OK
First, you can buy inoculant for commonly planted legumes. Indeed, peas do not associate with the same bacterium species as clover. There may be differences among clovers. Peas, vetch, broad beans, lentils--they all are compatible with one species of inoculant.
For ordinary garden crops, you can usually buy for a few dollars a mixture of nitrogen fixing bacteria in ample quantities. In California, you'd likely use Peaceful Valley Farm Supply for your inoculant. Their catalog usually has a table showing the inoculant to use for a given species. A more comprehensive table can be purchased from Agroforestry Research Trust in the UK. I rely on it.
Usually, the garden mixture does not include soy inoculant. You need to buy that separately. Naturally, you would not find that inoculant in the wild unless you went to Japan (and probably China).
Lupin inoculant is hard to find.
To harvest inoculant in the wild, dig up the wild legume and see if the roots have nodules. If so, cut them open and see if they are pinkish inside. If so, you have an effective nitrogen fixing strain and you should take a batch of the roots home. You don't need to dig up the field, a few handsful of inoculated roots will suffice.
Put them in a blender with some finished compost and plain water (not tap water if it is treated) and blend. Swirl a bit of this in a shallow pan with your seed and it will all be inoculated. Plant immediately. Keep the extra in the refrigerator (not the freezer) until you have no further need. Sometimes you can buy a plant from a nursery. For example if you wanted Caragana inoculant, you might buy a single Caragana plant in the smallest size from Forest Farm, one of the better permaculture-compatible nurseries on the West Coast. (We use them for a lot of our stuff, paying to have it shipped across the continent--the quality is excellent and the price is reasonable.) Expose the roots and scrape off a few nodules. Do the blender thing.
Inoculant and plant your Caragana seed and also keep your purchased plant going. I'd keep it in a pot for a few years until it was certain that you now had properly inoculated plants.
Lupin inoculant may be hard to find. As I recall, it was one of the species that requires its own specialized bacterium species. I'll hunt for our info if you can't find it but please try first. I'm older and don't have a lot of spare time left to do someone else's chores.
The most cosmopolitan nitrogen fixing bacterium is called the cowpea inoculant. Besides cowpeas, it works on lima beans, peanuts, yard long beans, etc. This is always supplied in the garden blend.
If you buy inoculant, you can keep it a few years by sealing the bag after use and refrigerating it. I inoculate legumes whenever I plant, regardless of whether I've grown them in that space before. It is not expensive and assures that you will get the most benefit from your crop.
Nobody commented on my remarks about using animals and rotating pig pens with gardens, etc. There was a reason for going off on that 'tangent'. This is a permaculture discussion group. We are concerned with design, not with looking purely at individual processes. We want to design soil building and/or maintaining systems that a) import mainly wasted products, b) export no more nutrient than imported, c) cycle nutrients in the design site so that the produces of one species are the resources of others, etc. That includes us. Urine is one of the easiest to use sources of nitrogen, everyone as access to it, and contains not only nitrogen but all minerals that our body no longer needs (except those lost in sweat, hair and nails, and, in women, menses.) Systems to efficiently return this nutrient package to the soil with little or no leaching should be part of our design. We have cycles at Barking Frogs Permaculture Center that efficiently move nutrients around between a tree crops area, for example, and our chinampa beds. This is especially important in our mineral deficient sands. Knowledge about nitrogen fixation and other sources is important, but we need to be looking at the design to achieve optimum and stabilize there. This is what is so beautiful about Fukuoka's system--it is integrated with a design, flowing season cycles and cropping cycles and nutrient cycles together. We haven't even touched on the pacing of nutrient availability, the pulses of release and rest that are best for plants. If you have a natural system to emulate, and you have a keen eye and subtle intuition, you can get by without all this knowledge and do very well, also. But the more you understand, the more you design instead of just taking the path of least resistance. (Nothing wrong with that path, but you might be able to design one with even less resistance!)
OK, now to your K and P question. Of course, I can't speak for the people who opined that they are harder to provide than N. I'd guess that since air is more than 70% N, that they figured it was at hand, fixable as we have discussed, so easier to get than minerals that come in stone or bone, and require serious energy to transport. That's just my guess. While most manures and also urine contain P (phosphorous), the proportion (with exceptions) is low compared to the N (nitrogen) content. However, with regular applications of manure, the P tends to build up as most soils hold it. Then the problem is to release it. In temperate climates, a green manure crop of buckwheat is very effective or a living mulch of white clover. When I experimented with jump starting a Fukuoka grain system on depleted soil, I started with a summer crop of buckwheat (in Massachusetts where it is cool enough for buckwheat in the summer) and of course seeded my white clover simultaneously. When we cut the buckwheat, the clover sprang up and covered the field. We broadcast winter rye into that. The following year, that rye made and excellent crop, indicating both adequate nitrogen and phosphorous (as seeds sequester phosphorous). The two accumulators made available enough P for a grain crop IN LESS THAN A YEAR. If the P is not present, of course, an accumulator has nothing to accumulate. More commonly, P is 'tied up' in fairly insoluble chemicals which root exudates from buckwheat and white clover can dissolve. Mycorhizzal fungi are particularly efficient at releasing and harvesting phosphorous and can make the difference between a good crop and a near total failure. Soil organic matter favors the fungi, and again there needs to be good matches between plant species and their root fungi species. Some mycorhizzae are relatively cosmopolitan and some are highly specific. Most plants require them for good health.
K (potassium) probably is available in most soils that have been glaciated. The glaciers transport and mix rocks and grind them and some, including for example granite, are sources of K. If you have chickens and no strong need of a calcium supplement, you can supply suitably sized granite particles (instead of oyster shell) for grit. The grit is eaten and goes to the gizzard where this powerful muscle grinds the stone particles against seeds to 'chew' them before they go to the stomach. Since birds keep needing more grit, we may assume that stones grind away after a while RELEASING LOTS OF MINERALS SUBJECT TO BEING MADE AVAILABLE THROUGH DIGESTIVE ACIDS. So this is one little design detail to bring K on site. If you are near the ocean, seaweed is a good source of K (and N and ALL trace minerals and a gel that helps hold water in soil for release to plants). Once or twice a season I have to spray BT and I always add seaweed extract to the spray as well as a bit of dishwashing detergent. The potassium ions in combination with the detergent are an adequate control of aphids all by themselves and help increase the effectiveness of the BT by weakening larvae that are coated and also sticking the spray to the leaves better. In the process, I am foliar feeding K to my plants. This is what Mollison means by stacking functions.
Wood ash is probably the commonest source of natural potassium, though you may consider it also a chemical fertilizer since it is so highly soluble with no organic molecules. Typically, wood ash contains about 10 percent K, a lot of Ca, and has half the pH elevating power of ground limestone. Its alkaline reaction is very rapid, so it should be used with discretion and many small applications are best. Wood ash is also an insecticide for soft bodied stages, a repellent of some insects and mollusks, and a quick way to get calcium to plants. We have been playing with container gardening here at BFPC. Once in a while we get a bit of blossom end rot on one of the tomatoes, typically growing in 35 gal. pots. This is a calcium deficiency that can be induced by drought. I put about a cup of wood ash in a 5 gal pot and fill with water. I put in as much as possible, up to the rim of the pot, and repeat until all the ash sludge has rinsed from the pail, sometimes needing to add water. This can take two or three days. The result is termination of blossom end rot, period, due to both the water supply (the wood ash acts as a surfactant, too, so the water penetrates all the soil in the pot), and so we get a darker green in the leaves, even the older ones, which I take to reflect the uptake of potassium.
In arid areas, pH of soil is likely to be high, and you probably don't want to use much wood ash. But arid soils are lightly leached and have a lot of mineral, possibly not needing any K anyway. And you probably shouldn't burn many trees in a region where they are scarce.
OK, we have a database with about 369 entries giving analyses for things like coffee grounds, maple leaves, cotton wastes, manures, etc. Things that have no significant value except to return to the soil. We've offered it for decades as a standard design but no one has ever bought it! You can find all the NPK sources you can handle there. It is also one of the standard designs we include on the CD that goes with our online course (but is available separately.) I don't even remember what we charge for it, but if someone is interested, I'll look it up. I have been pulling this together for 30+ years, mainly for my own use, and I personally use it a lot. You can do the same, of course, and save your money. :-)
Generally, in the United States we have so much waste that can be salvaged and used to build soil, that there should be no problem, certainly not in urban or suburban areas. I've always had an easy time gardening when I lived in one of these areas as there is so much wasted organic material of great value to the soil. Grass clippings (from untreated lawns) are a fantastic source of NPK and maybe trace minerals, depending on the soil and lawn management. Leaves are bagged in the fall in deciduous ecosystems and generally throughout the growing season(s) everywhere. With a chipper/shredder, small branches (i.e., from shearing a hedge) become ideal mulch. Harvesting this bounty gives you an opportunity to spread the word. People will ask why you are taking their 'trash.' You explain that it is too valuable to pass up, and that because you can get it free, you don't have to buy anything to fertilize your soil. Maybe you see an area that would be better managed with mulch without offending the landscape aesthetic of the home owner. (I don't believe in laying our trip on others.) You can mention this as you go right on piling the bags of good stuff in your trunk, pickup, or utility trailer. (Utility trailers are fantastic for having the benefits of a truck without the need for truck size and gas consumption.) When you lay down the mulch, various weeds and trees, etc., may germinate. I've gotten black walnut, butternut and pecan trees that way, for example, as well as apple rootstock from ornamental crabapple fruit in the rakings.) Out in the country, this sort of wealth is not available. We don't want people going into the woods and raking up leaves that are essential to that ecosystem to use for mulch! But most of us make trips to the city from time to time and we can learn when yard wastes are 'put out' and schedule accordingly. I do. I also hit every Starbucks I go by. Old coffee grounds analyses about equal to a slightly weak batch of cow manure, but doesn't stink. (I love the aroma of coffee!) Cow manure isn't that bad either, but tell that to most people. In the past, we have picked up surplus bread and kitchen waste from the local soup kitchen to feed to our animals. Whatever you scrounge for your critters ends up, in part, as manure for your soil. (Compost it first if you like work. For some people, this is a religious imperative.) If you bother to find out what the analysis of the material you scrounge might be, then your have the tools for balancing your soil. Some things, like deciduous leaves fallen from trees or wood chips are tricky as the analysis isn't the full story. But that's a place to start.
OK, I think I've shot my wad on this topic, which is probably more time on it than I devote to my paying students. :-) (They have a lot of topics to cover and so we move right along.)
Think systems, cycles, and ultimately design. The knowledge about particulars helps you shape the design. With good design, Fukuoka would never have experienced eventual lodging of his grain crop (after 15 or 20 years of accumulating N). We would have taken it off as a cash crop or cycled it to another part of the site that had need of N, for example, maybe his Mandarin oranges which are heavy feeders. How would we do that? Maybe feeding poultry in the orange grove with grain grown in the paddies that were getting nitrogen top heavy.
We haven't even touched the issue of balance between nitrogen, phosphorous, and potassium levels, the relationship between phosphorous levels and legume growth, etc. If this doesn't mean anything to you, you have some very interesting studying to do. Don't ask me where, though, as I picked it up as I went along, from all sorts of sources and of course observation.
Have fun!
For Mother Earth
Dan Hemenway
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In a message dated 6/13/08 3:52:48 PM, Mark.Fitzsimmons@pwr.utc.com writes:
Thanks Dan for the more detailed report on nitrogen fixing. You answered
my questions about specificity of n-fixing symbiotes, confirming what I
suspected and wrote about possibly needing to inoculate soil with the
proper organisms from naturally occurring know nitrogen fixers. I am
still left wondering:
are the nitrogen fixing symbiotes that associate with many common
legumes so prevalent that they are probably already in my garden soil,
or should I try to find cultures in nature somewhere, and where would I
find associates for things like peas? I have natural clover but find
peas don't do well in my garden. I always assumed it's because it's too
hot here in so. CA and plant them mostly as winter crops, but now not so
sure.
When I plant lupines or ceanothus, I will surely find some in the local
mountains and dig up a handful of soil by the roots to inoculate my
plants.
I am curious to know why Paul and Patrick a couple days ago said K and P
are more challenging.
Can you illuminate what your concerns are regarding these elements?
Mark
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