About phosphorous (where to begin?)

This is my first post.

I live in a hilly neighborhood of East Los Angeles (near the Arroyo Seco).

My landlord built an amphitheater like garden plot (concrete perimiters) descending down a small hill, partially shaded by huge guaje trees (Leucaena leucocephala. It hadn’t been gardened for years before I moved in.

Last year was our first go. We found found worms, coffee grounds, and covered the beds with sycamore leaves in the Fall. In the Spring we planted many types of vegetables: kale, and leafy greens, beets, radishes, and later squash, tomatoes, peppers...

Since then I’ve become much more interested in learning about the soil. I tested our soil for PH and NPK. PH is 6.5, nitrogen is ‘sufficient’, phosphorous ‘depleted’, and potash ‘deficient’. Our soil is fairly dense, with some sand.

I’ve been looking for an organic and sustainable source for phosphorous and potassium. Though I originally wanted to opt for rock phosphate/greensand, after more reading it seems like not the right direction environmentally speaking. I then thought bone meal (for P) would be best, though one of my friends from the garden doesn’t like the idea of bone or supporting meat industry in any way (even if it is a waste product)... It seems to me though that phosphorous is really only either rock or bone by nature, or a much smaller amount taken up by a plant. Which leads me to a more specific question: how much phosphorous do I really need if our soil is ‘depleted’? Vegetables seemed to do fine last year, though perhaps some issues with lack of largesse, insects... Would using something like barley meal provide sufficient phosphorous? Any suggestions?

I know there is so much going on in the soil beyond simple NPK; like how available are these nutrients actually becoming to the plant. I’ve also become fascinated with idea of sea water/minerals and bokashi... though I’ve tried neither. Anyway, we’re looking for some simple sustainable amendments to begin with. Any thoughts?

Thank you,

Daniel

Manure is your best source of phosphorus and potassium if you're looking to get sustainable nutrients. It might not be possible for you to spread it but if that is the case, a well done compost will also work. There might be some farms around that do their own composting although I know little of the area you live in. If there are any smaller horse farms around, they usually either compost or offer their manure for free because it's too much work for them to spread it. The horse manure will take longer to have an effect because it is lower in those nutrients than a ruminant or poultry manure.

In general insects are more likely to attack weaker plants, those that aren't getting enough phosphorus and potassium will be weaker.

Kelp from the beaches when dried and ground up works well as a soil conditioner, as Natasha brought up cow manure, sheep manure, chicken manure are all really good for P & K, if you got kelp and some manure(s) and mixed them together you would have a great amendment to use either as a soil feeding mulch or as a turned into the top few inches amendment.

Redhawk

Thank you for the suggestions. This is what I’m looking for.

My friend works with horses, I may be able to get some but then yes I’m not sure if I’ll be able to break it down... Is poultry much preferable? From what I read P seems to be higher (our P is pretty low).

I can probably find some kelp too. How would one go about grinding kelp?

I’m also interested if you would recommend sea water also.

Thank you again

Sea Water is something you can do several times in a season, the water down around Palo Alto is really mineral rich, not so much so in L.A. Bay.
I've ground kelp in food processors with good results from pulsing about 20 times,

Horse manure breaks down nicely once it has aged about a month (do that in a bucket with some cheese cloth over it if your in a city situation).
Poultry manure is "hotter" than horse manure and it is also hotter than cow manure, this requires it to be composted prior to use in the ground.

Just reading up on manure. We were hoping to start planting in a couple of weeks. My friend has access to horse, chicken, goat, and rabbit manure but now I’m thinking about pathogens...

My friend works with horses, I may be able to get some but then yes I’m not sure if I’ll be able to break it down... Is poultry much preferable? From what I read P seems to be higher (our P is pretty low).  

As far as manure goes, you do want to be careful with the higher nutrient manures and when you apply them. Some actually are too high for direct application to a soil with plants and will burn the plants. This is because of high nitrogen. Poultry manure is pretty bad about this unless it is pelleted, which you might have some luck finding in stores.

I wouldn't try and apply a ton of manure in the first year to get your levels up fast. There's some risk of plant burning and you may over apply. Some crops also don't need a ton, leafy greens, etc. If you apply too much and then grow tomatoes, the plants will grow enormous because of excess nitrogen but produce little fruit.

If you have a fallow/not growing season (it looks like fall for you), apply the manure of any sort then, mix it into the soil, and the soil microbes will get to work breaking the manure down and storing it in stable forms in the soil. This will prevent burning. If you do the horse manure, you can apply a greater amount ahead of time and it will breakdown in the soil just fine. You may need to add some moisture depending on your climate.

One thing I did with a small garden a few years ago is I dug the area where I was going to grow potatoes a month ahead of planting and buried the horse manure under the ground by six inches under my potato planting trench (I was double digging). By the time the potatoes got big enough to reach down there, the manure had broken down very well and provided nutrition to the plants. I had lovely potatoes that year.

So overall with manure, apply and mix in ahead of time. Pig, and poultry manure tend to be "hot" in nutrients and need more time to stabilize before plants go in on it. Horse, dairy, cattle manures and pelleted poultry are less hot, need less time/no time before planting into them but provide less nutrients.

Thank you Redhawk, I just saw your post. Great to know about the sea water.

Maybe we should consider buying precomposted manure.

Hi Natasha, thank you for that info. It looks as though if we start right away we’d best use aged/composted manure tilled in with the soil. Or ditch composting the manure beneath plants as you suggest.

As I understand it, for greens we don’t need as much phosphorous, so perhaps we could start with those and let the manure compost in beds for flowering plants later.

I have given a lot of info on composting in my soil threads the epic soil threads

edit, forgot to mention it but the start of the book is now available thru a link in the soil threads list (the last entry)

Bryant RedHawk wrote:I have given a lot of info on composting in my soil threads the epic soil threads

edit, forgot to mention it but the start of the book is now available thru a link in the soil threads list (the last entry)

I very much appreciate your help. I started digging into your soil threads last night. Will definitely look into your book!

Burn some bones to char them (about 200g)

Dunk them into 1 litre of vinegar.

Wait for 7 days and strain

The liquid is water soluble calcium phosphate.

Dilute this to 1:500 - 1:1000

Spray on leaves when the fruits are ripening or leaves are about to be harvested.

Crush and burry the bones in soil