Get the Facts Straight: Organic Agriculture Yields are Good

Bill Liebhardt, 2001. OFRF Information Bulletin, Summer 2001, #10.

“When I returned to my office at the University of California, Davis, I began to gather scientifically replicated research results from seven major state universities: University of California, Iowa State University, Pennsylvania State University, Michigan State University, South Dakota State University, University of Nebraska and University of Wisconsin. I also looked into data from the research demonstration farm at Rodale Research Center in Pennsylvania and the Michael Fields Center at East Troy, Wisconsin on corn, soybeans, wheat and tomatoes grown under experimental controls for conventional and organic farming practices over the last 10 years.

“Since less than 1% of agriculture research dollars are spent on organic practices, I assumed it would be difficult for organic methods to compete with conventional practices in the yield category, in particular since yield is an over-arching objective of conventional research. But that is not what I found. Here are the highlights:

◆ Corn: With 69 total cropping seasons comparing high input and organically grown crops, organic yields were 94% of conventionally produced corn.

◆ Soybeans: Data from five states with 55 growing seasons of data showed that organic yields were 94% of conventional yields.

◆ Wheat: Two institutions with 16 cropping year experiments showed that organic wheat produced 97% of the conventional yields.

◆ Tomatoes: At the University of California, 14 years of comparative research on tomatoes showed no yield differences between conventionally and organically grown crops.

“In summary, for a total of 154 growing seasons for different crops, grown in different parts of this country on both rain-fed and irrigated land, organic production yielded 95% of crops grown under conventional high-input conditions.”
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Organic and Conventional Production Systems in the Wisconsin Integrated Cropping Systems Trails: I Productivity 1990-2002

J.L. Posner, J.o. Baldock and J.L. Hedtcke. 2008. Agron Journal, vol 100, issue 2, pp 253.

Abstract
During the last half-century, agriculture in the upper U.S. Midwest has changed from limited-input, integrated grain–livestock systems to primarily high-input specialized livestock or grain systems. Th is trend has spawned a debate regarding which cropping systems are more sustainable and led to the question: can diverse, low-input cropping systems (organic systems) be as productive as conventional systems? To answer this question, we compared six cropping systems ranging from diverse, organic systems to less diverse conventional systems conducted at two sites in southern Wisconsin. Th e results of 13 yr at one location and 8 yr at the other showed that: (i) organic forage crops can yield both as much dry matter as their conventional counterparts and with quality suffi cient to produce as much milk; and (ii) organic corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and winter wheat (Triticum aestivum L.) can produce 90% as well as their conventionally managed counterparts. Th e average yields for corn and soybean, however, masked a dichotomy in productivity. Combining Wisconsin Integrated Cropping Systems Trial (WICST) data with other published reports revealed that in 34% of the site-years, weed control was such a problem, mostly due to wet spring weather reducing the eff ectiveness of mechanical weed control techniques, that the relative yields of low-input corn and soybean were only 74% of conventional systems. However, in the other 66% of the cases, where mechanical weed control was eff ective, the relative yield of the low-input crops was 99% of conventional systems. Our fi ndings indicate that diverse, low-input cropping systems can be as productive per unit of land as conventional systems.
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