ON SUGARCANE AND SOIL EROSION IN BRAZIL

Relevant links:

http://www.evworld.com/view.cfm?section=article&storyid=1107

http://www.solovivo.com/

Depending on how a soil is managed along the successive culture cycles, it may degrade severely, losing progressively its capacity to hold water, air and LIFE. Consequent destruction of its aggregates results in compaction and/or erosion.

Sugar cane and soil erosion

Milton Maciel

Depending on how a soil is managed along the successive culture cycles, it may degrade severely, losing progressively its capacity to hold water, air and LIFE. Consequent destruction of its aggregates results in compaction and/or erosion.

If this happens in the sugar cane industry, all depends on how cane is cultivated and how its processing residues are returned to the culture land. For best results, it is mandatory that cane isn't burned for making harvest easier. At the origin of all is the large biomass that not-burnt cane leaves on field.

Stalks, taken to the mill, are just a part of what the cane plant produces yearly. A large mass of tops, green leaves and dry leaves (trash) remain over the soil after the cane is harvested. This may exceed 15 tons/year as organic DRY matter. Aerobic digestion takes a part of that to the air as carbon dioxide and water vapor. And the remaining material results incorporated slowly to topsoil, contributing with crude organic matter, then humic and fulvic acids as it is turned into humus and then mineral nutrients as it finally mineralizes. During the process, that layer serves also the functions of protecting soil against heavy rains and winds and making emergence of weeds much more difficult.

In round numbers, each plot of integral harvested sugar cane results in

15% sugar

15% bagasse (dry matter)

15% trash (dry matter)

Trash is the combined result of dry leaves, green leaves and tops, all left over the harvested plot or burned, meanwhile the stalks are taken to the mill.

To burn or not to burn?

This mixed residue is burned in order to make manual harvest easier, safer and more yielding. The combustion of trash has a tragic record for soil fertility and is a clear squandering of a very rich source of organic matter and nutrients for this soil. Most minerals remain at place as ashes, but nitrogen and sulfur are lost to the air, contributing to pollution, as their oxides are harmful to environment and human health. Of course, burning cane is also a process of liberating CO₂ to atmosphere, contributing to global warming, instead of making a considerable part of this Carbon available to soil life and fertility. As sugar cane burning fumes have very harmful effects on the health of people in the cities near by, pose dangers to aerial navigation, and is also harmful to the manual harvest workers themselves, it is to be phased, by force of law, until the year 2018.

But we have to consider not only the loss of matter (sulfur, nitrogen, carbon), but also the absurd loss of ENERGY that goes with the hot gases of trash combustion in the fields. Some studies point to the possible use of trash as a source of energy in the factory, for feeding its boilers, replacing a large part of bagasse. This surplus bagasse could then be employed to produce more ethanol (since cellulosic ethanol process may become economically feasible) or other byproducts. For the moment the main obstacle is HOW to harvest and transport this trash to the mill.

Organic sugar and ethanol mills say that they would never prefer not to take trash to the factory, as they use the whole mass of trash to protect soil, combat weeds and, more important, to recycle nutrients. They affirm that this is one of the principal reasons why their stalks yield is so much larger than that of conventional farms (plus 30%) and why the useful life of the cane plantation is also much larger (plus 50%, average).

Anyway, both in organic or conventional sugar cane farming, mechanical harvest is the best way to avoid burning and of preserving the best soil protective and nutritive qualities of trash.

When managed so, especially under organic cultivation, sugar cane can contribute to a regenerative effect on soil fertility. To explain this may be somewhat long and somewhat technical, but is extremely simple. I’ll start considering the most severe depletion that cultures cause in topsoils, EROSION. The nutrients issue may come in a following post, if you wish.

TYPICAL EROSION RATES FOR SUGAR CANE AND OTHER CROPS IN BRAZIL

Let’s consider first the worst case design, when sugar cane is produced by conventional chemical agriculture and is submitted to the use of fire at the moment of harvest. Typical measured erosion is 12 ton/hectare of top soil/year (#1). When cane is not burned and the remaining shopped pieces of tops, green and dry leaves are left standing over ground, erosion rate is 5.7 ton/ha/year (#2). This is the typical result of harvesting green crude cane with a combo mechanical harvester.

The first number seems to be high; but as we compare it with erosion rates for other cultures, we find, under the same conventional agriculture methodology, in Brazil:

CROP…………………EROSION rate (in ton/ha/yr)
Castor oil beans..…………..40
Beans………………………..38
Cotton…………………….....25
Soybeans..………………….20
Sugar cane (#1)…………….12 (burnt before harvest)
Sugar cane (#2)……………...6 (biomass of chopped tops, green and dry leaves left over ground)

Sugar cane (#2.0), ………….0 (organic: actually there is a net gain of material in topsoil)

[For all crops, for sake of comparison, we consider a standard soil slope of 10%, limiting value for mechanical harvest of sugar cane].

Now let’s first understand the architecture of the sugar cane plant. STALK is the part of sugar cane plant that is taken to factory, in order to be pressed in the mill for extracting the sugary juice. The other parts of the plant stay on the culture plot.

As I can’t use a picture here, please just imagine (or make a simple draw yourself) you have a 3 meters (~10 feet) high plant. For making things easy to understand, suppose you cut this plant at a height of 2 meters and also cut it close to the ground. This piece is the STALK. The remaining upper part is the TOP. Top’s juice doesn’t have enough sugar and has undesirable components in it; that’s why it is uninteresting to the mill. Attached to stalks and tops there is a lot of leaves. Most of the stalks leaves are old and die as the plant grows. These are DRY leaves; a great part of these leaves fall spontaneously (deciduous leaves) and cover the ground with a protective layer. There are also many newer leaves, alive and making photosynthesis, attached to stalks and tops. These are the GREEN leaves.
When cane is burned, fire propagates very easily because of the great mass of those dry leaves over the soil and dry leaves still attached to stalks. Then green leaves are dehydrated and burn too. Part of the tops still remains and all stalks resist the high temperature, because of its high (70) % moisture content. Under such conditions, a large part of biomass is lost, but most mineral nutrients remain in the resulting ashes, made available to the new cycle of growing through water of rains – except for nitrogen and sulfur, that are lost to the air as oxides, in fumes.

The only partial protection that this culture land receives is that proportioned by fallen dry leaves during the second half of culture cycle of one year. During the first months after harvest, when plants are growing again, leaves are new and of low height. With a standard distance of 1.4 meters (~5 feet) between rows, soil is bare, with limited protection from the trash that remains over soil, after burning and after cut tops are left on ground. Soon after harvest, starts the rain season and, under severe tropical rains, most of the erosion occurs. Under these circumstances, weeds thrive and cultivation is required, mechanical or chemical (herbicides). More erosion! Then, along the rain season, as the plants grow and grow, emitting ten or more stalks per plant and a lush of new leaves, they eventually get to cover the whole area, leaving conditions for weeds development and for erosion very unfavorable.

You must consider that I’m not mentioning anything about organic cultivation until this moment. So, the better score for conventional sugar cane (#1), when compared to other crops, is to be credited only to the sugar plant itself - its architecture, its cycle, its characteristic of semi-perennial culture, its deciduous (=falling) dry leaves, its very high photosynthetic conversion, its very high biomass production. As I always say, this plant is a kind of miracle of Mother Nature. You could never compare this plant culture with a culture of corn, aimed to the same objective of producing ethanol.

Now, before I can proceed and talk about organic cane’s soil regenerative possibilities, I would like to put those numbers on erosion under a frame of reference, so you can evaluate what they mean. When I say that a soybeans’ plot shows a typical erosion rate of 20 tons/ha per year, you have to consider that:

1 hectare = 10 000 square meters

Then suppose you cut a slice of that whole hectare, with a 20 cm depth. Your volume would be

10 000 m2 x 0.2 m = 2000 m3

This two thousand cubic meters is the volume of this 20 cm slice. It is the typical volume of this area TOPSOIL (Horizon A). Now let’s see what would be the weight of this topsoil layer, in tons:

Well, now we have to remember that the average DRY density of soil is somewhere between 1.52 grams/cubic centimeter for pure sand and 0.9 for a forest topsoil (it’s so light that it would float on water, if we could seal it against leakage).

Let’s say we have a SILT LOAM, whose dry (or bulk) density is 1.28 g/cm3. Evidently, the corresponding REAL soil would be lighter, because it would have to include a water and an air phase too. But let’s only consider that dry density:

We have 2 000 m3 of topsoil, with a dry density of 1.28 g/cm3

As 1g/cm3 = 1 000 000 grams / m3 = 1 ton/m3, we may now calculate:

2000 m3 x 1.28 ton/m3 = 2 560 ton/hectare is the weight of our silt loam topsoil

Then consider erosion rates. Divide them by 2 560 tons/ha and multiply by 100:

Beans……………..…..38 ton/ha/yr………..1.48% per year
Soybeans………….….20 ton/ha/yr………..0.78%
Sugar cane (#1)……...12 ton ha/yr………..0.46%
Sugar cane (#2)……….6 ton/ha/yr………...0.23%
12 tons is the weight of a slice of topsoil that is:

2 560 tons - 20 cm
12 tons - x cm Then x = 0,1 cm DEEP = 1 MILLIMETER

A ONE INCH (2.5 cm) layer of one hectare of this silt loam would weight:
20 cm – 2 560 tons
2.5 cm – x tons where x = 320 tons

Then, 320 / 2560 x 100 = a 12.5% yearly erosion would be needed, to loose one inch of this silt loam topsoil.
Of course no good professional farmer would loose such a foolish amount of soil in one year.

In short, these are the reasons why sugar cane is so much more efficient, at the culture field, than any other plant used for producing ethanol, including its marvelous low rate of soil erosion and high yield of both biomass of cellulosic material and sugar.

Follow what's happening in the Brazilian ethanol market on Ethablog, the only blog in English dedicated to Brazilian ethanol.

BRAZILIAN ETHANOL AS A BACKSTOP ALTERNATIVE TO OIL

My comments on the piece below:

The following paragraphs are a small part of a brilliant article by economist David Cohen, and were taken from “The Oil Drum”, a site that discusses Peak Oil and its consequences.

Mr. Cohen notes that biofuels are one of the only alternatives to gasoline derived from light, sweet crude. The only other remotely-viable options are heavy oil shales and tar sands, both of which are big polluters and very costly to process.

To Mr. Cohen acknowledges that there is, indeed, a substantial difference between ethanol made from corn and ethanol made from sugarcane. He believes that “the current enthusiasm for ethanol from a corn feedstock (as opposed to Brazil's use of sugarcane) is a good case in point. The hyperbole (surrounding corn ethanol) leads to a false belief that the substitute under discussion is a perfect backstop for conventional oil.”

The section below comes at the end of a rather lengthy and informative article. I encourage you to read the rest by clicking here. H.O.

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The Tragic Consequences of the High Discounting of Oil Extraction

An economic theory of finite non-renewable resources refers to a perfect backstop. This is more widely known as a complete substitute for the resource under consideration, which is conventional oil in this case. If such backstop exists, then Hotelling theory predicts that the price should rise according to Figure 6, taken from Khanna.

Figure 6 – Impact of Backstop Resource. Pnr indicates the price of the non-renewable resource; Pb indicates the price of the backstop. Tnr indicates the depletion of the nonrenewable resource.

The fundamental insight is that the price rises and the remaining resource stock is all used up prior to the switch because the existence of a perfect substitute renders the resource worthless. In theory, when the price reaches the backstop price, all of the resource would have been consumed and substitution occurs. Therefore, the perception that perfect substitutes actually exist increases the extraction rate of the resource.

Do perfect substitutes for conventional oil exist? The answer is "No". There is no perfect backstop but there are a plethora of imperfect substitutes—that we might call wedges—that might replace some part of the role conventional oil plays. The very notion of a substitute for oil is fuzzy. Note that in the general case, almost any abundant source of hydrocarbons, regardless of considerations affecting their production, is perceived as a backstop for conventional oil. Here is a brief list of the main wedges.

1. Canadian tar (oil) sands
2. Orinoco heavy tar
3. Coal/Natural Gas/Biomass to liquids
4. Oil Shales
5. Electric transportation
6. Wind, Hydro, Solar and Nuclear to support #5

It is important to remember that when one hears hyperbole about any of these substitutes, it is not the case that any of these backstops is perfect because they don't scale or their net energy return is low (if not = 1) rendering them expensive —and in the worst case— uneconomic to produce. This is just a partial list. The current enthusiasm for ethanol from a corn feedstock (as opposed to Brazil's use of sugarcane) is a good case in point. The hyperbole leads to a false belief that the substitute under discussion is a perfect backstop for conventional oil. Kronenberg states that for both the resource owner O and the resouce consumer C, this can lead to what he calls strategic interactions that lead to serious market failures.

Strategic Interactions

Here is a description of the game that Kronenberg terms strategic interactions.

* The resource owner O knows the total stock of the resource. The resource consumer C does not.
* C has the option of developing a backstop technology at any time
* O can delay the development of the backstop by influencing C's decision by lying about the stock of remaining resources.

Here is the result as described by Kronenberg (page 25):

Thus, if there are information asymmetries between the owners and consumers of a resource, strategic interaction takes place, and credible announcements play a critical role. Specifically, resource owners will have an incentive to overestimate the resource stock, so as to delay the development of substitutes for the resource. To make this announcement credible, they have to follow an extraction path consistent with the overestimated resource stock, so extraction will be faster than socially optimal. Resource consumers will have an incentive to announce the development of a backstop technology, and resource owners will react to this threat by raising the extraction rate and lowering the resource price (if the demand curve is downward sloping). In both cases, resource extraction occurs faster than socially optimal.

This interaction may be viewed as a reason for the failure of the Hotelling model. In fact, the suspicious OPEC reserves increases that took place in the 1980's is cited as a possible example and Kronenberg notes that resource (both national and state-run) owners have clear incentives to systematically over-estimate their remaining reserves which, in turn, leads to serious market failures. In order to manage consumer perceptions, extraction must remain higher than is socially optimal for a finite non-renewable resource in all cases.

Follow what's happening in the Brazilian ethanol market on Ethablog, the only blog in English dedicated to Brazilian ethanol.

APPLES, ORANGES, SUGARCANE AND CORN

Milton Maciel speaks with the authority of a former government official who served as Secretary of Agriculture in Brazil’s northeastern state of Alagoas, one of Brazil’s main ethanol-producing regions.

ETHANOL, OIL AND EROEI

Milton Maciel

From Brazil

Relevant links:
http://www.solovivo.com/

http://www.evworld.com/view.cfm?section=article&storyid=1107

The standard method for evaluating net energy of an energy resource is the measure known as EROEI, meaning Energy Returned On Energy Invested. If this number is larger than one, then we a have an energy source. If EROEI is lesser than one, then we have an energy sink.

One of the most controversial issues now is the figure for EROEI for ethanol. As corn ethanol EROEI is so low (1.3 : 1), in USA, there is in this country a general trend to nail sugar cane ethanol in the same coffin. However, this is a problem specific with corn and its conventional agrochemical cultivation, less efficient than sugar cane cultivation under the ideal conditions it finds in Brazil tropical land, where it is grown rain fed, avoiding the use of expensive and water depleting irrigation.

Sugar cane ethanol EROEI, under correct technologies, is much higher than that for corn ethanol.

Its minimum figure of 8.3 : 1 (as of 2001) is now already outdated, even for conventional cane cultivation, in Brazil. Not only in cultivation technologies, but also in industrial distillation processes, further advancements were achieved. The new study we’re preparing for publication now shows considerable higher results for 2007 and an at least 20% increase in EROEI figures in the coming two years. This holds for conventional chemical sugar cane. When we apply figures to organic sugar cane, EROEI has a potential for further increasing, theoretical limit being as much as 50% higher.

With an average yield (5 years) of 85 tons/hectare of cane stalks in south/center region, for conventional chemical cultivation, and an average of 85 liters of ethanol produced from each ton of cane stalks, we have an average production of 7225 liters of ethanol per hectare. (1 hectare = 2.47 acres)

With an average (9 years, least case) of 109 tons/hectare of cane stalks in the same region (where 85% of all Brazil’s sugar cane is produced) for organic cultivation and the same industrial average of 85 liters of ethanol per ton of stalks, we have an average of 9265 liters of ethanol per hectare.

As a comparison, corn ethanol production, for an average high yield of 150 bushels/acre in corn grain, is 400 gallons/acre, the equivalent of 3750 liters/hectare.

Why is sugar cane so more efficient?

First is the reality that sugar cane is just a rude perennial grass that is farmed as a semi-perennial culture, while corn is an annual culture, one that must be sown every year, with the corresponding expenses in seeds, energy, fertilizers and soil movement, plus a more intense schedule of pesticides use.

Under conventional cultivation, sugar cane in Brazil it is the large culture that is less chemicals dependent, consuming annually less than 20% of the fertilizers and pesticides consumed by soybeans, for instance. The conventional culture, once planted, is kept producing for 5 to 6 years and, only then, is renewed. Organic cane areas are subject to renewing only each 9 to 18 years, with considerably higher yields. Furthermore, total area dedicated to sugar cane in Brazil, devoted to ethanol production, is still less than 1% of total culture and pasture available land.

Incidentally, I think the same organic cultivation techniques we use in Brazil for sugar cane could be applied in Hawaii (USA), Australia, India and many other countries, with particular emphasis in some countries of Africa, the ones I believe may become the best bioenergy exporters for Europe and Asia (I’m just working on this subject now), the same way Latin America may become an important bioenergy partner for USA and Canada. In regions where exists temperature, fertility or water restraints, organic methodology can compensate much of the difficulties found with conventional chemical cultivation.

EROEI is not all

It is my particular position to think that we cannot place EROEI in a sacred unarguable position for evaluating alternative energies. It is evident that, by no means, an EROEI value smaller than one is a good thing. But, in some particular cases, maybe even that could be tolerated for some time. As an example, I recall that, at the very beginning of Brazil’s ethanol large scale production for oil substitution, after 1975, the alcohol cost of production was more than twice the cost we have today. Also, in the seventies, ethanol was heavily subsidized and today there isn’t any kind of subsidies for it. In 30 years a spectacular change occurred: from heavily subsidized to not at all subsidized and with a large cost reduction, because of important gains in both cultivation and industrial processes. Since then, more than a million direct jobs have been created and maintained and more than 100 billion dollars have been saved from being lost as oil imports.

We must also consider that sugar cane and sugar cane ethanol industry is one of the least capital intensive and one of the more fast industries to install. In one year you can plant cane and build a distillery, starting to operate it in less than 1.5 years since starting point.

EROEI and costs for oil

EROEI is important in evaluation of economical costs, but that may be a somewhat limited concept, because I think is not safe to consider EROEI independently of TOTAL costs. In other words, it doesn’t help if we have a good energy yielding source per se, as oil, maculated by a very negative record of indirect and hidden costs. These hidden costs are an important part of the EI factor (the denominator) and, like that, they cannot be dismissed.

When we think of costs, we cannot think of economic costs only. We must consider the environmental and the social costs too. So, as our standard reference for EROEI is oil, there are three points to consider:

1 – Oil EROEI has been falling constantly with time, as lighter oils are extracted first and remaining reserves include mostly oils that are heavier, deeper and more difficult to extract. From figures as large as perhaps 100:1 we are arriving to 10:1 and even lower relations. So oil EROEI is not uniformly a high value. On the contrary, it is on the verge of becoming itself a worthless figure very near to one for a very large number of wells and whole fields in plain depletion, demanding absurd energy inputs.

2 – On the matter of SOCIAL costs, oil has a terrible roll of costs – most of them related to military and wars for oil and gas. And, also, related to the tyranny of automobiles, coming end of suburbia, rising prices of food, etc. For instance, the REAL cost of oil, for the USA, is much higher than officially admitted. When we internalize the military costs of oil wars and intelligence, the real USA cost of a barrel of oil is higher 110 dollars, not only 60+ dollars as nominally priced at present moment.

3 – In terms of ENVIRONMENTAL costs, oil has an even more terrible record: that of global warming, the most adverse of all risks humanity is facing this century. Not to speak of diesel fumes, tire dust (from oil most loved junior, the car), acid rain, spills, groundwater contamination and related evils.

So, IMHO, I believe EROEI, being itself different from cost, cannot be evaluated as an independent entity. To consider EROEI for oil, our dubious standard for evaluation of other alternative energy sources, in a context that takes economic, social and environmental costs in consideration, results in a more realistic evaluation that favors biofuels of high EROEI – like sugar cane ethanol in Brazil – very much.

Milton Maciel in Brazil

Follow what's happening in the Brazilian ethanol market on Ethablog, the only blog in English dedicated to Brazilian ethanol.

EUROPE TO COOPERATE WITH BRAZIL TO PRODUCE ETHANOL IN AFRICA

Via EthanolBrasil, BioPact,

BioPact, a very complete web site devoted to the development of a “green energy pact between Europe and Africa”, picked up several news items on Ethanol Brasil, a new site by leading Brazilian agribusiness consultant Marcelo Coelho that discusses the Brazilian ethanol and sugar industry, and produced a very interesting write-up.

BioPact reports that, “according to Brazil's ex-minister of agriculture, Roberto Rodrigues, the governments of the Netherlands and the UK will be financing ethanol production projects in Africa, and will rely on Brazilian technology and expertise to do so. This is a classic example of how so-called 'South-North-South' exchanges can unlock Africa's biofuels potential. Rodrigues speaks in his function as the coordinator of the recently established Centro de Agronegócio (created by the Getúlio Vargas Foundation, Brazil's leading social science foundation), which has taken up bioenergy as one of its main research areas.

Interestingly, the European governments in question are not taking the easiest route because they want to support the development of biofuels in some of the continent's poorest and most troubled countries. Rodrigues says that with aid of these governments, war-torn Sudan will be one of the first countries to be invited to Brazil on a mission to learn about ethanol technologies and production strategies.

The Centro de Agronegócio wants to become a leading consulting organization and will be networking in the Global South to spread Brazilian knowledge and experience with biofuel production. The Fundação Getúlio Vargas had already established a large body of expertise in the sector, but is now concentrating it in a 'biofuels intelligence centre'.”

The article continues on BioPact.

Follow what's happening in the Brazilian ethanol market on Ethablog, the only blog in English dedicated to Brazilian ethanol.