Finally! Our soil's finally been analyzed. We've been meaning to do this. All along we thought we had to send our soil to a university lab. That meant for us, gathering the sample, packaging it and mailing it too. No thanks; not interested! Then I asked our feed and soil-supplement guy Ed if he could do it. He's awesome (but that's another story). He did it all!
He gathered soil samples from 25 different locations in our garden. He gathered several pounds and carted it of to a local lab. We didn't have to lift a finger. Funny thing about this... he's been delivering organic feed and fertilizers to our door for more than 2 years now. If only we'd known he did this too!
The results are in!
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| Soil pH 6.8 |
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Before all this, we did a self-test kit from the local farm store. It seemed to be telling us that our pH was off the chart high. This new report by comparison is good news!
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| The vertical lines in the horizontal bars represent the desired level. We're well above the line on the big 3, phosphate, Potash and Magnesium. |
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| We don't know much about trace minerals; but we know they're important. Thankfully ours trace levels are high! |
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| Recommendation: 75 lbs of nitrogen. What? |
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All is well, save one thing... The report recommends 75 lbs of nitrogen on
1000 square foot per acre. Honestly, I don't even know what that means.
Your thoughts and insights into this report are welcome! Please share.
A bag of fertilizer has the NKP listed on it. This is in percentage of weight. Say you are using something with 5 as the N number. That has 5% nitrogen. Or 0.05 pounds of nitrogen/pound of fertilizer. If you want 75 pounds of nitrogen you need to divide by 0.05. That equals 1500 pounds of fertilizer.
ReplyDeleteNow before you freak out over this. Your report says 75 lbs per ACRE. Not per 1000 sqft. There are 44000 sqft to an acre. So 1500 lbs/acre divided by 44000 sqft/acre = 0.03 lbs/sqft. There are about 2.5 cups per lb in a typical fertilizer. 0.03 x 2.5 = 0.075 cups/sqft.
If you have a typical raised bed of 4'x8' That is 32 sqft. You multiply the two. 0.075 c/sqft x 32 sqft = 2.4 cups you put on a bed. Of course all these calculations say that have have a fertilizer with 5% nitrogen. If you have one with 10%, you would multiply by 5 and divide by 10. And get half the amount.
Or if you have real problems with math, you can just take the number 12 (don't worry how it was gotten) and divide it by the N number on the bag. If the N number is 7. Go 12/7 and you would have 1.7 cups per 4'x8' bed. Or tell me how big your beds are and what fertilizer you are using in an email and I'll let you know.
Oh! I was freaking out. Thanks for that small, per acre, detail. Our beds are 25x50, 4x20, 10x15 2x25, 5x10, 5x5,5x5 and 3x4.
DeleteFor the 25x50 bed I need 93.75 cups of 5% nitrogen fertilizer. Correct? Thanks so much. I could never have figured this out myself.
Yup you've got it. You might want to do that in pounds for a large bed. I do mine in cups since each bed is just 63 sqft. It is easier in cups. But 37 lbs for your big bed. Which is pretty much a forty pound bag of fertilizer.
DeleteGot it. Thanks.
DeleteSounds exciting. :) Good deal on the trace minerals! Somehow you lucked out on that. Pretty important stuff if you are basing a bit of your nutrition on what you are eating out of the garden. YAY
DeleteFunny thing about the trace minerals. I read your post about them a while back and ordered a bag and spread it. The soil sample was done before spreading the trace minerals. Now we have a double dose!
DeleteCouldn't be a bad thing. :) Those nutritional veggies will eat them up soon enough.
Delete"...Or tell me how big your beds are and what fertilizer you are using in an email and I'll let you know."
ReplyDeleteI'd take Daphne's advice on this. I don't know about you, but math makes my head hurt :)
Yes, I have already! Daphne is exceptional, a chemist by trade no doubt!
ReplyDeleteWow, what a great report. I just got mine back from Kinsey Ag and it recommends 850 lbs/acre (for an organic type protein meal)! The state recommended 0. Go figure. I'm working on a post comparing these two tests. Hope to get it up next week.
ReplyDeleteHow strange that you'd get two completely different recommendations from professionals. I look forward to reading your comparison post.
ReplyDeleteI am curious as to why the soil test makes a blanket recommendation for nitrogen. Put N on crops that don't need it or like it, you might get unexpected results. Ask Granny about her turnips (she got greens and no turnips). Beans make their own nitrogen, for instance. And tomatoes and peppers might not like all that nitrogen either. I always treat the crop I'm planting, and the area it's in - not the whole bed. Though in a small bed sometimes that's difficult to do. But for my large area (30x40) I never spread fertilizer over the entire bed.
ReplyDeleteThat's interesting Dave, because that's exactly how we've been doing it for the last couple of years now. I think the company we used is serving big farmers who grow one crop. either corn or soy. For us, we try to give our plants a shot of blood meal or fish and kelp emulsion when we plant them or when they are flowering. Sometimes we'll use it if they seem to be growing slowly. That's the case with our cauliflower right now, and the onions in the same row. Thanks for commenting. It's been helpful.
DeleteI keep meaning to analsyse our soil too but keep not getting around to it - I'm not sure if this has made me want to more or less, its not straightforward is it? Regardless though I hope it means you get better crops!
ReplyDeleteIt's not straightforward, but it's not to complicated either. The problem for me was that it's new. I always have a hard time doing something new. Once it's done I usually am glad I did it. That's been the case with this too.
ReplyDeleteThats wonderful that you have someone who will do it all for you. The numbers though are making my head spin.
ReplyDeleteThe numbers made my head spin at first too. Daphne was helpful. Dave's perspective is too.
DeleteThe nitrogen recommendation means that many pounds of actual nitrogen per 1000 square feet. These recommendations are usually geared towards using synthetic fertilizers. Here's a handy calculator page to book mark http://content.garden.org/gardenplace/calculators/index.php?q=form&type=nitrogen
ReplyDeleteYou could also just add plenty of manure and blood meal and watch how your plants grow. Are your greens dark green, or a little pale? If they are dark and grow well then you are probably ok. If they tend to be on the pale side then they need more nitrogen. Also be sure and inoculate your peas and beans so the bacteria on their roots can capture free nitrogen out of the air for your garden.
I fertilize my crops mostly individually too. At the beginning of the year mix fish emulsion into the soil all through the bed, then plant all the leafy winter crops. Then I follow those with the summer fruiting crops and add a little side dressed compost to them if they look scruffy. The leaf crops suck up most of the high nitrogen content at the beginning of the year, which keeps the fruit crops from getting to leafy and stemmy, and let's them make more and better fruits. I really should do more experiments with this stuff and see what kind of difference the fertilizer actually makes.
ReplyDelete