27 September 2013 22:30 [Source: ICIS news]
HOUSTON (ICIS)--Minnesota will unveil next week a plan that aims to substantially minimise run-off of nitrogen and phosphate into the Mississippi river and into the Gulf of Mexico, the Minnesota Pollution Control Agency said on Friday.
The state is one of 12 along the Mississippi river, the agency hopes area farmers can cut back on nutrients escaping into the Mississippi river, which eventually end up in the ocean, where it adds to the season hypoxic zone, frequently referred to a "dead zone".
Without revealing specific details of the plan until it is publicly unveiled, the agency said it has set as an objective to cut nitrogen releases from soil runoff by as much as 20% and phosphate by 35%. Officials said about 78% of nitrogen and 40% of phosphate found in the state’s primary rivers can be traced to crop fertilizers.
They said while area farmers are using less fertilizer per acre than in previous decades, the amount of land being utilised for crops has increased and has added to the overall problem.
When there is flooding events or excessive rains, which impacted the key corn growing regions this past spring, it leads to nitrogen-based fertilizer run-off into the river system and ocean waters. The released nitrogen encourages the rapid growth of algal blooms, which eventually perish and sink to the ocean floor where bacteria will decompose the organic matter.
At the same time the bacteria consumes the oxygen levels and thereby results in hypoxic, which is low-oxygen, or anoxic, oxygen-free, conditions. The dead zone typically appears in the summer as there is less mixing of currents.
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