Hacker News Reader

Comment by jimkri | Hacker News Reader

I think there is a huge opportunity to use Seaweed or Algae for fertilizer.

Theres ways to do this on each coast but also to utilize the Pig and Cow farming waste to not only clean water in the process but to take major waste producing industries and try to soften their impact.

I think the more people that know about the use cases of Seaweed and Algae will help that industry come back. There were too many companies that only saw Algae as a way to make bio fuel. I see it as a way to clean dirty water, and to produce a bi-product that can go back into the ground.

I also think theres a way we can just use the warmer waters and the over production of seaweed, like the gulf coast especially closer to Mexico. So much seaweed is scrapped from the beaches but never used at scale for production

View on HN

For some small freshwater lakes, they participate in "weed harvesting" to keep waterways navigable and reduce "nutrient load" to the lake which can trigger algae blooms. The "weeds" are various forms of aquatic plants (e.g. Eurasian watermilfoil) which get removed and often transported to local farms for use as fertilizer. This isn't a very widespread practice, but has been included in education from state-level DNRs.

We could create fertilizer from sewage. I didn't see a lot of details in that article as to what they were going to use to create said fertilizer - only that there was a 'sustainable' bullet there. Sustainable implies not using fossil fuels, I would think.

It depends on what is used to clean the sewage, but I think theres a couple ways to make fertilizer from it. Depending on the animal or type of sewage, if you use duckweed or algae to clean the water you can take that and apply it to fields. You will also have the sludge from the sewage that can also be applied directly to fields. Pig farmers will usually take some of the sludge from their lagoons and apply it directly to their fields, and they will also spray a watery-sewage on the fields. I don't like this method since its proven to travel by air and also can contaminate water tables at high levels

But if the water is high in metals and other toxins you can only do so much with the excess from this process

Can salt-water-grown seaweed be used as fertilizer? I'd suspect that it would require significant amounts of fresh water processing to remove the salts or else it could hurt the plants.

I found a local business that was turning seaweed into fertilizer and he was letting the seaweed dry out and then grinds it up and bags and sells it. I'm not sure if the drying of the seaweed will get rid of the high sodium, but that was my first thought is the amount of work that will have to go into cleaning it.

There also can be other fish, and debris that can get stuck in large patches of seaweed. So that would have to be filtered out as well

I've read rotting fish can be great for gardens... maybe the quantity of fertilizer needed is low enough that salinity isn't a major issue.

I have seen people set up clear tubes w/ water as "algae generators" to create diesel, and also to create fertilizer for their gardens

I don't think there is enough to scale that way. I'm also not sure if there are ecosysytem concerns from taking it from the sea and moving it to the midwest. I have no idea how seaweed will affect soil long term. That said, within the limits of the above by all means use it. Just don't pretend it is an answer along.

Yeah honestly I think there would be too much processing involved to make it realistic.

The benefits of Seaweed to soil (ignoring salt and sand) has been proven to help bring key nutrients and metals to the soil that are missing from farm land that was used for single plant production.

It will be easier to just add those elements directly as chemicals.

Depends on the element that needs to be added, seaweed has the benefit of being a weed that can grow in the right conditions very fast.

And seaweed will have the drawback of being an extremely dilute source of trace elements. Consider iodine. Seaweed is rich in iodine, which means the concentration of the element can be as high as tens of ppm by mass. Which is cheaper, applying 1 kilogram of iodine (cost about $30) to a field, mixed in with regular fertilizer, or transporting and applying tens of tonnes of seaweed?

Seaweed is already a fertilizer and used around the globe. It's no different then decomposed lettuce or any other leaf vegetation, it just grows underwater.

Reply on news.ycombinator.com