Hello Paul and all >They've discovered our secret!
:-) It's about time they discovered a few of their own secrets I think. One is that it's quite hard to find phosphorus-deficient soils. What's easy to find is lots and lots of soils where there's plenty of phosphorus, but it's all locked up in a form not available to plants. So the chemical-agriculture solution is to apply loads of water-soluble phosphates (superphosphate or triple-superphosphate), a tiny percentage of which ever gets to the plant, the rest goes into the soil water or joins the existing stocks of unavailable phosphorus. The phosphorus supply in the soil is either in mineral form (as above) or in organic forms in the organic matter and humus in the soil, where it's taken up by soil microorganisms in their tissues and becomes available when they die (ie slow-release), while some species of soil microorganisms produce available forms of phosphorus in excess, more than they need, like honey bees produce excess honey. Mycorrhizal soil fungi are a major source of organic phosphorus, fed direct to the plant roots. But if you keep knifing harsh chemical fertilisers into the soil the organic matter supply gets burnt up and the soil goes acidic, with not much living in it to supply phosphorus or anything else much, and certainly no mycorrhizal soil fungi. If you maintain the soil humus and the biodiversity of your crops you get it both ways, via the soil life and via the plants themselves, with deep-rooters etching fresh minerals out of the subsoil, including "unavailable" phosphorus, which they do by exuding weak carbonic acid from the roots. There's possibly a case for applying phosphorus once, at the beginning, when restoring worn-out soil. Organic farmers previously used basic sludge for that; I don't know if it's still available or still suitable. A good dressing of manure, or green manure, or indeed urine, but preferably compost, which contains them all plus all the soil bugs needed, is usually sufficient. Other than that, phosphorus deficiencies are for amateurs. IMHO. Like nitrogen deficiencies. Best Keith >Urine Offers Rich Phosphorus Source >http://dsc.discovery.com/news/2007/07/10/urine_pla.html?category=earth > > >July 10, 2007 รณ Recycling urine may be the answer to a looming global >shortage of phosphorus, according to an Australian researcher. > >Associate Professor Cynthia Mitchell, of the Institute for Sustainable >Futures at the University of Technology, Sydney (UTS), said the >world's deposits of phosphorus are due to run out in about 50 years. > >She believes recycling the 132 gallons (500 liters) of urine each >person produces a year is the solution. > >"Urine is the most concentrated source of phosphorus," she said. "At >the moment we dilute that through our sewage system and send it out to >the ocean. > >"In the industrialized world we must start moving to a >resource-recovery approach rather than the current waste-treatment >approach." > >Phosphorus is a key component in agricultural fertilizers and a lack >of phosphorus would affect future soil quality and production. > >But Mitchell blames a 'poo taboo' for the failure of governments to >move on the issue of recycling urine. > >In a public lecture at UTS later this week, Mitchell will call for a >"revolution in sanitation" across Australia. > >She said technology that allows urine to be separated in the home is >already being used in Sweden. > >All new homes in the local council of Tanum are required to have >urine-separation toilets. > >-- >Thanks, >PC > >He's the kind of a guy who lights up a room just by flicking a switch _______________________________________________ Biofuel mailing list Biofuel@sustainablelists.org http://sustainablelists.org/mailman/listinfo/biofuel_sustainablelists.org Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Search the combined Biofuel and Biofuels-biz list archives (50,000 messages): http://www.mail-archive.com/biofuel@sustainablelists.org/
