Environmental, Energetic and Economic Comparisons of Organic and Conventional Farming Systems

Summary of Selection 29


Our agricultural system depends heavily on synthetic chemical fertilizers, pesticides, and herbicides, which have negative public health, environmental, and economic effects. Some of these are contaminated streams and groundwater, huge health care costs ($12 billion/year in the US), nutrients from the fertilizer and manure destroy water ecosystems, soil erosion and more. Certified organic agriculture with integrated pest and nutrient management will reduce reliance on chemicals while helping the environment and remaining economically sound. Organic agriculture uses ecological processes to help plants grow while conserving soil and water.


An experiment was done to compare organic and conventional farming. 3 cropping systems were used:
1) Conventional cropping- synthetic fertilizer and herbicide use
2) Organic "animal-based" cropping- used animal manure as nitrogen source (fertilizer), no herbicides
3) Organic Legume based- used a nitrogen fixing legume crop for fertilizer, no herbicides

Crop biomass, weed biomass, grain yield, nitrate leaching, herbicide leaching, percolated water volumes, soil carbon, soil nitrogen, and soil water content were measured and compared. Generally, results were very positive for the organic methods. Yields under a normal rainfall were close to the same for all methods (after a 5 year transition period), and under drought conditions the organic methods produced higher yields (due to increased groundwater recharge, decreased runoff and increased soil water content.) Some field tests from Europe and New Zealand indicate a 30-50% decreased yield using organic farming. This could be due to low nitrogen-nutrient levels; although during the first few years of the Rodale study the yields were lower too (transition period). In the long term there should be no difference- providing crop legume rotation and manure fertilization is done properly.

Crop yields and economics of organic systems do vary based on crops, regions and technologies used. However, the environmental benefits are much greater in organic systems. Reduced chemical inputs, decreased soil erosion, water conservation, increased soil organic matter and biodiversity, reduced crop diseases, increased microbes within the soil, decreased oil and natural gas inputs (helping to prevent climate change) are some of the many environmental benefits. There are also economic benefits. Organic produce can sell for 20-140% higher in many countries across the world. Labour inputs are higher than conventional farming, but are more evenly distributed throughout the year allowing for more regular/dependable income for workers.

Some challenges are the it can be difficult to maintain soil fertility (nitrogen levels). The results of the Rodale study may not be universally applicable. Pest and weed control can also be difficult. These difficulties inevitable affect yields negatively. To make adoption of organic farming easier we would require increased knowledge/technology to help. Off season cover crops and extended crop rotation would be needed. We can use natural biodiversity to reduce the use of chemicals (even if it is just slight decreases at first). There are many benefits to organic farming that seem to outweigh the difficulties that may be troublesome at first as we work out the kinks of the method...organic farming is more sustainable and ecologically sound!