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Attack of the Blue-Green Algae and How to Slow the Blooms

Published by Soilutions on

If you did not know, August is National Water Quality month.  As New Mexicans we are all acutely aware of the importance of water, but we are not immune to the blissful ignorance of water quality issues that impact our local environment, at least not until there is some major event the headlines to draw our attention. In 2015 the Gold King Mine spill into the Animas River caused incalculable environmental damage to Navajo Nation and farms in the northwest corner of the state. This year we are seeing another preventable, or at least containable, water quality issue rise up: Toxic Blue-Green Algae brought on by nutrient pollution.

Blue-Green Algae, or cyanobacteria, recently forced a closure of Abiquiu Lake and is currently being monitored and tested in Elephant Butte, and the season is only beginning.  Blue-Green algae is naturally occurring, most blooms are not toxic, but the frequency of blooms is increasing and with it the threat of toxicity. Currently there is no government organization monitoring toxic algae blooms, but one organization, the Environmental Working Group, has taken on the task since 2010. While there are no reported human deaths associated with toxic blue green algae in 2019, there have been multiple reports of dogs and pets dying from toxic blooms in lakes, streams, ponds and reservoirs. 

Even though algae blooms are naturally occurring, the frequency and intensity of them are not.  Algae feeds on nitrogen and phosphorous, both of which occur naturally, but the major blooms are encouraged by external forces in the form of surface runoff.

Surface runoff is problematic in New Mexico because of our limited rainfall and nearly constant sunshine bakes the ground until it is essentially as hard as concrete.  When the soil gets to this point it becomes hydrophobic, meaning it repels water. You have probably seen it in your yard: you water until puddles form and they are still there an hour later, or the water just drains off your yard onto the sidewalk and down the storm drain, taking with it all the plant food and nitrogen rich grass clippings. Soil can become hydrophobic in just a few hours during the driest parts of summer.  

Runoff can also occur when fully saturated soils are over-watered and, more likely in New Mexico, when heavy rain events such as monsoons release more moisture than the ground can absorb.  Surface runoff from over-saturation contains the eroded soils from gardens, small farms and large agricultural fields.  These soils can be particularly harmful to our water ways because of one thing: over-fertilization. Over-application of fertilizers on agricultural land is the world’s biggest source of water pollution.  

Currently there is no regulatory body that evaluates the levels of nutrients in agricultural fertilizer applications. This problem is compounded with the fact that none of the Departments of Agriculture around the nation have maximum limits on nutrients in fertilizer. The regulatory commissions set up by DoA’s only verify the claims on packaging or the “guaranteed analysis” meaning the 1-2-2 NPK fertilizer you buy could contain 20% nitrogen 40% phosphorous and 40% potassium. As long as the minimums are met for the label, the actual values are unknown without costly lab tests. Consumers of these fertilizers are unaware of the nutrient pollution they are contributing to. The lack of regulation, and unethical labeling, is part of the reason we see nutrient runoff levels reaching such disastrous levels. 

Another reason for over-fertilization of agricultural lands is more basic. Economics. The economic factor is relevant for a multitude of reasons, but it is also the easiest to comprehend.  It’s cheaper and more efficient to use chemical fertilizers for maximum short-term gains. As any organic, sustainable farmer or gardener knows, developing and maintaining a healthy soil is key to crop yield and a huge investment in time and money. It is easier and cheaper to provide artificial nutrients to depleted soils than to develop a functioning soil ecosystem.  In the short term. The long-term economic effects of water pollution are yet to be fully realized, but hints of them are just coming to the forefront.

Industrial Chemical Fertilizer Application

Chemical fertilizer applications also contribute the general land degradation, increased erosion, and loss of biodiversity in more than just the immediate landscape.  When large scale farms plant their fields they generally do not replenish their fields. With modern technology we have managed to avert any crisis similar to the dustbowl of the 1920’s, but better technology does not lead to better practices.  Overplanting the same fields year after year leads to natural nutrient deficiencies and the need for increased fertilizer use to keep the land economically viable. The depleted soil is more apt to erode and take with it the unabsorbed fertilizers, namely nitrogen and phosphorous, and deposit them in ponds, lakes, streams, and rivers and eventually the ocean.  The nitrogen and phosphorous feed the blue green algae that then blooms in its’ new nutrient rich environment.  Algae blooms rob the water of oxygen, creating dead zones in which no aquatic life is sustainable. There is a dead zone in the Gulf of Mexico the size of Massachusetts, attributed mostly to the fertilizer runoff into the Mississippi River.

Map of the dead zone in the Gulf of Mexico

The Path Forward

The Environmental Protection Agency has set out to monitor waterways and to establish and develop state by state criteria for measuring nutrient pollution, but these are reactive measures to a situation that needs proactive solutions. The most efficient way to combat nutrient pollution is to utilize sustainable agricultural methods on all crop land and farms. 

Adding compost to soil replenishes nutrients naturally, helps aid the creation of a healthy soil ecosystem, and acts as a natural filter for pollutants.  A well-balanced compost works in unison with the plants it is providing for. Think of compost like your refrigerator; it stores the food plants need until they need it. On the other hand, inorganic fertilizers applied over depleted soils only give the plants what they can eat at that moment, leaving the leftovers to wash down the stream. Compost is essentially living culture, adding life to the existing soil and providing an environment for beneficial bacteria and fungi to thrive.  These bacteria and fungi are able to consume, transform, and store potential pollutants, all things an inorganic fertilizer cannot do.

Using compost instead of raw manure or chemical fertilizers, nitrogen fixing crops, crop rotation and companion planting are just a few ways to implement more sustainable practices in the field. At home you can use local compost in the garden, start a worm bin or get chickens to produce your own compost base, and buy fruits and vegetables from farmers you know to use sustainable practices. 

In honor of National Water Quality Month call your legislators and ask them what their plan is to combat water pollution. Here in New Mexico water is our most precious resource, we cannot afford to poison it.
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