Aquaculture for all

Report Looks Beneath the Surface of Hypoxic Zones

Water quality +1 more

MEXICO - A new analysis prepared for the National Corn Growers Association looks at some of the assumptions surrounding hypoxia low oxygen -- in the northern Gulf of Mexico and helps clarify the causes, effects and scope of the phenomenon.

“We’ve always known there were a lot of misconceptions about the hypoxic zone and its causes, based often on a lack of data,” said David Ward, chairman of NCGA’s Production and Stewardship Action Team, which funded the hypoxia report. “It is our hope that this report will help keep the discussion as grounded and data-driven as possible.”

In recent years, there has been a great deal of uncertainty related to the seasonal hypoxia in the Gulf, much of it giving the impression that the zone covers a large portion of the Gulf, the zone is permanent, hypoxia is caused by nitrogen and that nitrogen fertilizer applied to corn is the main cause.

In reality, the data do not support any of these contentions, according to Dr James McLaren, who researched the issue for NCGA. Dr McLaren is the founder and president of StrathKirn, Inc., a business consulting firm focused on new technology and emerging markets, ranging from primary agricultural production inputs to downstream value-chain impacts, biofuels and renewable resources.

"Complex natural phenomena, such as seasonal hypoxia in the Gulf, are seldom the result of a single cause,” Dr McLaren said. “Extensive analysis of the data across several factors indicates that there is no evidence relating modern corn nitrogen use with the occurrence of hypoxia in the Gulf. US corn farmers have applied new genetics and cultural technologies in such a way that there is now a net balance between nitrogen fertiliser input and nitrogen removed in the grain. If there is any nitrogen fertilizer from corn going down the Mississippi then it is most likely to be in a barge in the form of grain exports that contribute to the economy of the Midwest and the Gulf ports."

Dr McLaren’s analysis shows how the hypoxic zone is seasonal and, while localized effects can be severe, there are not “vast dead zones” that have widespread negative effects on the local fishing industry. On the contrary, it is possible that the Mississippi-Atchafalaya River Basin water flow delivers the basic nutrients required for the very existence of the northern Gulf fishing industry.

Fishing data from 1985 onwards suggest no negative impact nor any clear relationships between the fish catch, the flow of water through the Mississippi-Atchafalaya River Basin, or the size of the seasonal hypoxic zone.

One of the hallmarks of the McLaren research is that it shows how, in recent years, as corn production has become more efficient and yields have increased, the nitrogen removed from corn fields in the grain is approximately equal to the amount of nitrogen applied in the fertilizer.

“US corn growers have been focusing on efficiency as an important part of their traditional stewardship of the land and other natural resources,” Mr Ward said.

“Boosting yields thanks to technology helps us increase the number of bushels produced per unit of nitrogen fertiliser applied.”

Further Reading

- You can view the full report by clicking here.
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