SCIENCE LITERACY WORKING WITH DATA

The data in the following graph come from the Farming Systems Trial® (FST) research study conducted by the Rodale Institute. This side-by-side comparison of corn and soybean crops grown under organic and industrial agricultural systems was started in 1981 and is one of the longest-running studies of its kind.

Interpretation

Question 17.15

What does this graph show?

It shows a comparison between organic and conventional agricultural systems for yields, profits, energy input, and greenhouse gas emissions.

Question 17.16

Calculate the following for conventional and organic systems: profit per unit of yield, energy input per unit of yield, and greenhouse gas emissions per unit of yield. How do the two systems compare on these three parameters?

a. Profit per unit of yield:

Organic — 558 / 4079 = 0.14 $/lb

Conventional — 190 / 4022 = 0.05 $/lb

b. Energy input per unit of yield:

Organic — 3264 / 4079 = 0.80 MJ/lb

Conventional — 4568 / 4022 = 1.14 MJ/lb

c. Greenhouse gas emissions per unit of yield:

Organic — 906 / 4079 = 0.22 lbs CO2/lb

Conventional — 1400 / 4022 = 0.35 lbs CO2/lb

For all parameters, the organic system outperforms the conventional system. Per pound of food production, the organic system produces greater profit while it uses less energy and produces fewer greenhouse gases.

Advance Your Thinking

Hint: To answer the following questions, it might be helpful to access the actual FST report, at http://rodaleinstitute.org/our-work/farming-systems-trial/farming-systems-trial-30-year-report/.

Question 17.17

According to the Food and Agricultural Organization of the United Nations, “Organic agriculture has the potential to secure a global food supply, just as conventional agriculture does today, but with reduced environmental impact.” How do the data from the FST study support this statement?

The data from the FST study shows that organic agriculture has yields that are equivalent to conventional agriculture—4,079 lbs/acre/year for organic as compared to 4,022 lbs/acre/year for conventional—supporting the FAO claim that organic can “secure a global food supply, just as conventional agriculture is today.” In addition, the FAO’s expectation that environmental impact of organic systems are less than the conventional system is also validated as the data from the FST study show that organic systems use less energy (3,264 MJ/acre/year) than conventional (4,588 MJ/acre/year) and produce less greenhouse gases: 906 lbs CO2/acre/year for organic as compared to 1,400 lbs CO2/acre/year for conventional agriculture.

Question 17.18

According to the FST report, even in drought years, the yields for organic corn were approximately 31% greater than those for conventional (non-drought-resistant) varieties. At the same time, genetically engineered drought-tolerant varieties had yields that were no more than approximately 13% greater than conventional (non-drought-resistant) varieties. Why might this be the case? Why is this an important finding?

There are two main reasons. First, in organic systems, farmers typically use seed grain that is locally adapted. This means that just like the genetically engineered drought tolerant varieties, the organic seed would have natural drought tolerance giving the GM seed no advantage. Second, the soil in organic systems is much healthier — they tend to be rich in nutrients and microbial life, stay in the field rather than erode, and provide a stable and consistent environment for the plants to grow despite weather conditions.

This is an important finding, as in the face of global climate change and the unpredictability of future weather it suggests that organic agriculture can still produce food without significant loss in yields.

Question 17.19

The FST report indicates that crops grown using organic methods produced yields equivalent to those of conventional crops, even though they had more weed competition in their fields. Why might this be the case? What makes this an important finding?

Again the reasons are likely related to the organic practices and the health of organic soils. Since organic soils do not erode as easily and tend to have higher nutrient content, they likely can support both the weeds and the crop yields. Furthermore, organic crops are likely better suited to grow in weedy environments and not be out competed by weeds in accessing the nutrients they need.

This is an important finding as in the face of the increasing number of herbicide resistant weeds, it suggests that with organic agriculture we can still produce food without significant loss in yields.