Using marginal and non-marginal soil for biofuel production

From an agricultural point of view, the soil is thin upper mantle of rocks in which plant roots penetrate and where this take water from, as well as other substances necessary for its existence, being it main components inorganic compound, soluble nutrients, organic matter, water and gases (^{Crespo, 2004}). The ground provides nutrients to the vegetation, necessary for its operation (^{De las Salas, 1987}) hence the importance of this component as if there exist an imbalance in its temperature and composition, will affect food production. Soil classification (Table 1) is founded on erosion, but is useful to draw a distinction between non-marginal soils (suitable for agriculture) and marginal (not suitable for agriculture). In addition that erosion is a major soil degradation processes ^{De las Salas, 1987}; ^{Gandía y Meliá, 1991}). The term marginal land is used to refer to abandoned spaces as consequence of their low productive value; that is, are those soils (as synonymous of agricultural land) located in areas with low and unpredictable rainfall, and where temperature and relief conditions (land) restricts natural productivity and the establishment of agricultural systems (classes V to VIII) (^{Gandía and Meliá, 1991}). Non marginal soils shall be understood as those considered in classes I, II, III and IV (^{Gandía and Meliá, 1991}).

Table 1 Soil classification by type of erosion. 

Fuente: ^{De las Salas (1987)}. El suelo como componente del medio. Relación suelo-clima-vegetación.

Nowadays, the issue of biofuels has taken relevance for environmental reasons (lower CO₂ emissions to the environment) and economic (increase in energy demand worldwide) and productive as the decline of traditional fossil fuels and instability and volatility in their price (oil and coal) (^{SAGARPA, 2006}); so it has generated an increase in demand for agricultural products for energy production (^{IICA, 2007}). For example, sources for energy production in 1980 were oil (43%), coal (25%), gas (17%) and biomass (10.5%) which covered 95% of human consumption; for 2004 the same sources contributed 91% and by 2030 will cover 89% of world consumption (^{López, 2007}). Oil reached record prices both upward to over 100 USD per barrel and downwards to less than 43 USD per barrel in 2014 (^{Fernández, 2008}).

Biofuels are liquid fuels produced from agricultural crops that are obtained by the industrialization of products, such as ethanol from corn, wheat or sugar beet and biodiesel from oil seeds (^{Seoánez, 2002}; ^{Demibars, 2008}). Biofuels are obtained by the industrialization of traditional and non-traditional agricultural products such as safflower (^{SAGARPA, 2006}); sugar cane, cereals and beets are used to produce bio-ethanol as a gasoline substitute while vegetable oils are used for biodisel production (^{IICA, 2007}), but the production of biofuels has been based mainly on corn and sugar cane crops for two reasons: 1). These crops have the highest crop yields for ethanol production (^{Cunningahm, 2007}); and 2) 90% of the total production of biofuels are destined for ethanol (^{IICA, 2007}). So biofuels production, mainly ethanol has generated interest in developed countries with the aim of creating an energy source that is used mainly in transport, allowing them to reduce their dependence on foreign oil (^{Cunningahm, 2007}).

Advantages of using non marginal soils for the production of biofuels

Currently, oil shortages and high prices of it affect global economy ^{IICA, 2007}; ^{Alessandro, 2006}), so there is a need to find alternative energy sources to oil and renewable. Biofuels, mainly corn and sugarcane are produced in nonmarginal soils.

There are international protocols like Kyoto, which set the reduction of greenhouse gas emissions; and it is through the use of biofuels as it is intended to achieve this reduction to reduce global warming.

The change in energy sources and the reconversion of agriculture to the production of biofuels will enable Latin American countries to export higher production to industrialized countries. ^{Bravo (2001)} according to statistics from the European Commission, says that Europe will become the largest importer of agricultural products for both consumption and production of biofuels and Latin America will be their main supplier; since European Union imports 75% of vegetable protein only to feed livestock (^{Alessandro, 2006}; ^{Bravo, 2001}).

US, Mexico’s main trading partner imports 61% of crude oil that consumes, so it has sought to reduce its dependence on foreign oil through the production of biofuel (bioethanol) made of corn (^{Pimentel, 2003}); it is the leading producer of grain worldwide (^{SAGARPA, 2008}).

Greater economic dynamism in countries with emerging economies, which represents a business opportunity for Latin America and mainly for Mexico. ^{Walter (2005)} mentions that for Latin America have been generated large megaprojects for biofuels production or to find sustainability in the production of monocultures from corn and sugar cane for biofuels production.

Disadvantages of using non marginal soils for biofuel production

Increased food shortages; in industrialized countries, have begun to replace the use of oil for biofuels which has generated a reconversion of agriculture (mainly bioethanol) (^{Soonet, 2007}).

Economic and political pressure from economic powers on countries with emerging economies, for the supply of raw materials for both biofuel production to consumption; which would lead to food shortages in developing countries. In this regard ^{Soonet (2007)} mentions that industrialized countries have begun to replace oil production for biofuels either in their farming systems or by importing raw materials from emerging economies.

The use of non-marginal soils intended for food production will be shifted to biofuels production. For example, South Dakota, Minnesota and Iowa, main corn producers in the US, spend 50% of their production to biofuels production; generating a deficit in corn supply for human consumption and livestock. Another example is in the European Union (EU); who agreed that by 2020 all fuels (used in transport) should have 10% of biofuel source, so it will have to allocate 72% of agricultural land to energy production (^{Bravo, 2001}).

Emerging economies do not count with enough production volume to allocate it for human and animal consumption and allowing them at the same time biofuels production or export it. According to the Ministry of Agriculture, Livestock, Fisheries and Food, ^{SAGARPA (2008)} in 2007, of the total maize availability (production and imports) that Mexico had, 56% was used for human consumption, 27% for livestock, 11.5% for industry, and 5.3% for other uses.

The establishment of monocultures such as corn and sugarcane, both for human consumption and for biofuels production will increase the number of pests and diseases by lack of crop rotation (^{Pimentel, 2003}).

Pros of using marginal soil for biofuel production

The use of areas not currently used for agricultural production. So it could be occupied soils classified as IV, V, VI, VII and VII as long as it develops technology (varieties and equipment) for such purpose (^{De las Salas, 1987}).

Crop production for bioenergetics purposes on marginal soils is feasible, and do not compete with production intended for human consumption in terms of soil, water availability and other resources needed for production (^{Bravo, 2001}).

Incorporating commercial production to producers, whose products are intended for home consumption, would generate greater economic benefits for them.

Use of non-traditional products (such as beets), that enables biofuels production; so that the production of traditional crops is destined for human consumption and livestock and cultivation of nontraditional for biofuels production; thus, food deficit problems would be avoided; this under the premise that the agronomic characteristics of nontraditional crops are appropriate for their establishment, development and production on marginal soils.

Cons of using marginal soils for biofuel production

Both maize and sugarcane require specific ecological conditions for its development and operation to enable an adequate production for the generation of biofuels; but most marginal soils lack these conditions. So climate-plant-soil relationship should be considered as an integrated system. In the specific case of sugar cane, ^{Jiménez et al. (2004)} states that inappropriate soil characteristics creates restrictions on crop development and function.

According to soil classification presented, corn and sugar cane crops as the main crops used for biofuels production cannot be established on marginal soils (classes IV, V, VI, VII and VIII).

Furthermore, according to the points made by ^{Cunningahm (2007)}, corn and sugar cane present the highest crop yields for ethanol production; but by not having the right ecological conditions, the yields will be lower than expected or even null. Aspect related to the definition of "marginal lands" (abandoned spaces due to their low productive value).

^{Bravo (2001)} mentions that the incorporation of marginal lands for biofuel production is not a solution that allows everyone involved to obtain benefits; since, in most cases, marginal soils are in hand of indigenous or producers that allocate them for self-consumption production, and the attempt to remove them from this type of production to incorporate them into agriculture for biofuels production can generate disturbances in land owners.

Moreover, in most cases it will require appropriate technological packages to enable crop establishment, development and production (traditional or non-traditional) for biofuels production in order for yields obtained are sufficient to meet the demand of materials for the biofuels production.

Produce food or biofuels?

Population growth, climate change in the production cycles and the instability in them due to the effects of climate change such as atypical droughts and floods and the search of alternative energy sources based on agricultural crops have generated a global crisis with local repercussions, due to globalization, for food availabilit both human and animal consumption that has generated a rise in prices (^{FAO, 2007}). It is estimated that the population will grow to 9 billion stabilizing in 2040-2050; enough food to meet the nutritional requirements during the first half of the century will be approximately equal to the total amount of food produced throughout the history of mankind (^{Capper et al., 2008}); these factors together have generated a global crisis in food availability, causing an increase in food prices like sorghum and corn (^{Soonet, 2007}; ^{FAO, 2007}).

For its part, the World Bank (WB) estimates that grain prices will continue to rise steadily until 2015 therefore it recommends to the countries to redefine its agricultural policy in order to ensure the supply of grains. For example, the international price of corn in 2006 was 87.66 USD t^-1 for January 2008, the price per ton in the international market reached 194.32 USD t^-1 having an increase of 121.7%; meanwhile in sorghum, for the same period had an increase of 83% (from 94.2 to 172.8 USD t^-1) (^{Fernández, 2008}); The WB, from that five years, estimated the increase in grain prices steadily until 2015.

Added to this, if for the past five years, US the main producer and exporter of corn expected to allocate 30% of their harvest (over 12% of world production of corn) for biofuels production (ethanol) (^{Cunningahm, 2007}; ^{García, 2008}). By 2050 the supply of biofuels will require 385 million hectares being established the production areas in developing countries (^{Demibars, 2008}; ^{Walter, 2005}). In the case of Mexico, in 2009 was approved the Law for the Promotion and Development of Bioenergy (LPDB), which stipulates that only corn surplus production will be allocated for biofuels production; however, the country is not self-sufficient in this area; in the short term for biofuels production (ethanol) it would have to spend 700 thousand hectares and in 20 years one million 700 thousand, time in which will increase the expenses on corn and sugar cane imports ^{García (2008)}.