I have recently become interested in mycorrhiza, which is one of the soil web fungi. It effectively lengthens the reach of roots many times, enabling the plant to receive more nutrients and water than their roots alone could gather. Here is an introductory article. One of the benefits is how mycorrhizae can obtain phosphorus which is often present but unavailable because it's fixed with a metal. (Unavailable phosphorus does not show up on a soil test.) It makes the unavailable available. Other benefits are better drought resistance, better disease resistance, better soil aggregation. It would be wonderful to have lots of mycorrhizae. One of the things that inhibits them is soluble phosphate fertilizer. If there are lots of available nutrients, the mycorrhizae take a vacation. It seems that mild stress, the plant beginning to sense lack of nutrients or water, encourages growth of the mycorrhizae. Anyway, in relation to the discussion about what kind of fertilizer to use, keep the fungi in mind. Too much of any kind can impact them. Some general things about fertilizer: the organic kind works best when it's warm weather. In late fall the microbes are not active so synthetic would be better then. Synthetic can be used in place of organic but you do miss out on feeding the soil life if you use just synthetic. In light of what I'm finding out about mycorrhizae, I suggest aiming for minimum amounts (whether organic or synthetic), especially of phosphorus. Leaving your grass clippings on the lawn can reduce fertilizer use by 25%. If you have access to feed stores, using one of the grains, like Dchall suggests, is probably the most cost effective way to do organic feeding.

> Water is supposed to pour out of the bottom of the pot every time you water. It is necessary for gas exchange and the prevention of salt build up. Water is supposed to drip out of the bottom, not "pour". If you need water to "pour" out of the bottom for "gas exchange", you're not using a proper container mix. And if you don't overfertilize, you don't need to flush. >Besides, all the commercial growers I know try to conserve as much water as possible since it is their largest expense. In CA, sure. > They water very precisely but still need to water until water is coming well out the bottom of the pot. They can't monitor the water in every single pot. So I question what kind of precision they're applying. Large-scale precision isn't the same as seeing exactly how much water is going in/out of every single pot in your garden.

There's a website called "NPK of Everything Organic". It will surprise you what organic amendment is VERY HIGH in nitrogen. Since I'm not doing chemicals here, I'm going to have to wait 2 yrs for the dog hair to compost. That and feathers (which I have no access to). But, PetSmart and PetCo's grooming septs are now saving me their dog hair clippings. I'm adding it to the soil that I made only out of decomposed wood chip (because I could get that free and I needed quite a bit). So, now I'm adding dog hair to increase the nitrogen. Another good idea is to use Hairy Vetch as a cover crop. It fixes nitrogen as it roots. I know this isn't want you had asked, but I felt that the information was still helpful.

The only way tp know if NPK is lacking in your soils is to have a professional soil test done. And many testing labs will then tell you how and what to apply to bring things up to par. Nitrogen is the most heavily consumed nutrient but it is also the most difficult to measure. Many labs do not test for it at all. N is the most volatile and mobile of the basic plant nutrients and available N can change with time of day and weather conditions, as well as time of year. Mulching with compost or very well aged manure is one way to assure N will continue to be available without the willy-nilly application of fertilizers.