Crop Biodiversity a Cure for Ocean Dead Zones?

Farm Biodiversity Crop Reduce Nitrogen Runoff Photo
Migrated Image

Photo Nicholas_T @ flickr

Biodiversity is the variation of life within any system. High biodiversity is a trademark of ecosystems that are healthy, resilient to stress, and those that provide valuable ecosystem services like clean air, water, or food. Yet, when we farm, increasingly, we seem to plow under the diverse ecosystem and plant a monoculture (single species) in its place. The results lead to increased soil runoff, higher fertilizer requirements, and ocean dead zones. But there is a rather simple solution...

Ocean Dead Zone Nitrogen Runoff Image

image NASA
Industrialized Farming Leads to Ocean Dead Zones
New research out of Louisiana State University shows that planting strategies that include a diverse range of crops is a technique that could lower nitrogen runoff. The study points out that where biodiversity of crops is high, there is less dissolved nitrogen found in the surrounding watersheds that eventually make it to the ocean. Nitrogen from agriculture fertilizers (produced from fossil fuel) winds up increasing the local aquatic dissolved nitrate. The increased nitrate leads to the growth of algae, which uses up the available oxygen in the water, creating dead zones.

Ocean Dead Zone Nitrogen Runoff photo

image US DEP

The number of marine dead zones has doubled every 10 years since the 1960s, which corresponds nicely with the increase of these industrialized farming technologies.

Smaller More Diverse Farms Could Enable Ocean Recovery
Whitney Broussard and R. Eugene Turner gathered watershed and land-use data from the past 100 years to get a better picture of the factors that are at play. The results show that the average farm size has gone from 60 ha in 1900 to 180 ha in 2002. The paper didn’t fail to mention what we have reported on before, that corn farming for ethanol using management practices such as commercial fertilizer application, mechanical tillage, and intensive drainage is the most important driver of this increase in nitrogen pollution.

"These results are important because they highlight the need to address land use in order to reduce both the size of the low oxygen zone off Louisiana and the negative effect of nutrients on coastal wetland restoration efforts," said Turner.

"With the growing American farm comes the necessity to use more industrialized means of farming," said Broussard. "Our agricultural practices have always impacted water quality, but over the past century the mechanization of agriculture and the use of more potent fertilizers has caused a greater effect: the nitrogen leakage rate is higher.... Diverse farms tend to have smaller fields with more edges, which can mean there's a greater buffering effect on nitrogen runoff by surrounding grasslands or woodlands."

The good news is that the impacts of nitrogen pollution due to industrialized farming practices might be reversible if incentives were developed for farmers to increase biodiversity, decrease field size, increase buffering zones, and incorporate more native landscapes between fields.

"There has been great progress made to reduce the footprint of agriculture, but there is still room for improvement," said Broussard. "The American farmer is caught in a mode of production that has tremendous momentum and cannot be changed on the farm – it's a policy question now."

via LSU News