Software
Houzz Logo Print
m_gold

Advice: adding Nitrogen to my vegetable garden

10 years ago

I have a raised bed vegetable garden. In the fall I piled leaves (not mulched), layered 3-6", on top of my raised bed. Earlier this year i used the lawnmower to shred the brittle leaves into dust or small bits, then I tilled it and my soil before planting seeds this year.


When tilling the soil I noticed many many warms which made me thing I did a good using the leaves to keep the soil slightly insulated over that winter. But recently I read that leaves can actually reduce the available Nitrogen in the soil.


Is this a problem I should worry about? If so, should I buy or use some product to counter thus mistake? Last year the garden flourished without any fertilizer, thanks to people on this site helping me to use the right mixture and make the soil quite rich for all the plants.

Comments (17)

  • 10 years ago

    Don't worry about it so much if it's flourishing according to your needs. You can get a soil test but it sounds like there is a fair bit of organic material and worms are also a good sign. IMHO, you can probably continue exactly as you are doing with mulch, but maybe not worry about tilling it - with that many active worms, they will do a lot of the work in moving things around, and if stuff is growing there, that will also have an impact.

  • 10 years ago

    Leaves and straw are a clear example of a brown becoming a green. It starts with earthworms eating one, producing castings which are bacteria food. Bacteria then fix nitrogen to further digest the castings. More slowly available than fertilizer or even decomposed legumes, but there is nothing wrong with that.

  • 10 years ago
    last modified: 10 years ago

    Layering leaves will attract worms as you have seen. Tilling will make the worms wish they went somewhere else to eat. I have adopted the no till method for several years now and just let the worms till the soil.

    IF you frame off an area (a bed) to grow in and no longer walk on it and cover and/or mulch the soil get and stays surprisingly loose.

    IF it turns out you need N a sprinkling of blood meal should help easily.

  • 10 years ago
    last modified: 10 years ago

    Tilling any high Carbon material into the soil can result in a temporary tie up of available Nitrogen as the Soil Food Web uses that N to digest the Carbonaceous material. The presence of earthworms indicates there is adequate amounts of organic matter for them to eat but has little to do with Nitrogen in the soil.

    All browns contain some Nitrogen, but they do not become a Nitrogen source. The Carbon to Nitrogen (C:N) ratio of straw is about 75:1 or 7r parts Carbon to 1 part Nitrogen while the C:N ratio of leaves can vary (depending on age) for 40 to 80 to 1.

    Browns (high Carbon material) do not become greens (high Nitrogen material) even if an alchemist waves a magic wand over them.

    kimmq is kimsr

  • 10 years ago

    bacteria 1, alchemists 0. ball to the center.

  • 10 years ago

    Another reason not to till.

  • 10 years ago
    last modified: 10 years ago

    While I used to dig every bed I've planted using hand tools (pick axe and digging fork), I'm getting older and now use a tiller to create new beds. I always cover my beds through the winter with a thick layer of mulch (leaves, straw, etc...) Last year I started to garden this property for the first time. It's a fairly heavy clay, with a clay base underneath that you could form pots and dishes from lol. It was mulched all last growing season, and covered with the mulch all winter (mostly whole leaves.) The plants were harvested and there was no fall turning done.

    I got the tiller, created 3 new beds this year and mulched them immediately. Instead of using the tiller on the old beds, I raked back the mulch, took a digging fork and turned the soil. The worms were everywhere!

    Now keep in mind, we're talking about clay that just makes you cry lol. When moist, you can shape it in your hands, and when dry it varies from concrete to brittle mortar. The mulch left all year succeeded in allowing the worms to keep that soil tilled and aerated. As I turned with the fork, using a 1 - 1/2 dig method (stick the fork in to the base of the tines, lift the load out a little, and re-step on the fork before turning. The winter's mulch/leaves/old grass clippings were incorporated as I went. The soil, and I kid you not, after turning rose to a foot and half above it's original height. Not from additions, from the worms de-compacting the clay.

    I'll probably do this for at least another 2 years. If it keeps expanding, I may even need to remove some soil from each bed. After 2 - 3 years I'll hopefully switch to a completely no-till method.

    I do use some (extremely small amounts) synthetic fertilizer (I got a bunch of bags given to me from someone, and there's no sense in seeing go to waste.) And I add urine during the off-season.

    Yes, N gets temporarily tied up, but as the soil biology decomposes the organic matter, and the worms eat and leave castings, the N is now ever-available to the plants as the decomposition is a reasonably long-term process.

    Keep on what you're doing, switch to a fork on the established beds (use the tiller on new beds if you wish) and depending on what you started with, before long you'll have some great stuff there.

  • 10 years ago

    I use a digging fork as well on my clay. Less likely to chop worms in half and it doesn't chop up the spongy structure as much. The tiller is good initially to get some stuff incorporated, but as that microscopic (and visible as well) spongy structure develops, you want to preserve it and not pulverize everything and start over every year. So, less disturbance as time goes on is the best approach.

  • 10 years ago

    I use a spading fork, to reduce weeds before planting in spring. I take out those that are already green, and do break ground some to follow and extract grass rhizomes. I think it is less damage to the soil to weed after winter, as live roots stay in the ground when it really matters.

  • 10 years ago

    Once you get adequate amounts of organc matter in the soil and an active Soil Food Web turning the soil becomes something that is not needed since the Soil Food Web will do that for you. Tilling upsets the life of the members of the Soil Food Web and destroys much of the fungi that develop over time.

    kimmq is kimmsr

  • 10 years ago

    All the stories I have heard about people reviving problematic soil (esp clay) have involved lots of extra organic matter and mulching. Some swear by tilling/turning, some swear by doing nothing, some a combination. But the commonality is that they _all_ involve lots of mulch and organic matter.

    This makes me think it's mostly about the mulch/compost, and the tilling/turning only a marginal factor.

  • 10 years ago

    it has to do also on developing deep roots. You need the infiltration down and up (capillarity). A lawn soil, with its generally short roots, is more difficult to remediate than a soil where you have planting options.

  • 10 years ago

    Along with glib's point, turning also allows deeper cultivation. For relatively shallow soils like mine, with a base of pure clay, drainage can be a real problem. Establishing a deep, organic-matter-incorporated cultivation, through turning, vastly improves the long-term viability of garden beds. Once that's established though, the soil biology maintains it fairly well through continued and appropriate additions of OM and the use of mulch.

  • 10 years ago

    if you for some reason can not plant deep rooted plants, hugelkultur is the next best option. Deep roots really avoid cultivating, otherwise you have to break the soil. You have to have the deep OM. Scattering compost on top is seldom a complete solution.

  • 10 years ago

    Worms eat leaves. You might consider saving shredded leaves and periodically re-applying them to the soil as a way of feeding worms and keeping them healthy. Don't bother to till shredded leaves into the soil. Tilling in leaves won't help the worms and it will disrupt the soil-food web.

    It is my opinion that much of what is said about 'browns' depleting the soil of Nitrogen is a mistaken observation. Yes, applying un-decomposed or partially decomposed material, like wood chips, to soil will cause plants to suffer. But, in my opinion, it's not because of a lack of Nitrogen. I believe the lack of growth is a symptom of the ongoing decomposition of organic matter. Adding Nitrogen has never been observed to help the situation.

    Fun!

  • 10 years ago
    last modified: 10 years ago

    "Adding Nitrogen has never been observed to help the situation."

    Can you supply documentation for this statement? The use of nitrogen by bacteria can indeed temporarily 'tie-up' the prevalence of available N. If available N is added to a soil, sure bacteria may increase (and thus put the N to use,) but there will also be some taken up by plants. The key factors seem to be levels of 'available' N, the types of bacteria present, and their food sources. The types of bacteria are directly proportional to the types of organic matter. So, if a high carbon ingredient exists, so too will the bacteria which prefers that food source. As long as those bacteria have the resources that they need to multiply, including N, they will be active. Increase the N, and if there are plants growing, the plants will use what is available to them in whatever amount they can find and need, but too will the bacteria continually convert organic forms of N, to inorganic.

    So, if I understand the processes correctly, as long as there is available N in the presence of plant roots, air and water, plants can make use of that N. Tie it up, and even if temporarily, it won't be as present in available form, nor free to be taken up by roots. Bacteria will compete for the N if their high carbon food stocks are present.

    Basically, using composting as the medium, add 'greens' (high N sources) to the process and watch the bacteria go to work. Reduce the number of greens, or increase the browns (lower N sources,) and watch bacteria multiplication and activity slow down. Edit: I should add that using compost to make the point should also include the idea of balanced ratios. Even in soil the bacteria, and all life, will eventually reach a 'critical mass' (there's a better term) for the conditions present.