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sherry_roma

Wonder if organics leave my Florida sand before decomposition.

16 years ago

My amended Florida sand is black and lovely, but it's still sand two years later. To rescue my mostly leafless Old Garden Roses this summer I've resorted to Miracle Gro in the last 3 weeks, and they have responded with new growth, blooms and larger leaves. I have concluded that I've been starving them with organic feedings that are not frequent enough to offset the leaching of nutrients in my sandy, high heat, high moisture garden. And now I'm wondering if the Rose-Tone, cottonseed meal, milorganite and alfalfa even stay in the soil long enough to decompose. Are they washing through the garden before they can become water soluble nutrients which I understand is 3 weeks?

Is there any research on this subject? Florida summer, Florida sand, Florida rain versus organics. My rose beds are heavily amended and mulched with horse manure compost, oak leaves and pine straw. Looking for your opinions. I'm not into ideology. I'm into well foliated rose bushes and healthy earthworm-filled soil in an environment of sand and heavy rain/heat. Whatever works while not killing my microbes and earthworms is what I will do.

Thanks in advance.

Sherry

Comments (10)

  • 16 years ago

    The good news is that synthetics, used reasonably, do not harm soil critters. Really the only way to harm soil critters with synthetic nutrient sources is to overapply significantly which results temporarily in salt levels in the soil going through the roof. This hurts plants too ;)

    Similar toxicity can result from ammonia in the soil when using uncomposted organic matter such as some manures. It's really a question of dosage, but when used in reasonable, moderate amounts the soil life will be just fine.

    Anyway, one problem you might be having with organic fertilizers is you may not be using enough. Most organic matter is very low in nutrients compared to synthetics. This means more needs to be used. For example you might find a bag of organic fertilizer labeled as 4-4-4, but it's pretty easy to find something like Miracle Grow as 20-20-20. In other words it's got 5 times the nutrient concentration as the organic 4-4-4 does.

    Also consider that water solubles like MG are recommended to be applied every couple weeks.

    Anyway, one recommendation I will pass along that I have heard about that makes sense to me (but I never tried as I don't have a sand soil) is to incorporate leaves into the soil. Probably not practical with roses already planted I know. It's not that the leaves add a lot of nutrients, it's that buried in the soil they tend to last a few years and help hold onto nutrients and water slowing the leech rate.

    Since you know the MG is doing the trick for your roses you kind of have to make a call. Would you rather use a synthetic that you know works and is cheap and easy or go through some more effort and expense and increase the amount and frequency of your organic material additions?

    Also keep in mind it doesn't have to be an all or nothing approach. You could continue adding modest amounts of organic matter each year to assist the soil in being as healthy as it can be and supplement with Miracle Grow (or a different synthetic) on an as needed basis. Perhaps you will find that over the years the frequency you need to use synthetics will decrease due to the regular additions of organic matter slowly building up a more plant hospitable soil environment.

    Please do not worry about the judicious use of synthetic nutrient sources adversely affecting soil critters though, it simply doesn't happen. Lack of organic matter as well as heavy use of fungicides/pesticides (including many organic ones) is what harms soil life.

  • 16 years ago

    justaguy2, thanks for posting so quickly. Everything you've said is encouraging. I found a Brevard County Extension (Florida central east coast) article that recommended organics for sandy soils and also said synthetics such as 6-6-6 and 10-10-10 were useful. I think I'll continue the compost in spring, milorganite and alfalfa throughout the year and use the MG more in the summer - maybe monthly in the cooler months. Fish emulsion is expensive as is Holly-Tone but I think I need it for all the minor elements.

    I have oak leaves as mulch in my backyard, and I intended to compost right on top of it in the spring. The same with the pine straw in the front. So maybe in 10 or 15 years the soil will be considerably better. But I'll be in a nursing home probably so it won't matter. :))

    As far as quantity of organics applied, sorry to say I don't go by the label. I did last year and suffered for it. This year I put down 4 cups of Rose/Holly-Tone in the 5x5 space around each bush along with that much alfalfa and milorganite. I never had any burn, and my bushes are always the best foliated in the spring. It was a good two months before I started seeing leaf loss, so that was probably the plants screaming that they were hungry. But I could not repeat that major fertilization again in July heat - or maybe not in cool weather either. I never realized that gardening was such a high effort activity.

    So I supposed my soil, climate and age force me to use a modified organic plan. OK by me - and the worms. I appreciate your taking the time with my question, justaguy2. You've been very helpful.

    Sherry

  • 16 years ago

    Since the nutrients in organic matter are not readily available they do not show up in the current test methods, but that does not mean they are not there. How well the organic amendments in your soil will perform depends on many things starting with what was your soil like before you started adding organic matter. If there was very little there then it will take some time, more than 2 years, for you to build up a good, healthy soil that will function like it should. No matter how much organic matter you add to your sand it will alwsy be sand, but it can be well amended sand and the organic matter will help mutrients stay in the soil and not move out into our drinking water.
    Since the soil I work with is sand, Lake Michigan beach sand, I have found the working organic matter in to the soil so stimulates the soil bacteria that they digest that OM so quickly that little is left to become the humus (residual organic matter in the soil) necessary to have a good healthy soil. However, putting the same amount of orgnaic matter on the soil, as a mulch, will over time increase the humus level in the soil quite well.
    If the synthetic fertilizer you use is very water soluble and if your garden does not have sufficient levels of organic matter in the soil to help hold those nutrients in the soil, they will simply flow out along with the water and be of little benefit to the plants. You need adequate amounts of organic matter in the soil to help hold nutrients where they are needed as well as to feed the plants growing there and if you have sufficient levels of organic matter you would find that a good, reliable soil test probably will show there are ample, and balanced, levels of nutrients in the soil meaning there is no need for any "fertilzier".

  • 16 years ago

    Thanks, kimmsr, by the reaction of my rose bushes they did not have enough nutrients before I used the MG. You are like me with your sandy soil, but I think the big difference is my high temps and frequent torrential rains. Maybe monthly feeding with the organics dry plant food would be enough to keep them happy, but I can't physically do that in the summer. Applying the MG took over 3 hours!! I fully expect to apply the 3 or 4 pick-up loads of horse manure compost in the spring - that is a given - along with alfalfa, etc. You should have seen my roses last summer. They were literally bare sticks. Being new to gardening, I was unsure whether they should be fed in the summer so I didn't. Well, that was a mistake. Believe me, I have done everything organically that I can physically do. I'm seeing that more is required for healthy roses in Florida. It's either this or pull them out and re-sod.

    Sherry

  • 16 years ago

    There are some gaps in logic in the previous post. Predominately sandy soils have minimal organic content to support the soil biology. If you don't have the critters (and there's a lot more than just bacteria involved), organic fertilizers are just going to sit there undigested and therefore unutilized. Increasing soil biology will not be an immediate process - repeated, consistent applications of organic matter (compost, composted manures, leaves, grass clippings, etc.) are necessary to build up the necessary populations. And this takes time, often years, to accomplish satisfactorily.

    Until you get to that stage, synthetic, water soluble ferts like MiracleGro may be the way to go. Roses as you know are heavy feeders - you will need to supply the necessary nutrients somehow. If you go the MG route, I wouldn't be overly concerned about nutrient leaching....in fact, a water soluble approach like MG is far less likely to contribute to nutrient leaching than a granular fertilizer application. You'd have to really pour it on to cause pollution issues and at 1Tbs per gallon of water applied every 3-4 weeks, that's simply not going to happen. I'd also make a tea out of the alfalfa to supplement as well. Apply both to the soil rather than the foliage - in your climate foliar applications are less efficient and could create phytotoxic reactions (foliar burning).

  • 16 years ago

    *** in fact, a water soluble approach like MG is far less likely to contribute to nutrient leaching than a granular fertilizer application.

    gardengal48, that's good information to have, and it confirms the experience of a rose friend. Everything in your post seems to fit with my thinking so I'm not sure about the gaps in logic. I do have lots of earthworms, and I use mychorrizae when I plan each rose so I'm pretty confident that there is life in the soil. My main question was could the Rose-Tone be gone before it even has a chance to work - in the summer. If it is gone, then it's a waste to put it out. Your statement above seems to indicate that may be the case.

    Sherry

  • 16 years ago

    Sherry, the gaps in logic were not contained in your original post but in the one immediately preceeding mine :-)

    And there may very well be (and probably is) life in the soil (darn hard to avoid) but very likely not in populations high enough or diverse enough to efficiently mobilize organic fertilizers......yet. Keep up with the applications of OM and you'll get there eventually.

  • 16 years ago

    Everything takes time.

    BTW, I had those phytotoxic reactions after the first application. Should have known better. Lost quite a few leaves on my E Veyrat Hermanos, but now he's got new growth sprouting everywhere. I rinsed well after the second application. :))

    Sherry

  • 16 years ago

    Florida 'sands' (I don't believe this so-called sand is mineral-based, but is from living creatures) have some big advantages, IME.

    Most areas are quite flat. The ph is not as low as many east-coast highly-drained soils are. It is a very fine sand and holds a fair amount of moisture much longer than one would think. In most areas there are zero stones, so hand or machine cultivation is incredibly easy. And as this thread indicates, it will give great results if some fertility can be gotten into it. Speaking of chemical fertilizer, don't forget about urine. Aged and diluted, it's an outstanding fast-acting fert.

  • 16 years ago

    All sand is mineral-based.

    The portion of sand that consists of long-dead sea creatures is CaCO3, a mineral. The other fraction in sand is from quartz, and quartz from weathering of landforms travels a long way to be deposited in areas far from origin. Any sand in FL and thereabouts is a fraction of quartz and calcium carbonate. AIUI closer to mountains in the N, more quartz. Closer to limestone and coral in the S, more CACO3.

    Nonetheless, in this thread, the OP should add OM to at least a double-digging depth to slow water movement and thus leaching. And keep adding. Raised beds are a good idea down there as well. Surely there is a FL gardening forum where people describe this.

    Dan