Organic Outperforms Conventional in Drought Years 

OLGA WICKERHAUSER, NJAES Sustainable Agriculture Coordinator / Plant & Pest Advisory 20nov03

Rutgers Cooperative Extension at the New Jersey Agricultural Experiment Station

Researchers at The Rodale Institute report that organically grown corn and soybeans significantly outyield their conventionally grown counterparts under drought. The researchers base this claim on data from The Rodale Institute’s Farming Systems Trial, which was started in 1981 and is one of the longest-running experiments comparing organic and conventional production in the world.

The trial compared two organic treatments – one based on manure and the other on legume green manures for fertility – to a conventional treatment where the main inputs were synthetic fertilizers and herbicides.

Organically grown soybeans and corn grown under the manure based organic system outperformed conventionally grown crops in each of the six drought years during the 21 years of the trial.

Yields of corn grown in a legume green manure system were higher than that of conventional corn in five of the six drought years. The only exception was in 1999, a year of extreme weather, when severe crop season drought was followed by hurricane Floyd’s torrential rains. In that year, corn grown after a legume cover crop yielded only one-third that of conventional corn. Researchers speculate the reason was that the hairy vetch cover crop used up what turned out to be most of the water the crops would get that year.

The study also found that the organic systems were more environmentally stable during the flood of 1999. The organic plots allowed less runoff and greater recharge of ground water.

In the trial, the researchers used a lysimeter placed below the plow layer to collect water in all plots. They found that, over a five-year period, water collected from organic plots was about 20% more than from conventional plots.

The researchers believe the higher yields in the organic treatments are due to the higher water holding capacity of the soils in the organic treatments, which received amendments of organic matter in the form of manure or legume green manures.

For more information, see the original article, which was published in the September 2003 issue of the American Journal of Alternative Agriculture (Lotter, D.W., R. Seidel, and W. Liebhart, 2003. The performance of organic and conventional cropping systems in an extreme climate year. American Journal of Alternative Agriculture 18(3):146-154.) Also, a detailed story about the research appeared in the November 7 issue of The New Farm (www.newfarm.org).

source: http://www.rce.rutgers.edu/ppa/2003/or1120.pdf 7jan04

Original research: Lotter, D.W., R. Seidel, and W. Liebhart. 2003. The performance of organic and conventional cropping systems in an extreme climate year. American Journal of Alternative Agriculture 18(3):146–154.