connected with those abandoned land. But the bioenergy crop produces less GHGs than the traditional agriculture production even they may reduce the pressure of conventional fossil fuel burning that has positive effects on the environment, economy and society also.
The research has attempted to analyze the following question shortly:
i) What are the main energy lignocellulosic crops in the country?
ii) Where are those energy crops established and planted?
iii) What are the potential effects of these crops on the environment?
2. Material and methods
2.1 Study area
Sweden is mainly dominated by grain cultivation. For the agricultural purposes in the arable land, it has divided into two significant regions, like the Northern part and the Southern part.
Reed canary grass is more prevalent on the Northern side because the cold climatic condition is not suitable for other salix cultivation. (Official Report of the Swedish Government, 1992).
Currently, arable lands are almost equally distributed with perennial forage and annual food crop cultivation. And the proportion is about 40% and 60% respectively. (Statistics Sweden, 1995). For the environmental aspects, energy crop cultivation impacts depend on the different local conditions of the different regions of Sweden. Where Sweden has divided into 21 municipalities. (OECD, 2017). Environmental impact is an extended term for discussion. But in this context for the bioenergy crop cultivation in arable land, we can assume the environmental effects in brief on water, air, soil, and biodiversity (that indicates on flora and fauna). Though effects are very interconnected with each other, but we can recognize them as separately like i) Green House Gas Emissions (GHGs) as the effect on air, (its interconnected with all other effects), ii) wastewater treatment for bioenergy crop cultivation on arable lands as indicates the effect on water, iii) effects on soil by assuming the fertility rate, erosion rate, absorbing rate of heavy metals and way of nutrient leaching, and finally the iv) biodiversity effects.
Here the study has used the data from the previous articles, journals, Statistics of Sweden (SCB), etc. and have reviewed the data to make some correlation to show the effects on environment in the context.
2.2 Data sources
The data for the willow plantations collected from previous papers and from the Land Register of Sweden. In some cases, information about the area which was cultivated by the private owners also included in the map. But in that case, data with lacking information or inconsistent records regarding the ownership were excluded from the calculations. As we know of the prior discussion, Sweden is the leading country for bioenergy crop cultivation in Europe. It cultivates different kinds of bioenergy crops in the whole country. Here the study focused only on the cultivated bioenergy crops in arable land. As the study has used the overlay comparison of Sweden Basic Map based in the Image & Corine Land Cover 2000 (I&CLC, 2000) vector
map for Sweden using a 250 m resolution in Figure 2. The studied duration was from 1986- 2015 when the first year considered as the growing year of willow plantation, and the corresponding year considered as the year of adaptation. For the reed canary grass, a database was compiled from the previous studies, including Landström, S et al. (1996), Lindvall, E., et al (2015), Nilsson, D et al. (2015), Lindvall, E., Gustavsson, A. M., & Palmborg, C. (2012) and Lindvall, E. (2014). Some of the figures presented in those papers were digitized for data extraction.
2.3 Methods
To perform the study, a geostatistic way based on the kernel analysis have applied here, as in Mola-Yudego and Gonzalez-Olabarria, 2010. It is a non-parametric method frequently used to estimate the spatial distribution based on observed events. Where to identify a spatial region, a continuous grid should create, and then all possible specific events of every point have calculated. This calculation happens based on two factors, i. based on the frequency of the plantations, ii. observed events density frequency. For density function, all territory or all points in the grid have calculated as density frequency. Also in the kernel function, here we used standard bi-variate distribution curve, and the variables have analyzed as the Universal Transverse Mercator (UTM) coordinating the willow plantations and the willow growers in the following equations:
Here K(x,y) is density function for point x and y when they coordinate the point xi, and yi inside the studied area of observed willow plantations n. And h is the smoothing parameter that has determined the level of aggregation of the data in the density functions. But there have no widely accepted methods for smoothing factors except the ad hoc choice. Here the parameter calculated by the following equation:
Here n is the number of willow plantations, and x and y variance have standardized as the varx
and vary. Href is the reference value that calibrated the n, varx and vary. The final calculations have done by the kernel variables when the smoothing parameter h is not fixed for the locations.
It means the smoothing factor h, is not adjusted for the lower concentration of plantations in smaller areas. So, the plantations of bordered areas are not over-represented.
Also, the reference value has calculated at some intervals. In equation 2, 40% of the reference values href have applied and compared with the different values of the smoothing parameter h in the final version. Home Range Extension (HRE) package in ArcGIS 9.0 from Centre for Northern Forest Ecosystem Research (CNFER) has used for kernel estimation. And raster maps with standardized isopleths based on percent volume contours (PVC) have measured to analyze the resulting kernel estimation. Percent Volume Contours (PVC) may define as the volumes of utilized distribution to represent a specific percentage of plantations in the possible smallest area. For example, if the map represents 90% of the total area, it means the map contains the lowest density with the highest number or almost the total number of plantations. But if it represents 10%, it means it's indicating the highest density in the core area. Here the resulting maps showed 150×150 grid cell resolution. The geographical kernels were based on ArcMap and R sorftware.
3. Results and Discussion
3.1. Cultivation of fast-growing crops in Sweden
Status of area planted
Cultivation of bioenergy crops in arable land has flourished from the recent few decades because of the worldwide energy crisis and focusing on the sustainable energy sources with less environmental effects. For the cultivation of bioenergy crops in the arable land, we divided the Sweden map into two significant regions, like the Northern part and the Southern part. Reed canary grass is more prevalent in the Northern side because the reed canary grass can grow in cold climatic condition but for willow cultivation, it is not suitable.
In Sweden, about 13 kinds of energy crops are available which are mainly cultivated in arable land as produce to bioenergy. Without energy crops, the country also produces many oil crops.
But here the study has only discussed the estimated cultivation of different fast-growing bioenergy crops, for example, Willow, Poplar, and Hybrid aspen in specific areas in different years, as well as reed canary grass. As we can see in figure 1, the cultivation of willow has started as bioenergy crops in 1985. As the trial part of cultivation, very minimum amounts were cultivated and it was even below 1000 ha. For the hybrid aspen, about 500 ha was cultivated in 2007 but in 2012 it had increased about 980 ha. In the same way, for willow, the total cultivation was about 14000 ha in 2004 but the amount has increased about 8000 ha. So, the proportion indicates that it is increasing in the upcoming years. Also, for poplar, the amount of cultivation land is increasing. At 2000 it was 100 ha but in 2015 it has risen up over 800 ha. Reed canary grass reach to about 800 ha during same period. For this purpose, we can say that the overall cultivated land in hectares is increasing. After setting the all point with cultivated areas, we can estimate how the bioenergy crop cultivation is growing in Sweden that is representing the figure1. Also, as a partial study, we discussed the growth of reed canary grass cultivation based on the previous study with overall environmental outcomes for the cultivation of bioenergy crops and reed canary grass.
Fig 1. Changes in the area planted with lignocellulosic energy crops in Sweden of the main energy crops. Source: 1986-2003 from Mola-Yudego (2008), 2004-2017 from Swedish Land Registry, estimated from the records (Xu and Mola-Yudego, 2020).
Table 1: Some selected studies about the land availability for bioenergy crop production
References Available land Possible year Progress Comments Från
Biobränslekommiss ionen, S. (1992)
Would be 800, 000 ha
In 2005 Not estimated Got attention to
produce an
alternative source of fossil fuels Börjesson et al
(1997).
About 30% of the arable land was distributed for the bioenergy crop production
In 2015 Energy yields
would be 5 to 15%
higher from forestry and 2 to 3% from cultivated energy crops and 1 to 2%
from traditional food crops.
Sweden had divided in to three regions Southern Sweden (latitude 56˚-58˚N);
Central Sweden (58˚-62˚N); and Northern Sweden (62˚-68˚N).
Prade et al. (2007). 88,000 ha abandoned arable land is possible to use for energy crop production and 75,000 ha possible to apply for intermediated crops (the crops do not compete with food crops and use as catch crops)
In 2013 Focused on the
agriculture
residues, grass leys, additional crops, and intermediate crops also may apply for the energy production
Declared 68 TWh potential annual energy from the energy crops.
Det framtida jordbruket (1997), Stigfinnare. (The
553,000 ha In 2021 Not estimated Forest biomass
475,000 ha and energy grasses 75,000 ha
future of agriculture).
Det framtida jordbruket (1997), Vägvinnare. (The future of
agriculture).
458,000 ha In 2021 Not estimated The cultivation of
energy grasses will increase to the whole area with the cereals and other crops.
Det framtida jordbruket (1997), Målbild. (The future of agriculture).
650,000 ha In 2021 Not estimated For energy grasses 266 000 ha and energy forest 384 000 ha.
Kumm, K. I.
(2009)
650,000 ha In 2021 Not estimated But the area for
salix cultivation was unchanged from the last decades, and it is about 15,000 ha.
Herland, E. (2005) 400,000 ha In 2020 Not estimated Salix cultivation 300,000 ha and wheat and others would be 100,000 ha
Geostatitsical analysis of core areas and locations
The following map (figure 2) is showing the location where the bioenergy plantation is abundant. According to the base of the pink color, we can determine where is suitable for willow grown up. The scale is showing the level of high, medium, and low densities places in the maps.
Besides the maps the concentration scale is indicating the concentrations with color for example From the map it is completely clear that for the bioenergy crop cultivation Sothern-East part and the Orebro (Central Sweden) are the best because of the temperature stability and plus temperature. The amount of percentage was from 60% to 80% has indicated 0.6 to 0.8. But the less prominent areas have indicated as the pinkish color. The northern part of Sweden has not included because of the very minimum cultivation or ignorable data on the map.
Figure 2. Areas with concentrations of bioenergy plantations from 1990 to 2015.
To follow up more about reed canary grass and willow cultivation we can notice at figure 3.
Where reed canary grass cultivation has remarked as the blueish color and willow has remarked as the gray color in Sweden. From the figure, we can easily determine that willow is very abundant in the Southern and Central places of Sweden. While for reed canary grass we can see it is abundant in Central and North Eastern parts of Sweden. Due to the extremely cold temperature, the Northern part is not suitable for any kind of cultivation. For the same reason, the North-Eastern part of Sweden is not a good place for the cultivation of any other crops. So it's better to cultivate reed canary grass in this fallow land of Northern part or East-Northern part of Sweden. Because it is economically and environmentally more convenient.
Figure 3. Location of reed canary grass areas compared with willow using kernel methods.
Concerning the sustainable land-use strategy, the study about the changing quantity of arable land and the productive forest area is significant. Even it may change the vegetation-covered zone. For a sustainable land use strategy, the country has divided the land-use change into two categories: I) Indirect land-use change (iLUC) and II) Direct land-use change (dLUC). (Berndes et al., 2013). As the country has a target to produce bioenergy and biofuels, which is giving back up the recent land-use strategy. So, the Swedish government has reduced the tax and has increased the incentives for energy crop cultivation in their farmland. Those systems are affecting the arable land to convert them for bio-energy cultivation even sometimes the target is affecting the non-productive forest area that may turn the forest as increasing of productive forest area. This tax-reducing techniques and incentives option has made the farmer more enthusiastic about producing energy crop (Rosenqvist et al., 2000). And the production of energy crops or energy-related products in traditional agricultural farming land is recognized as the “energy farming” is one of the essential sustainable land-use strategies (Faaij, 2006). As the continuity of this strategy, about 2% of arable land had used for energy crop production in 2008. (Ostwald et al., 2013). This percentage will increase in future. In 2050, about 900 000 hectares may use for energy crops has estimated by the Swedish Board of Agriculture when the Swedish Energy Agency already has claimed that this amount might be possible to get in 2030- 2035. (Kjell, 2017). In 2006, about 1-1.5 TWh had produced by the Swedish agriculture sector (Swedish Government Official Reports, 2007), when the Federation of Swedish Farmers (LRF)
had committed it would increase to about 5 TWh in future. (Jonsson et al., 2011). At the same year in 2006, about 70,000 hectares had used for energy crops cultivation which was 3% of total arable land of 2.7 million hectares. When in Sweden, different kind of energy crops mainly used for various purposes. (Börjesson, 2007). Also, they might use for the same purposes. At least 13 energy crops have used in Sweden. For the production of ethanol, the most significant area about 30,000 hectares were cultivated by the straw (a by-product of cereal). (Ostwald et al., 2013). Besides this, 25,000 hectares were used for the oilseeds cultivation to produce rapeseed methyl ester (RME), 14,000 hectares for Salix cultivation to provide energy for different purposes and about 6000 hectares were used for oat cultivations to produce heat.
(Börjesson, 2007). The other crops like hybrid aspen, poplar, reed canary grass, ley crops, grass, corn, sugar beets and Hemp (a new energy crop) were usually cultivated in inconsiderable amount like about 4900 hectares. (Ostwald et al., 2013).
Yields and productivity
Yield data for bioenergy production was adopted especially from Southern and central Sweden except for reed canary grass. The data was collected by the land registry and some from the previous published international journals.
Concerning reed canary grass, the average of the database extracted from the literature show an average of 7.51 odt / ha yr (st =1.88), which was largely based on experiments (result calculated from N=177 digitised yield results from the papers included). Based on the data analysed, the average yield for the top 10 % of the records were 10.7 odt / ha yr, and for the top 5%, 11.2 odt / ha yr. A similar study from willow plantations based on trials (Mola-Yudego et al, 2014) found that the top 10 % of the records were 13.7 odt / ha yr for experimental plots and for the 5 % was 17.38 odt / ha yr.
Context of energy crops analysed
The key issue to develop the renewable-based bioenergy is to produce bioenergy crop production with proper land management. (Mola-Yudego & González-Olabarria, 2010). About thirteen energy crops have used from the past decades in Sweden to fulfill their bioenergy demand. (Ostwald et al., 2013). Mainly short-rotation plants like whose have economic life span (20 to 30 years) and have short harvesting rotation (1 to 5 years) used for energy production (Christersson & Verma, 2006; Dickmann, 2006; McKay, 2011). For this purpose, salix genus especially the willow is more prevalent in the northern countries of EU. About
16,000 ha of arable land was cultivated by the willow which was about 0.5% of total arable land of Sweden (Mola-Yudego, 2010). But the land-use changes have an essential effect on the GHG balances and eutrophication (Börjesson & Tufvesson, 2011).
The utilization of biomass one of the most effective way of 12 principles for green chemistry. (Anastas & Eghbali, 2010). Which is responsible not only for saving the energy crisis in the future but also for mitigating global warming. Even replacing of biofuel reducing the nitrogen oxide emissions, that is compromising the air quality and improving the human health gradually. That had happened for excessive using of fossil fuels in developed countries. (Hoekman et al., 2018). Unfortunately, the world still fulfilling its 80% of energy demand by fossil fuels. Even that may increase by 50% in the next 20 years. (Ozturk et al., 2017). So bioenergy crop cultivation in a sustainable way is an important strategy to reduce the greenhouse gas emission in the environment. For the sustainable bioenergy crop cultivation, land management is a critical issue in the world. But Sweden is very successful in this sector because without doing any harmful effect on the environment they are improving their biomass production gradually from the last few decades. Which was in very noticeable amount. (European Union, 2009). Though some analysis has shown some contradictory analysis in these purposes (Kendall & Chang, 2009; Kim & Dale, 2009). However, for the bioenergy crop cultivation in arable land has some different explanations rather than biomass production from forest products or residues. It depends on the local conditions, different design of production system, different calculation method, or system boundaries. Also, other critical factors are connected, for example, types of lands, types of crops, the efficiency of nitrogen fertilization or other fertilizers, and the utilization rate of byproducts (Börjesson, 2009). Proper land use management for the energy crop cultivation may contribute for the environment by reducing greenhouse gas emissions, protect from the soil erosion and nutrient leaching, carbon balances in the soil, by treatment of wastewater that helps to reduce the effect of the heavy metals in soil and environment, protect biodiversity and so on (Börjesson, 1999).
Expansion of bioenergy crop cultivation in the arable land also has some effect on the socio- economic condition of Sweden. It is a very strong societal and political pull because it's connected with severely with the economy and environmental condition. It is a transitive way to change the world energy demand on fossil fuels. Many countries are trying to be self- dependent for their energy consumption rather than to export fossil fuels from the other country.
(Johnson et al., 2012). Sweden produces liquid biofuels mostly from the farmland by the cultivation of energy crops (Energimyndighet, 2012). Land-use change for the bioenergy crop
production may introduce the competition with the demand for food, feed and fibers, creates the new employment opportunity, increases the standard of living and also change the landscape and visibility of the countryside (Haughton et al., 2009).
The results focus on the salix, poplar, h. aspen and reed canary grass. The estimation of bioenergy fast-growing crop cultivation has increased suddenly after the 1990s oil crisis and environmental consciousness. Even in 1990, the estimation for the bioenergy crop cultivation was 2000 ha, but in 1992 it increased 5000 ha. The amount of estimation was highest at about 13,000 ha in 2002 (figure 1).
3.2. Review of environmental effects
Cultivation of bioenergy crops in arable land has flourished from the recent few decades because of the worldwide energy crisis and focusing on the sustainable energy sources with less environmental effects. But we should recognize that what kind of impact have on the environment and socio-economy because of the massive expansion of bioenergy crop cultivation in Sweden.
Energy is an essential criterion for development in any place in the world. If we compare with any fossil fuels, using bioenergy is most advantageous. The most benefit is to use biomass is the renewability of it. But due to its renewable characteristics, it has some severe environmental alteration process that may turn or change the environmental phenomenon. For this reason, it is completely interconnected with air, water, soil, and biodiversity in different ways. (Wu et al., 2018).
After 1970, the world's agricultural production has increased twice than before because of the sudden population growth and for the related requirements or food security. Also, for the worldwide fuel crisis, some country has started to cultivate the bioenergy crops in their fallen arable land. For this reason, about a quarter of the greenhouse gas has emitted from crop cultivation in 2010. (Bennetzen et al., 2016). From the previous discussion, we know that Sweden is the highest country using biomass energy crop cultivation in the world. In the world level, agriculture is contributing about 14% of anthropogenic greenhouse gas emissions, while 17% is happening for the changing of land use patterns. (Palut, 2007). So, finding out the greenhouse gas emissions for the bioenergy crop cultivation in arable land is an important issue.
Because of bioenergy crop cultivation in arable lands, the greenhouse gas emissions may reduce by three ways like a) reinstallation of carbon in mineral soils, b) less emission of carbon di oxide from the organic soils due to less ploughing of land, and c) less emission of nitrous oxide from the land due to less utilization of nitrogen or other fertilizers. (Börjesson, 1999).
Effects on Soil
The cultivation of bioenergy crops in arable land has many ethical impacts on the soil when if compare with the traditional agricultural crop cultivation. It saves the loss of soil humus and increased soil fertility. On the other hand, due to conventional agriculture crop cultivation, farmers need to do more intensive soil tillage, which is responsible for reducing soil fertility and loss of humus. (Bouwman, 1990). During the last 25 years of energy crop cultivation in Sweden, the humus level has increased on the topsoil about 1 percent. Increasing humus level means increasing fertility in the soils and the result of this is increasing the overall crop cultivation rate during the following years. The study has shown the harvesting of food crops has increased by at least 5%. (Gustafsson, 1987).). Whereas, physical and chemical properties were improved due to the high contents of humus level. (Andersson, 1990). Theoretically, about 47% of Swedish arable land has developed the humus level in mineral soils. The amount of collection for annual crops would be twice if the places were cultivated by the perennial energy crops (for example the Salix) previously for 25 years. But the amount may reduce according to the time and next criteria of cultivation. (Mattsson, 1996).
Also, after using the Salix plantations surrounding the food crop cultivation, wind erosion may reduce. Because of wind erosion plant blasting, roots uncovering, losing of organic matters and fine particles, seeds exploitation, and reducing soil fertility may happen. (Mattsson et al., 1996).
Some results from the previous study have shown that, if any area of annual cultivated crops surrounded by the perennial energy crops (for example the Salix), the wind erosion may reduce several times, and total production also be increased for this reason. (Jonsson, 1994).
To protect from the water erosion of soil, perennial energy crops (for example the Salix) have also good contribution. It may reduce the rill erosion especially from the clay and silty fields in hilly areas. But the water erosion may happen for low soil cover and extreme run-off in Salix plantations also. In Sweden, about 20% of arable land is exposed to rill erosion. If 5% of rill erosion happens about 500 kg/ha/year may loose from the topsoil. (Alstrom, 1991). So to save soil from water erosion, perennial energy crops (for example the Salix) cultivation to the surrounded area is an important way.
Carbon in mineral soils
For the reinstallation of carbon in land, it needs much amount of organic matter should be added, and less amount should be eroded at the same time from the soil. It happens when traditional food crops replace perennial energy crops because the rate of tillage would reduce.
Also, for the bioenergy crops, the input amount of organic matter remains high for the litter and roots. About 4.5-10-ton dry matter/ha/year may recirculate in established salix cultivation where nearly two-thirds have come from litter and one third by roots. (Sjödahl et al., 1994).
After harvesting the crops from the arable land, the abandoned materials of energy crops contain 60% of carbon also decomposed by the soil. (Reicosky et al., 1995). That affects the high enrichment of carbon in the topsoil. For example, several cultivations of salix in the same arable land within a few years increases the carbon content in the upper soil. Though the total carbon content remains unchanged, it may change after a long period. (Reicosky et al., 1995;
Makeschin, 1994). Even the cultivation of ley grass in arable land increases 30-40 tonne C per ha. Food crops need more than 30 years to get the same amount of carbon in topsoil. (Thyselius et al., 1992).
Soils have a close connection with other parts of the environment, like air and water. When soils also absorb three major greenhouse gases in its like Carbon dioxide (CO2), Methane (CH4) and Nitrous oxide (NO2). Even the vegetation of soil absorbs carbon and nitrogen through photosynthesis and nutrient up taking respectively. But after comparing with the size of traditional food crops, energy crops may absorb more carbon and nitrogen in their body.
Because if the stock of carbon and nitrogen be more inland than it is more favorable for the environment. (Höglund et al., 2013).
For the perennial crop, soils not cultivated regularly so the release of carbon not happened generally and the penetration of carbon increases through the roots. But for traditional annual crops, the possibility of carbon input is in little amount, and the carbon release is common.
Organic soil may grow 0.1 to 1 ton per hectare in the topsoil (30 cm of the above part of the soil) for the cultivation of perennial grasses. (Hillier et al., 2009). High rates of carbon accumulated in Nothern Sweden for the cultivation of reed canary grasses within the first three years. About 3 to 3.4 tons of carbon accumulated in the top 20 cm of soil per hectare. This amount is about seven times higher than the traditional agricultural food crops. (Xiong &
Kätterer, 2010).
Soil carbon sequestration had increased in Sweden for the cultivation of poplar and willow.
After calculating the 20- and 22-years harvesting cycle of willow and poplar based on the leaf litter observation and decay modeling, 2.81 and 3.51 tonnes of carbon per hectares produced for willow and poplar litter (leaf + fine roots litter) respectively. (Rytter, 2001; Rytter, 2012).
On the other side, the soil carbon accumulation is about 0.41 tons and 0.52 tons per hectares for willow and poplar, respectively. (Berg & Ekbohm, 1991).
The primary source of nitrous oxide (N2O) emissions for greenhouse gas is the agricultural sector. Even nitrous oxide emission is more harmful than carbon dioxide emissions. Because 1 kg of nitrous oxide (N2O) has 100 years of climatic impact, but to get the same kind of effects in the environment, we need about 300 kg of carbon dioxide (CO2). Sweden releases about 70% of nitrous oxide (N2O) from the agricultural sectors. (Kasimir, 2009). Though nitrous oxide (N2O) is more effective than carbon dioxide (CO2) but the source of nitrous oxide (N2O) emissions are not so much frequent like the carbon dioxide (CO2). It is mainly happened for the excessive use of nitrogen fertilizers in the agricultural fields when the utilization of nitrogen fertilizer for the forest growth and bioenergy crops are not so common (Nordin et al., 2008).
For example, in Northeastern Germany, emissions of nitrous oxide were half from salix and poplar comparison with annual crops (Hellebrand et al., 2010).
Carbon emmissions
Vegetation on the arable lands accumulate a huge amount of carbon, nitrogen and other minerals in different quantity. For this reason, the soil surface acts as a significant carbon and nitrogen reservoir, but due to the cultivation of crops, it becomes light and releases many organic matters and minerals. Among them, carbon dioxide (CO2), methane (CH4) and nitrogen oxide (N2O) are more critical because of quantity and impacts on the environment.
(Höglund et al., 2013).So, changing of land use pattern has a significant contribution to the emission of carbon. It's entirely depended on the soil and vegetation types. In this perspective, the accumulation of carbon rate is higher for traditional agricultural crops than the perennial energy crops because of frequent soil tillage. The rate is 2-3 cm per year for the carrots and potatoes. For the permanent pasture, the rate is 0.5 cm per year, in the same way, 1-2 cm for grain and 1 cm for ley. (Berglund, 1989). In the same way, perennial grass cultivation in arable land may increase the organic carbon at about 0.1-1 tons per hectare per year. High accumulation rates also happened for reed canary grass in three different growing stages. In the
upper 20 cm, the rate was 3-3.4 tonnes per hectare. In the second and third generations, the rate was more than the first growing season, and it was two to seven times higher than any other agricultural food crops. (Xiong & Kätterer, 2010). The accumulation rate for willow and poplar is higher than the other. Willow increases about 2.81 tons of carbon per hectare per year during their 22 years harvesting life cycle. While poplar accumulates 3.51 tons in the whole 20 years life cycle. This calculation was for total litter (leaf + fine root litter) (Rytter, 2012).
According to this, it is possible to do an estimation that, bioenergy crop cultivation in arable land rather than the agricultural crop cultivation may reduce the carbon from 2 to 1 cm per year.
It means about 7 tons of carbon reduces per hectare per year when the total content and density of carbon in Swedish organic soils were 200 kg/m3. (Berglund, 1989).
Nitrogen emmissions
The emission of nitrogen mainly happens because of the extra use of nitrogen fertilizers, whereas the requirement of nitrogen fertilizers is shallow or ignore able for bioenergy crop cultivation. On average, about 50 kg of nitrogen needs in a hectare for energy crop cultivation.
Beside this, due to have an extensive root system and more longer growing season, nitrogen loses from the topsoil of arable lands is negligible for the bioenergy crop. Another reason might be the low availability of nitrogen minerals in the topsoil of Sweden. (Börjesson, 1996). An estimation for the bioenergy crop cultivation may reduce the N2O emission at about 0.3 kg per hectare per year had established by the Bouwman and National Swedish Environmental Protection Board. (Bouwman 1990; National Swedish Environmental Protection Board, 1990).
Also from Ahlgren, the N2O emission rate is like, for ley grass 0.5, willow 2.1, ley crops 2.5, sugar beet 3.0, rapeseed 3.1, wheat 3.6, maize 3.7. All amounts are in kg per ha per year according to IPCC rate of 2006. (Ahlgren et al., 2010). So it means that, energy crops release less nitrogen than the agricultural food crops.
Wastewater Treatment
The wastewater treatment output depends on the nutrient contents of the water and the nutrient demand for energy crops — most of the cases the wastewater used as the supplement of fertilizers. Because the wastewater contains many organic and inorganic materials, those are important for bioenergy crop growth. (Perttu et al., 1994). After using the wastewater irrigation, the production of bioenergy crops may increase more than 2-3 times, compared without using the fertilizers. (Nielsen, 1994). Some studies have shown that, if the Nitrogen and Phosphorus
contain are 500-1000 mm/ha/yr, then about 75-95% of the elements are possible to remove by the cultivation of energy crops from arable lands. Even if the amounts are high like 2000-5000 mm/ha/yr, then still, it is possible to decrease 10-55%, according to the soil contents and vegetation types. (Perttu et al., 1994). During the summertime, the amount of Nitrogen contents in wastewater remains high because the utility rate of nitrogen per person in the municipality remains high. On average, the percentage of nitrogen utility is about 4kg/person/year. (National Swedish Environmental Protection Board, 1993). For 600 mm/ha/year of nitrogen in wastewater, mainly carrying 125 kg Nitrogen in solid condition. But this amount has not only long-term effects on the environment. (Perttu et al., 1994). Though, in some cases, Sweden uses some pretreatment to reduce the high nitrogen contents by cultivating other vegetation.
(Rosenqvist et al., 1997). It is possible to treat about 70% of the municipal waste of Sweden by bioenergy crops. Then it needs about 100,000 ha of arable land, which is equivalent to 3.6% of total arable land. (Statistics Sweden, 1996). Some energy crops have a high evapotranspiration rate than other traditional agricultural food, like salix and reed canary grasses. This kind of plant reduces the nutrient leaching to soil and groundwater levels. When leaching is the most significant effect for the wastewater about every 3-hectare size of energy crop cultivation can reduce 150g N per liter leaching from the topsoil. (Perttu & Aronsson, 2013).
So, if the wastewater used for bioenergy crop production, it saves water from some severe pollution of water. It also protects from excessive nutrient leaching to soils and underground water. But there has some little risk for discharging heavy metals from wastewater. Because the amount of released heavy metals from the municipality on the environment may become ignorable because of the low quantity, even the high concentration of heavy metals problem could be solved after the frequent cultivation of bioenergy crops in a specific area.
Effects on Biodiversity
Biodiversity is an important indicator to realize environmental stability because it indicates food production and about all kind of ecosystem services. (Qin et al., 2018). Initial land use condition, landscape configuration, and the types of bioenergy crops production profoundly affect biodiversity. Due to direct land-use changes and changes in the production system, biological abundance may affect seriously. This land-use conversion changes the plant kinds and locations that affect depended on biodiversity. If the direct replacement happens for changing the grassland to bioenergy crops that may help to increase the productivity of ecosystem functions. (Correa et al., 2017). Besides, many studies have shown that Miscanthus has a less negative impact on biodiversity comparison with traditional annual crops. Because
perennial crops give more stable habitation for the wildlife. (Rowe et al., 2009; Werling et al., 2014). In addition, energy crops cultivation in the grassland or abandoned land may change the landscape design. If better management may practice in the land that could reduce the risk of biodiversity loss. (Manning et al., 2015).
From the biodiversity perspective, bioenergy crops cultivation has a significant impact on arable land also. At first, it directly affects the soil organisms like on different bacteria and fungus, various decomposers, earthworms, carbides, woodlice, and harvestman. Also, the vegetation of bioenergy crops acts as the primary food source for the different types of primary consumers like rabbits, moose, and even for some insects in the surrounding food webs.
(Makeschin, 1994).
Bioenergy crops on the arable land act as a suitable and safest habitat for any small and micro- organisms. Because of the bioenergy crops cultivation, the farmers need a minimal amount of chemical pesticides (0.2 kg/ha) rather than other traditional agricultural food. For traditional agriculture crops production, the farmer needs to use about 1 kg chemical pesticides in a hectare. (Börjesson, 1996).
Some study has shown that, after the cultivation of salix crops, the production of pollinating insects like bees have increased. That has a positive effect on the production of other plants.
(Björklund et al., 1999). It has estimated that about twelve salix plants may help to an occurrence at least 125 species of vascular plants. (Gustafsson, 1987).
On the other hand, for the transition of wildlife, the short-rotation forest act as a heaven. Only in the summertime, about 25 species of birds make a habitat in the short rotation forest. It happens because of the maximum source of food from insects in the bioenergy cultivation.
Also, about seven species of wild animals have come to take their maximum meal. (Sage &
Robertson, 1994; Paine et al., 1996).
Though, massive cultivation of bioenergy crops has some adverse impact on the environment, it may increase the growth of different pests like fungus, insects, and herbivores. Those pests may spread to the other vegetation and may hamper the ecosystems (Christerssonet al., 1992).
Another big problem with the massive cultivation of bioenergy crops is genetic contamination.
If the bioenergy crops are cultivated on big arable land for an extended period, it may contaminate the genetic species diversity. (Official Report of the Swedish Government, 1992).
4. Conclusions
The bioenergy crop production in Sweden in arable lands is increasing gradually. At now, about 13 kinds of energy crops are producing but previously it was only a few. In 1985, the total cultivated land for energy crops was less than 1000 ha for willow cultivation. But later in 2007 to 2012, only hybrid aspen was cultivated in 500 ha to 980 ha respectively. In the same way, 14000 ha arable land was cultivated in 2004. For reed canary grass, at 2000 it was 100 ha but in 2015 the amount has risen about 800 ha. So we can say that Sweden is increasing more arable land for bioenergy crop cultivation. Not only for economic purposes bioenergy crop cultivation also has some environmental benefits.
The study also has shown how bioenergy crops are contributing to develop the environment. It has all kinds of benefits on the environment for example on air, water, soil, and biodiversity.
During the last 25 years due to bioenergy crop cultivation in arable land, the humus level has increased more than 1 percent. And because of this, total crop production has risen 5%. Now 47% of Swedish arable land has developed the humus level. The carbon accumulation for energy crop cultivation was 0.1-1 tons per hectare per year. And nitrogen emission reduces 0.3 kg per hectare per year, so it has a good impact on air also. By absorbing different heavy metals and a high amount of Nitrogen and Phosphorus from wastewater, bioenergy crops also increasing the quality of water.
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