Carol, the worm eats half decomposed OM. Then it binds inside its guts. Then it poops it out. Is it already ready for plant uptake? No. The degradation process continues with other organisms that are inside the pot, which they in their own stage need worm compost. Finally, the micro-organisms do the last job and the
water soluble nutrient is released: NO3K. Potassium nitrate. This salt that is dissolved in the water is the only compound that plants can really uptake with their feeder roots through osmosis. The salt is by then no longer an organic compound but merely a salt. The earthworms live on the early stages of the degradation process. Soil bacteria on the final. Worms will starve before your rosebush. Why would your rose eventually starve too?. If no new organic material is added, the existing salt is simply washed out or already uptaken and there's no more. Your plant will start showing yellow leaves because of the lack of nitrogen ( mainly potassium nitrate). There may be some leftover nitrate in the soil particles, but this is eventually either leached or uptaken until there's no more. The worm does its part. It keeps on eating if its food is available. It is an ongoing process. It doesn't happen in one go. Eventually if no more new decaying material is added it migrates or dies. Bacteria need the earthworm poop. If no more earthworm then the bacteria die...no nitrate in the soil, plant starts to starve for nitrogen ( main growth nutrient). All plants need the inorganic salt derived from an on-going organic degradation process. Soil scientists discovered this long time ago which allowed mankind to use non organic sources of potassium nitrate dissolved in water: the conventional chemical fertilizer. Why is it better to use organic matter over a chemical source?. Because OM is a slow releaser, instead of a highly soluble chemical potassium nitrate of which just a small fraction is used and the rest very fast washed down. My greatest concern about non organic that it is very wasteful and it sends out large ammounts of plant nutrients to the watersheds polluting them, creating conditions for algal blooms and disbalancing the ecosystem.
I do hope that this rather lengthy post helps to clarify you. Please keep asking until you got it!
Arturo
