hazelnut said:legumes. What kind? A mix?

Legumes are probably the easiest way to get nitrogen into the soil. But you should have some native plants, including trees, that are nitrogen fixers as well. They did a study here a number of years back and found there were around 50 nitrogen fixers that were native to our area. Quite a lot were trees.

There don't seem to be very many native nitrogen fixers -- to temperate US forests. The wax myrtle is one. http://www.mendeley.com/resear...

There are quite a few native to California and the western states.

Where there are introduced nitrogen-fixers they tend to have bad behavior. Like the Asian wisteria and mimosas in my yard.

And kudzu which blankets most of the forested areas in this part of Alabama.

That leaves legume ground covers, mycorrhizal fungi, and nitrogen fixing bacteria.

Many Elaeagnus species are also nitrogen fixing shrubs.

Also, Golden Chain Tree.

Golden Chain Tree (Laburnum anagyroides)

And very invasive. I don't know about golden chain, but I have eleagnus (silverberry) all over the place here. Another candidate for the Red Dragon flamer. It is highly invasive. I think there must be a correlation between invasiveness and nitrogen fixing properties.

No doubt about that. The N2 fixers are pioneers and designed to invade.

http://www.google.com/imgres?i...

Like a beautiful woman with evil intentions.

Nitrogen fixers are often the first to move back into disturbed ground. Acacia are some of our most common, they often take over along roadsides.

The tree that I am referring to as "acacia" is not really an acacia.

It is albizia julibrissin -- silk tree or mimosa. Not native to the United States, it is highly invasive in the Southeast. In fact, all of the invasives in my yard are introduced plants. The only native plants I have are some ancient pecans--the remnant of a pecan orchard planted some 120 years ago.

This is what the silk trees look like:

https://www.google.com/search?...

O.K. I know some permaculturists recommend using fitrogen-fixing pioneers, native or not. But how do you control them when they take over your property?

We have 223 species of Acacia in the Northern Territory, but only 57 in our immediate region. I like them, there are species for all situations, from swamps to desert sand dunes, from deep fertile to skeletal sandstone soils. And their leaves are excellent mulch. So they're good in the soil and on top of the soil. But as trees they're fast growing and fairly short lived. That does have its advantages in land rehabilitation. Pioneer plants are important, provided they don't cause greater problems further along. That's where natives (especially nitrogen fixers) have an advantage.

Mimosa (actual genus Mimosa) is another very bad invasive out of its natural habitat. We have huge areas covered by impenetrable Mimosa pigra scrub. Brought in as an ornamental originally, it got into the floodplains and took off. The seeds are viable for around 20 to 25 years. Eradication is a long slow process, and costly as well. Short sighted actions can have very expensive long term consequences.

Are you guys referring to growing these trees/plants in a permie setup, or using the wood in hugelkultur beds, or both?

We have several natives in AZ that known nitrogen fixers...many of those are legumes. Several varieties of acacia, cercidium (palo verdes), calliandra, ironwood, lupine, senna, and just about any mesquite of course. The only ones I might personally consider in a completely fabricated permaculture environ might be Chilean mesquite (which is not native), or a Honey mesquite. The beans can be used for flour, and the branches can be used for smoking meats.

Ah Hem! Well another source of nitrogen we flush everyday: urine.

I have a clump of garlic that my dog Roscoe cannot resist. I don't know if Ill ever be able to eat that garlic!

http://en.wikipedia.org/wiki/U...
Quote.

AgricultureMain article: Fertilizer
"Urine contains large quantities of nitrogen (mostly as urea), as well as significant quantities of dissolved phosphates and potassium, the main macronutrients required by plants, with urine having plant macronutrient percentages (i.e. NPK) of approximately 11-1-2 by one study[20] or 15-1-2 by another report,[21] illustrating that exact composition varies with diet. Undiluted, it can chemically burn the roots of some plants, but it can be used safely as a source of complementary nitrogen in carbon-rich compost.[22]

When diluted with water (at a 1:5 ratio for container-grown annual crops with fresh growing medium each season,[23] or a 1:8 ratio for more general use[22]), it can be applied directly to soil as a fertilizer. The fertilization effect of urine has been found to be comparable to that of commercial fertilizers with an equivalent NPK rating.[24] Urine contains most (94% according to Wolgast[20]) of the NPK nutrients excreted by the human body. Conversely, concentrations of heavy metals such as lead, mercury, and cadmium, commonly found in solid human waste, are much lower in urine (though not low enough to qualify for use in organic agriculture under current EU rules).[25] The more general limitations to using urine as fertilizer then depend mainly on the potential for buildup of excess nitrogen (due to the high ratio of that macronutrient),[23] and inorganic salts such as sodium chloride, which are also part of the wastes excreted by the renal system. The degree to which these factors impact the effectiveness depends on the term of use, salinity tolerance of the plant, soil composition, addition of other fertilizing compounds, and quantity of rainfall or other irrigation."

. . . quote continued under Agriculture at the link.

And I've been flushing that stuff every 2 hours.

Can you tell me if urine, particularly dog and cat urine, is high or low PH? I'm assuming it is fairly acid, thus I've not discouraged the cats and dogs from peeing on some of my acid loving beds although I do dilute it fairly quickly. It's hard to grow acid loving plants here as the soil and the water are very alkaline, I live on a limestone shelf. I also put coffee grounds and such on the plants but I'm hoping the animals are helping too.

As urine breaks down it makes ammonia which has a high pH. These sorts of things are better put through composting, but it can be difficult to train your animals to use the compost heap.

Extranjera:

Here's what the wikipedia article cited above says about the pH of urine: Quote:

pHThe pH of urine is close to neutral (7) but can normally vary between 4.6 and 8. In persons with hyperuricosuria, acidic urine can contribute to the formation of stones of uric acid in the kidneys, ureters, or bladder.[13] Urine pH can be monitored by a physician[14] or at home.

A diet high in citrus, vegetables, or dairy can increase urine pH (more basic)[dubious – discuss]. Some drugs also can increase urine pH, including acetazolamide, potassium citrate, and sodium bicarbonate.[citation needed]

A diet high in meat can decrease urine pH (more acidic).[citation needed] Cranberries, popularly thought to decrease the pH of urine, have actually been shown not to acidify urine.[15] Drugs that can decrease urine pH include ammonium chloride, chlorothiazide diuretics, and methenamine mandelate.[16][17] Unquote.

Apparently meat eaters, and/or carnivores would be more likely to have acidic urine.

Our soil back home in Northern Michigan are glacial soils and also quite alkaline. I think however in a natural forest there will be a variety of soils, depending on the plant cover. I remember wintergreen berries only grew in the pine straw under pine trees. They require a fairly acid soil.

So if you have a source of pine straw you might use it to acidify some soil for your acid loving plants. Peat moss can also be used, but it is quite expensive now-a-days.

Here in the tropics, pine straw is pretty rare There are some tropical trees that resemble northern softwoods but not many.

I do add peat moss once a year to all the beds after the rainy season, mostly because we get such torrential rains that it washes a lot of the soil right down through the limestone. I feed my cats and dogs mostly meat so perhaps it is helping. I can't mulch the beds because it provides a great breeding spot for mosquitoes. Thanks for the good info.

Thank you all for the info. I am planing to make raised beds with Hugelkultur soon, and we have next to our house an abandoned property, full of acacias, which we will have to prune a lot, so I was checking, if I can use the branches in the beds. Have a good year everybody 😃👍😉

Extrangera, if mulch for your beds were innoculated with beneficial bacteria that fed on mosquito larvae, couldn't you have mulch without mosquitos? I'm thinking of a product I've used very successfully against gnats and mosquitos, called Mosquito Bits (bought from Amazon). It comes in a granular form, and a very little bit goes a long way. I was just wondering how this would work for your climate.