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Applying soybean meal / alfalfa meal to garden

13 years ago

We'll be planting our garden soon -- mostly tomatoes and beans. This will be the second year we have done lasagna gardening on our tomato beds -- our layers are mostly shredded leaves and hay. All beds will have compost also applied.

Our natural soil is very sandy and pretty low in nutrients, so we've been working on improving it, which is one reason we've done the lasagna gardening. It seems to have really helped last year.

My question is -- even though we are increasing the amount of organic matter, leaves and hay and compost are all pretty low in nitrogen. Tomatoes especially use nitrogen quickly. I'm thinking that to increase the amount of nitrogen available, a grain like soybean or alfalfa meal would be useful. I've seen the "normal" rate quoted at 10-20 lbs/1000 square feet (per year), but I think this figure usually comes from lawn discussions. Would it be a similar amount for vegetable gardens, and when would you apply it? All at once, when planting, or split it up and do, say, 5 lbs/1000 square feet several times throughout the summer? Or use a different amount?

Thanks for the advice.

Comments (6)

  • 13 years ago

    I'm applying alfalfa meal at the rate of approximately 55 pounds per 1000 sq ft - so, quite a bit heavier than the recommendation you cited. This is for a large garden planted to onions, garlic, potatoes, corn, and squash.

    The reason? A soil test last year (can't find the figures from the test) showed the nitrogen level to be quite low. And this is a garden that has been amended, with rock powders, horse manure, mulches, and a fall/over-winter crop of rye that gets tilled-in in late spring. But we've been taking food crops out of the patch every year, and it's had a history of being cropped since the mid 1950s.

    We had been spreading the rock powders (which offer little or no nitrogen) but concentrating the horse manure in the planted rows or hills. The patch needed an overall nitrogen boost. I don't plan to spread the alfalfa meal each year, but might do it every third year or something.

  • 13 years ago

    Why don't you just purchase a complete organic granular fertilizer & follow the application directions on the package? Because it's balanced you wouldn't get too much nitrogen which makes for large tomato plants, but few fruits. Beans don't need much nitrogen either, but actually can improve your soil for the tomatoes next year if you alternate the rows. Too much of any one thing with individual soil amendments could cause a problem for your garden and you might not have time to correct & replant before your summer crops planting window is over.

    Like joel_bc amending the row or planting holes for tomatoes, but not the entire garden is reasonable & cost effective.

    I've lasagna gardened for our new mixed perennial beds, but not in the vegetable beds. It's amazing how much it composts down from where you mounded it all up. I have used a lot of sheet mulch of various ingredients over the years with great conditioning.

    I've used alfalfa pellets as a topdressing around flowering shrubs & heavy feeding perennials, but not in the vegetable garden. I also have put them in a watering can to dissolve in the sun warmed water in summer, but it really smelled after a few days. Plus where I piled it up & didn't mix into the soil around the hostas it attracted a stray dog that broke all sorts of plant stems getting into the flower garden. I used the diluted liquid for recent transplants to get them off to a good start when planted in our summer dry season & was only a light green not a dark green color. I would be careful about mixing it into the root zone soil of young plants, but should be safe as a diluted tea mixture.

    Since I prefer to use soaker hoses for summer watering of vegetable beds, mixing a complete fertilizer into the soil prior to seeding or transplanting is less labor than side dressing or watering with anything additional than tap water.

    Find out what the organic gardeners in your area add to soils. You don't always have time or money for a good soil test, but they can give you a good idea of the condition of local soils whether usually acidic or alkaline.

    For example in my area with 60+ inches of rain 9 months of the year we have acidic soils that need yearly fall lime + nutrients even in manure enriched soils. It simply washes out, so I follow the recommended application rate in the spring and use organic mulches as well. Nothing seems overgrown or out of the ordinary, but grows more quickly now than in years when I only used poultry & rabbit manures from our backyard animals.

    It's worth the extra $ to buy the complete organic fertilizer for me. The brands in my area are Dr. Earth or Whitney Farms and the application rate is different for each, so I just read and follow the directions each time I use it.

    Hope that helps~
    Corrine

  • 13 years ago

    Soil Nitrogen availability is highly dependant on your soil temperature which influences bacterial activity, so if you test your soil for N when it is fairly cold and the bacteria are not very active the test will show little N available. I have found that if the soil contains adequate amounts of organic matter, 6 to 8 percent humus, there is ample amounts of Nitrogen even when a soil test shows a lack. If your plants are not growing well you might have a soil with low N levels, or it could be something else since plants, like us, need a balanced diet to grow well.
    Few soil test labs today test for soil Nitrogen for that reason as well as that many soils have too much Nitrogen and much of that excess is simply washed out of the soil and into our water which is why some water sources have enough nitrites to cause poisoning in young children. The soil test kits purchased from garden centers are not very reliable.

  • 13 years ago

    You should use your own urine. It's free, it's effective.

    You will not only save water, and decrease the strain on our environment through sewer/septic routes of disposal, but feed your garden in the process.

    I don't see the point of spending money on things like soybean or alfalfa (think about how many resources these things waste along the way in terms of inefficiencies regarding water, fertilizer, and transportation, too) when you can use your own urine.

    kimmsr's comments are interesting also.

  • 9 years ago

    fish podwer


  • 9 years ago

    Here's the difficulty in answering this question. You are composting leaves and straw, as well as growing vegetables at the same time.

    In order for your leaves and straw to compost, add the alfalfa. Gribbleton's suggestion of urine or LHarri57's fish powder will also work. Without the additional nitrogen, the fungus and bacteria will work slowly and in a year or two might finish breaking down into a usable compost for the plants. The additional nitrogen will accelerate the growth of the bacteria and get you to about 60% compost in a couple of months.

    For growing vegetables Oliveoyl3's idea of a complete organic fertilizer (COF) makes the most sense. Nitrogen helps things grow, but Potassium and Phosphorus are essential in developing roots, flowers, and fruit. COF's are designed to replace the nutrients that plants use when they are grown and then removed from the garden. They "top off the tank", so to speak.

    Here's the complication: you want to grow vegetables in a soil medium that begins with non-composted materials now that will change chemically over the season to stable compost by fall. Usually, you would be composting this material this year to use in a garden as compost next year when it is stable. You are growing vegetables in a compost pile. You will have bacteria and roots competing for nitrogen. Who gets it first? Will the plants suck up the available nitrogen and stop the composting process? Will the bacteria steal the nitrogen so the plants turn yellow? (This is what I usually see happen.) It is hard to gage. You have two dynamic processes going on at the same time. The ph of the soil will change over the season as well as the nutrient availability.

    I'm not saying it won't work. It's just a lot of variables going on at the same time. You will also need to analyze whether the advice you receive is addressing the needs of the compost or the vegetables and what unintended consequences are possible.

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