Friday, April 29, 2011

Organic Or Not?

Today’s post will review the effects of crop management system (organic or conventional) on several points of interest: productivity, nutritive content, groundwater contamination, pesticide residue, soil quality, and carbon footprint. The topics more closely related to organics in beef production will be covered in posts dedicated to antibiotics, hormones, and E. coli 0157:H7 (oh, my!) later.

1)      Introduction
First law of thermodynamics: energy cannot be created or destroyed, it can only change form. There is no such thing as low-input systems (commonly, organics) producing high outputs. While energy spent on conventional agriculture (such as that used in producing inorganic fertilizer) may change form in organic agriculture (increased labor for composting, manure and compost application, weeding, mulching), crops still don’t magically appear – it still needs soil nitrogen for growth (see post: “…Determined to Succeed!”), and nitrogen accumulation requires energy (carbon). Less cannot equal more.

Fuel vs. labor costs may in part determine the cost of conventional vs. organic production. More machines doing work at a lower cost means more people are free to choose an education, a profession, or a location of their desiring…then again, less people are receiving pay as farm workers…because less costly food is produced which is affordable for more people…thus, a dilemma emerges. Life is full of dilemmas in a zero-sum, no-free-lunch world.    

2)      Productivity
There is little argument that conventional agriculture produces more food per acre than organics. This means that, in a conventional system, more can be grown on less land—which is good, since only 25% of the surface of our planet is land. Take tomatoes for example: 1000 kg organic vine tomatoes = 122 square meters of land vs. 1000 kg conventionally-grown loose tomatoes = 19 square meters.

Studies consistently show that organic grain and soybean harvests are 20 – 40% less than conventional (not limited to…Cavigelli et al., 2007; Halberg and Kristensen, 1997; Mäder et al., 2002) Perhaps one or two years of organic cropping compared to one or two years of conventional cropping might produce similar crop yields (i.e., studies from the Rodale Institute, Badgley et al., 2006). These are the types of studies often cited by those who are pro-organic, but longer-term comparisons of both systems consistently show yield deficits (from 10 – 40%) within organic systems compared to conventional (Smolik and Dobbs, 1996; Shepard et al., 1996; Mader et al., 2002). Even one of the most pro-organic scientists of our time, Dr. David Pimentel, agrees that it has not been proven that organics can feed the world: “Avery et al. imply that I reported that all US and world agriculture could be grown organically without commercial nitrogen fertilizer. They are incorrect—I never said this in my review, nor have I ever said this in any one of the more than 500 scientific papers I have published” (2005). Remember that compost and manure does not really add to soil fertility, it maintains soil fertility by recycling, and it does so with diminishing returns. What does merit further study is the use of legumes (beans, alfalfa, clover…) to fertilize soils enough to replace synthetic fertilizer use, as Badgley et al. suggest (2006). 

3)      Nutritive Content
A meta-analysis (a study of 55 studies) concluded that there was no difference between organic and conventional produce in protein, antioxidants, Mg, Ca, P, K, Zn, Cu, and Vitamin C (Dangour et al., 2009). Another meta-analysis (on 45 studies) showed no human health superiority from an organic vs. conventional diet based on antioxidant status, breast milk composition, cancer cell proliferation, and other biomarkers (Dangour et al., 2010).

4)      Pesticide Residue
Part of the USDA organic certification process requires a 3 year withdrawal period from any unnatural pesticide use on farmland. If the neighboring farm uses inorganic pesticides and the wind carries its residue to the certified Organic farm, the organic farmer is held liable. Therefore, Organic produce will consistently have lower pesticide residues than conventional produce (Baker et al., 2002). Curiously, this doesn’t mean organic produce has zero residues. Some pesticides in use by the conventional systems and any pesticide used by organics will be biosynthetic (deemed safe at any concentration by EPA). All pesticide products bear a labeled statement that reads something like "For use up to ___ day(s) before harvest". This is the time period that is required for the compounds to deactivate and decompose into an EPA-deemed "safe" level. The EPA and FDA stringently regulate pesticide use and test produce for residues. Click here to see an example of a report. Pesticides include herbicide and insecticide. Herbicides are compounds that disrupt plant-specific processes. Herbicides will only affect you if you contain chlorophyll or can you produce your own essential amino acids (essential = can only come from your diet; Duke & Powles, 2008); if you possess these attributes, you should seek medical attention immediately. Certainly, the preparation and application of insecticides and fungicides can be dangerous, which is why I had to train for and obtain my pesticide applicator’s licence in order to purchase and apply industry- grade chemicals. There is less of a consensus about insecticides and other animal pest management compounds, especially for its effect on young children (NRC, 1993). However, no quantifiable evidence of short term or long term exposure to pesticide residue (within EPA/USDA tolerance levels) from produce demonstrates any deleterious effects on human health. Finally, everyone should wash their produce, regardless of its “organic” status, before consumption anyway.

5)      Bacterial Contamination
Organic foods are more at risk than conventional foods for bacterial and parasitic contamination because they rely on compost and manure to fertilize soil (Rembialkowska, 2007). Additionally, mycotoxins (poisonous fungi) are more apt to grow in organic crops because fungicide use is prohibited. On the other hand, Williams and Hammond (2001) found that there was a reduced risk in bacterial contamination within organic foods. Risk does not always translate into reality, of course. Organic farmers do well to aerate their compost to keep any harmful bacteria at bay. If you’ve never been worried about this before, don’t worry about it now, just keep washing your food like you always have. And please wash your hands. Food is no different than everything else in life that can transmit microbes.

6)      Groundwater Contamination
Per unit of food produced, phosphorus and nitrate groundwater loading were found to be the same for organic and conventional systems based on a meta-analysis by Mondelaers et al., 2009). Per unit of land, however, Mondelaers et al. (2009) found that organic systems usually have less nutrient-loading. Another study compared systems with equal land units and found that nutrient loading was the same regardless of organic status (Dufault et al., 2008). The point of either system is to produce food, so a pound of food as a functional unit provides the most valid comparison.

7)      Soil Quality
No-till systems using herbicide (conventional) are said to be the best at conserving soil quality (Soil and Water Conservation Society, 1995, as cited by Avery et al., 2005). Tillage required by organic systems increases soil erosion. However, soils in organic systems often have higher organic matter content since plant residues and manure are often added to the soil in these systems, displaying a positive effect on soil health (Mondelaers et al., 2009). Studies have been confounded by varying tillage practice within organic and conventional practices.

8)      Wildlife Biodiversity
Organic farming is positively associated with improvement in wildlife (wild and rare plants, more bugs, more birds up and around the field) compared to conventional (Mondelaers et al., 2009). Yes, pesticide abstinence tends to coincide with more bugs, more birds to eat the bugs, and more “wild plants”.

9)      Carbon Footprint
The differences between organic and conventional “carbon footprints” (fuel use efficiency) are unclear (Gelfand et al., 2010; Johnson et al., 2007) Certainly, no-till systems rely less on machinery (e.g., tractors, tillers…). However, organic systems don’t use synthetic fertilizer, which relies on fossil fuels for its manufacturing. The fuel efficiencies transportation of goods within either systems is highly variable as well. Presumably, then, taking food production as a functional unit, the conventional system may win out on fuel efficiency per unit produced. Too many confounding factors impede a sound conclusion as to which system is truly more “green.”

Again, what is sustainability: the ability to prolong the human population indefinitely; or, in other words, the ability to “feed the world” (which, of course, implies the responsible management of resources). In pursuit of this, shall we intensify what we can produce on less land by choosing conventional, thereby preserving land from cultivation? Or, shall we less intensely impact a larger land area with organic cultivation? Perhaps we can settle on this: we cannot conclude that either organic or conventional farming is absolutely superior to the other at this point. More likely, the two systems have much to learn from one another. What do you Think?


  1. I am curious about number 6. By ground water, do they mean aquifers or streams/rivers/lakes? If they mean aquifers then I agree that organic production would have less nutrient loading due to different forms of fertilizer (dry formulation applied by spreader vs. liquid formulations). If they mean streams/rivers/lakes then I disagree with their findings. The predominate form of fertilizer that is used in organic production is composted chicken waste. Most animal waste has a very high P:N ratio, especially chicken waste. In order for producers to apply the needed levels of nitrogen, they have to triple or quadruple the amount of phosphorous needed due to this high ratio. The excess phosphorus binds indirectly to the soil particles and is then carried off by run off (especially since organic production is at higher risk for erosion due to increased tillage). This runoff goes into the streams and causes hypoxic zones or "dead zones" that are very prevalent at the mouth of the Mississippi river.

    A combination of numbers 2, 3, 5, and 9 make it seem to me that it isn't worth it. Since there isn't any nutrition added to the foods, why would we want to use more land to produce less food and more pollution? The likely hood of pesticide contamination on food is very very small. Most chemicals are sprayed before the plant completes its vegetative growth before the reproductive growth starts. The few that are used after reproductive growth starts have very strict regulations on amount and timing of application. After the food are washed they are safe to eat. If any residue is left, the amount that is left on the surface would likely be far below the LD50 of the chemical. I would much rather have a chance of eating an EPA, FDA, and USDA approved pesticide than run the risk of eating fungal spores from something that could kill me and my family.

    As always, great post

  2. Good observation, Aaron. Mondelaers et al. (2009) studied nitrates and leached P within on-property surface water sites. The comparison between organic and conventional that the analyzed studies were making was really between low fertilizer input and high fertilizer input systems, and they state that "The main drivers behind the higher nitrate leaching in conventional farming are the larger amounts of fertilizer application, lower use of green cover crops, lower C to N ratio and a higher stocking density per [unit of land]." It's likely that high-yielding organic farms are responsible for higher nutrient runoff as you say.

  3. So they are comparing a garden to a commercial farming operation? I do not see how they can statistically compare the two if they used different levels of nutrition. The point of organics is to not use synthetically produced chemicals. They should have done a side by side comparison to the leaching potential and soil affinity of different fertilizers. I can see how their data could become confounded on this study very easily.

    Thanks for the update.

  4. For more information, view this web chat by Dr. Jude Capper done on May 11, 2011