As the planet's population continues to grow, optimal crops need to be planted and harvested in order to feed people. One concern about widespread use of 'organic' cropping is that it would raise the price of food and have lower yields. Right now only rich people can afford organic food but if lower yields were worldwide only rich people could afford food at all, say critics.

It's not a huge issue, at least for some crops, say scientists at the University of Wisconsin-Madison and agricultural consulting firm AGSTAT. They say organic cropping systems are as productive as conventional systems for alfalfa and wheat and are almost as productive for corn and soybeans, according to research reported in Agronomy Journal.

In this research they found that: organic forage crops yielded as much or more dry matter as their conventional counterparts with quality sufficient to produce as much milk as the conventional systems; and organic grain crops: corn, soybean, and winter wheat produced 90% as well as their conventionally managed counterparts. In spite of some climatic differences and a large difference in soil drainage between the two sites, the relatively small difference in the way the cropping systems performed suggested that these results are widely applicable across prairie-derived soils in the U.S. upper Midwest. The researchers also compared their results to other data analysis done on this topic in the U.S. Midwest.

The researchers primarily based their answer on results from the Wisconsin Integrated Cropping Systems Trials, conducted for 13 years (1990-2002) at Arlington, WI and 8 years (1990-1997) at Elkhorn, WI. These trials compared six cropping systems (three cash grain and three forage based crops) ranging from diverse, organic systems to less diverse, conventional systems.

The cash grain systems were 1) conventional continuous corn, 2) conventional corn-soybean, and 3) organic corn-soybean-wheat where the wheat included a leguminous cover crop. The three forage based systems were 1) conventional corn-alfalfa-alfalfa-alfalfa, 2) organic corn-oats-alfalfa-alfalfa, and 3) rotationally grazed pasture.

Although researchers found that diverse, low-input/organic cropping systems were as productive as conventional systems most of the time, there is a need for further research, according to the study’s author Dr. Joshua L. Posner, University of Wisconsin.

“There continues to be improvements in weed control for organic systems that may close the gap in productivity of corn and soybeans in wet seasons,” Posner says. “On the other hand, technological advances may accelerate productivity gains in conventional systems that would outstrip the gains in organic systems even in favorable years.”

The true question of whether organic cropping systems are as productive as conventional systems is a dynamic question and one that requires continual reevaluation.

Article: Joshua L. Posnera, Jon O. Baldockb and Janet L. Hedtcke, 'Organic and Conventional Production Systems in the Wisconsin Integrated Cropping Systems Trials: I. Productivity 1990–2002', Agron J 100:253-260 (2008) DOI: 10.2134/agrojnl2007.0058