Stopping Pollution with Pine Needles | Hacker News Reader

Stopping Pollution with Pine Needles

economist.com

36 pointslxm38 comments

In the southeast of the US longer pine needles from varieties of pines such as slash pine are used for garden mulch. Ironically, this was later in the season than I normally do this, I just laid down 52 bales of mulch in my garden.

Here it is common for a few reasons.

1. It is in-expensive (about $3.75 a bale). 2. It provides insulation to the plant roots to keep the soil warmer in the winter and cooler in the summer. 3. On steep inclines it tends to knit together to stay on the incline to prevent erosion. 4. As it breaks down it amends the soil with nutrients.

The only negative is that you have to add new mulch every year because it mostly breaks down after a year.

People who have pine tree farms use this as an extra revenue source. https://www.aces.edu/blog/topics/business-opportunities-fore... https://www.carolinacreations.biz/blog/mulch-and-pine-straw/

Is it heavy enough to keep strong weeds like Himalayan blackberry down? I would think they can break through a layer of mulch made of this (as opposed to wood chips).

If it is thick it will help.

Nothing short of Agent Orange can keep the Himalayan blackberry down. My neighbors put down 3" of gravel on a new driveway. Comes right back up.

If you've got a shovel, patience, and a decade of free weekends, you might make a dent... but probably not.

No shovels. Mattock. You don’t want to cut the roots, you want to get them all. For bad infestations: broadfork.

The trick with Himalayan blackberries is loosening the soil so you can dig them out more easily every time, Weed, amend, weed again.

Oh man - I wish I could have told my dad this in the 80s.

I got grounded when I was ~13 or so - and my punishment was to rake up all the pine needles on our 2 acre property in lake tahoe. The needles had created a blanket over the entire property which was ~3 inches deep.

It took me a month.

On a side note, same thing happened to me in the 90s. But instead of pine needles, it was a weed wacker and acres of waste high thistle weeds.

Oh yeah - and I was prohibited from the computer as well... So I couldn't play Populous or call into that BBS in San Jose to play the pit...

However, I topped this grounding:

I later called into a BBS in San Jose to play "the pit" and chat on PCLink so much that our long distance bill was $926 for a single month.

I was grounded for a month due to that.

My dad yelled at me a bit. Telling me that "computers will never do anything for you"

After I ran intel's game lab for a bit and designed the Lucas Presidio data center.... my dad said to me "remember that time I said that 'Computers will never do anything for you' -- Well, I apologize" - it was one of the closest times I felt to him.

How do you deal with the soil acidity?

You might want acidity. A lot of berry bushes like blueberries love soil down to pH of 4.0

Tomatoes like a more acidic soil as well.

Many flowers etc. in my beds prefer acidity. If it gets too acidic some lime can adjust things back.

> ... If it gets too acidic some lime can adjust things back.

You probably mean lye [1], which is alkaline to neutralize the acid.

[1]: https://en.m.wikipedia.org/wiki/Lye

Lime is alkaline, too, and cheaper:

https://en.m.wikipedia.org/wiki/Agricultural_lime

I thought limes are acidic.

Limes (the fruit) are acidic.

Lime (the fertiliser) is basically ground-up limestone and used to reduce soil acidity.

Pine needles aren’t actually that acidic, especially as they break down. It’s the turpenes that work as a herbicide.

The ground under a pine tree is its own little biome. It tends to be dry most of the year, which in addition to the other allelopathic chemicals, keeps things from germinating.

I have about 2 dozen lobblolly pines around my house. The needles definitely don't break down after a year naturally, god that'd be nice! Instead I end up with 4-8" deep 'drifts' of needles if I don't keep on top of things. And they are so waterproof they're incredibly difficult to compost - the inside of the stacks stays dry if you don't constantly churn them or shred them beforehand. We bag/bundle about 140 50gal bags of straw a year. I should sell them!

https://archive.is/t9qC2

Thanks!

So the secret is making charcoal with pine needles at 550 degrees.

Thank you.

From what I remember when I lived in the South every 5 cu yards of pine straw comes with a free copperhead, I wonder what they get in the Himalayas...

When you buy pine needles in bales? I’ve been spreading pine needles since I was 7 and not once have I encountered a snake in a bale of pine needles.

I think that's a joke. Snakes do like to hide out in loose pine straw.

Not in bales, more like when you know someone who knows someone who delivers it by the truckload. Usually they were babies.

I appreciate Pine trees even more now. I am in Canada and have access to many pine trees. One time I wanted to do a bit of soldering but could not find my flux. Small town had nothing anywhere near me so decided to see if I could make it. Quick DDG search shows rosin flux you can make from pine sap so I went to a tree, they all have gobs of sap dripping from some point, and collected some dirty sap. Took this home and soaked and stir it in pure isopropyl alcohol. Ran through a coffee filter and just let most of the alcohol air dry away. I love my flux it smells great works perfect and I know where that puff of smoke is coming from now. Felt rewarding as well 10/10 will keep doing this.

Interesting research, but utterly impractical. Are they proposing to harvest all the pine needles from all the forests in the Himalayas, convert them to charcoal and then use that to filter the Ganges? How much do they have to spend on this?

It's a fun mental exercise, but it's so far from realistic that it's funny.

Canadian here. Some areas of the forest are thick and dense and would be hard but the pine trees are a little higher up and not as much ground cover. You could in some areas quite easily gather pine needles. It would likely have to be done by hand but I can promise you this. There are lots of people who struggle to get by with no opportunity around here. But every year we get several months where chanterelle mushrooms grow and people head off into the woods to gather them. The buyers always pay cash so the people do not have to claim this money which is critical as most already collect social assistance and any money is just deducted from their check. So if pine needles have a value I could have people collect it for me.

And then you'll kill a thriving ecosystem that lives in those pine needles... including those chanterelles, matsutake and other (delicious or not) fungal species that live symbiotically with the trees. Not to mention the animals that live in the duff, and help prevent topsoil erosion.

In the boreal forests of north america used to be plentiful with "wizard's beard" moss. Hangs down from the trees, light and fluffy, made really good material for diapers. So we harvested it. All of it. Turns out these beards takes forever to grow, and similar mosses and lichens that contribute to a healthy forest take a hundred, or hundreds, of years to get established in new growth. I've seen wizard's beard in a couple of extremely remote places. But the industry died when they almost extincted it.

But yeah you're right. Loads of people will chomp at the bit to harvest this stuff. And you won't see chanterelles in the grocery story anymore. And after the topsoil is exposed in those woods, expect some intense fire seasons.

If you had read the article, you would know that pine needles are a leading cause of intense fire seasons...

Hence, harvesting pine needles could actually lessen the intensity of fire seasons, especially in drought-prone areas.

You'd be surprised what is realistic when the labor is pine needle cheap.

I wouldn't be surprised if you could pay some of the locals living there $5-10/day to collect pine needles, and have them end up better off than they are now.

Moreover, in western China the labor isn't cheap, it's free. (Uighur slavery)

Also, I'm pretty sure those pine needles are an important part of the ecosystem that has been inundated with them for thousands of years.

I can't imagine 6 tonnes of charred pine needles dumped in the Ganges effectively lasts more than a day for the purposes of heavy metal absorption. The math is beyond me, but it doesn't seem overly difficult. Especially when you consider that the needles don't show up all at once. They fall from the sky one at a time. After the first harvest, little Jimmy will be wandering through the once-lush, and now barren pine wasteland individually picking up pine needles with an eyebrow tweezer. It's interesting, but probably only "three legged dog" interesting.

You are also strip mining one biome to try to save another.

Interesting article, but I don't see the original research linked. There isn't much content here to say the effectiveness of the pinecones on the water purification. I was also confused with the 550 degrees vs 35 degrees comparision. I'd be curious to see if pine cones can have an impact on desalination as well.

Pine needles are great for scrubbing pots and pans if camping. But we don't do that. It might be green and practical but it doesn't happen.

The same with this story, great in principle but not going to happen. Pollution needs to stop at source and you need legislation and enforcement for that.

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