Rhizo, True, the Study was on hydroponically grown tomatoes, but I would suggest growing in a 5:1:1 soiless mix in a SWC would have similar nutrition requirements. Correct? If one tries to use only one fertilizer (as in a buried strip in an EarthBox), it would appear in doing a mathematical average of the N-P-K numbers in the Paper, a combined number of 10-5-16 would be optimal for tomatoes. I am also assuming the soiless mix in an EarthBox with its wicking action would approximate nutrient needs in a hydroponic environment, or close to it. So, what commercially available fertilizer best matches an N-P-K of 10-5-16? This would be an interesting trial vs. Foliage-Pro or Tomato-tone..... Raybo

skizot, first of all, there is the law of limiting factors (see Liebig's law) which should determine whether a fertilizer is needed at all. Then there is the ratio of N,P and K in relation to each other. This ratio is the result of field trials and can be different for the same crop grown on different soil types. By far the most 'problematic' is nitrogen; the usual inorganic sources are very soluble and liable to leaching by rainfall or irrigation (inorganic urea will go from a solid product to a gas directly). To counter this, manufacturers are always seeking to extend the availability of nitrogen; this adds to the cost. I am more interested in the 'N sources' as stated on the fertilizer bag. If the bag proclaimes "16-4-8" and it states "Nitrogen source: 16% derived from urea", then that tells me that I can expect a quick green-up and an equally quick "green-down". If I get a strong shower of rain within a day or two, a great deal of the product will be dissolved and carried to places where it does not need to be at all, really. IBDU is a slow-release form of urea; it will cost more; the application rate will be the same as for untreated urea (lb. Nitrogen/1000sq.ft.) but it will give a more long lasting effect and will be better for the environment. I feel that the homeowner is misled on this issue. One manufacturer marketed the same "numbers" to commercial operators and homeowners. The difference was in the Nitrogen source. The all-soluble was much cheaper but would have to be put down more frequently to maintain the turf quality. Guess who this was marketed to.

I think too, we could chase the question in another direction. What if we asked and answered what's in the soda/juice/sweet tea that offers a potential benefit to the plant and is there anything in the leftovers that is potentially limiting?? In the juice & soda, we know there might be natural or artificial flavorings, neither of which are likely to be beneficial. There is water, which we know isn't a plus. We already know that some of the bio-compounds in tea are potentially limiting. So, we're left with the primary consideration, which is the sugar content. Let's clear the way by saying if the drinks are artificially sweetened, it's almost a certainty that it would have a limiting effect, or at best would offer no advantage to the plant. Even if it was needed and could be used by the plant, sugar couldn't be absorbed by the plant in molecular form. The hydrocarbon chain would need to be cleaved. Sugar (CnH2nOn [n is a number from 3-7]) hydrocarbon chains contain carbon, hydrogen, and oxygen, which are never deficient under normal circumstances, so nutritionally it looks like the leftovers are a bust. What does sugar actually DO when it becomes part of the soil solution? It increases the level of TDS (total dissolved solids and EC (electrical conductivity). What this does is make it more difficult for the plant to take up water and the nutrients dissolved in water. The goal of a good nutritional supplementation program should be to keep TDS/EC as low as possible w/o the level of nutrients being so low it causes nutrient deficiencies. From this, we can see that ANYTHING in the soil solution that is not nutritional is going to be limiting. To illustrate why non-nutrients in the soil solution are limiting, lets say that in a plant growing strongly, 800 ppm fertility is perfect when only the nutrients essential to growth are present in the soil solution, and they are there in the same ratio in which plants use them. Anything lower than 800 ppm carries the potential for deficiencies, and anything above 800 ppm makes it more difficult to absorb water & nutrients. Skewing the RATIO of nutrients in the soil solution even when the total ppm remains at 800 is also limiting. Adding sugar or any soluble substance the plant can't use has to be limiting. At 800 ppm with sugar being 100 ppm, there can be nutritional deficiencies even if the nutrient ratio is perfect. At 900 ppm with sugar being 100 ppm the effect is limiting because it makes it unnecessarily difficult for the plant to take up water - the primary cause of spoiled foliage in houseplants. I'm done. ;-) Al

Hi again everyone, thanks for all the feedback for my original question on NPK - Lisa, it seems that the bloom booster ratios vary considerably as we have a water soluble one here in Aust. which has a ratio of 15.8: 6.7: 25.3. Regarding the Seaweed product Kerry mentioned, as she said it is not marketed as a fertilizer but as a "tonic". It's a wonderful product which I have used as remedial treatment after severe hail damage where the hailstones were like small oranges and my exposed broms and vegetables looked like green confetti spread all around the garden. I have also used it after we had a heatwave on New Years Day a few years back where my exposed broms and vegies suffered severe heat damage as well as during a three day cold snap the following year where the exposed broms and vegies suffered severe cold damage. The plants bounced back much quicker than they had in the past from similar damage. However knowing what I do now, I should have used it as a preventitive treatment rather than a remedial one due to the following claims made by the manufacturer: Frost tolerance: It reduces frost damage, by lowering the temperature at which plant cells will freeze. This 'anti-freeze' effect reduces plant damage and hastens the return to productive growth once the temperature improves. Heat tolerance: It significantly increases a plant's heat tolerance and is taken up systemically, so it assists the whole plant. It can also aid in the return to productive growth following hot days. Drought tolerence: The same mechanism that protects against heat also provides significant protection against drought stress. It can even reverse the effects of dehydration after a single foliar application. Disease tolerance: It has been consistantly reported that plants treated with it demonstrate reduced incidence and severity of disease. Improved plant establishment: It contains naturally occurring plant hormones which stimulate root growth needed for rapid establishment of new plantings. It reduces the effect of transplant shock. (I get excellent results by giving my baby seedlings a soak in it before I plant them up and a good watering in with it after they have been planted. There are other benefits as well, just google the brand name to check them out and look at the fact sheet. I think there is also an international branch of the company so it could also be available for many of our brom friends on this forum. Thanks for the feedback once again, all the best, Nev