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| I know I should get a real soil test, but I didn't and wont until the fall.
This year I'm doing what I consider to be my first, real garden. I live on cape cod and my soil is sand. So back in the fall I started four 5' tall piles made up of kitchen scraps, leaves, horse manure/shaving and large amounts of coffee grounds and eel grass. I spread out the mostly finished compost in the garden (18'x18') about 3 weeks ago, and added 40lbs of dolomite (soil is acidic out here). I've been turning it with a shovel about once a week. Today I did a home soil test and it came up with a surplus of potash, a slightly low to nuetral ph, and I was deficient in nitrogen and phosphorus. I was expecting to be low in nitrogen and added 3lbs of blood meal right after I took the test and before I got the results. Any thoughts, recommendations, or advice? Thanks. |
Follow-Up Postings:
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| What any soil test says about Nitrogen depends on your soils temperature, so if the soil was cool enopugh that the Soil Food Web was not very active you would see a low level of Nitrogen, which may well be too much later on when the soil warms up. That is one of the reasons a good soil test lab does not test for Nitrogen today. |
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| That's very interesting. It's the first time I've heard it, but it makes total sense. Any idea at what temperature it becomes available? |
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| I'm not sure anyone really knows since I have seen mention of temperatures from the mid 40's on up with some people adamant that the soil needs to be in the 50's to 55 degrees. However my grass greens up long before soil temperatures get that high, indicating there is some Nitrogen available then. |
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- Posted by gardengal48 PNW zone 8 (My Page) on Fri, Apr 1, 11 at 12:39
| Soil temperature is only one factor (and btw, that is 45F/5C below which soil organisms are not active) and is only valid when discussing the mineralization of organic N. Nitrogen is present in the soil in various forms, both organic and nonorganic -- home test kits test only for available nitrogen, which tends to be the least stable form (nitrogen is the most mobile of the basic plant nutrients and is lost from the soil via volatilization, immobilization, denitrification and leaching). Many professional labs DO test for nitrogen (nitrate nitrogen - NO3) but this is only one of multiple forms nitrogen can take in the soil so is only an approximation of what existing levels of nitrogen may be. Because nitrogen is so mobile, it is most often deficient in soils, especially heavily cropped soils or those without benefit of applied organic matter. Virtually ALL professional soil tests will indicate a need for additional nitrogen, based on proposed crops. Organic matter is only one means of application - other methods may be more efficient and faster acting. |
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| Such as? Thanks everyone! |
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- Posted by gardengal48 PNW zone 8 (My Page) on Sun, Apr 3, 11 at 11:05
| Such as? High nitrogen fertilizers are the fastest and most efficient at delivering soluble, plant-available nitrogen - ammonium sulfate, ammonium nitrate, urea, etc. Nitrogen fixing cover crops are another good source but these, as well as organic fertilizer sources (seed meals, etc.) and manures/other OM, require mineralization to make the nitrogen available and that is dependant on soil biological activity and is not necessarily fast. Some organic sources - blood meal, bat guano - tend to be offer N in very close to soluble forms, so may be more efficient than other organic methods |
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- Posted by dianazone5 5 (My Page) on Sun, Apr 3, 11 at 13:47
| My 7th grader is working on this same thing as a science project for school. I have very similar results so far. 2/5 test sections are completed, with 6.5 pH, normal to surplus potash, and deficient in nitrogen and phosphorus. Makes sense that my plants were not very leafy and seemed to have pathetic root systems when I pulled them at the end of last season. It seemed like we had all the right things added going in to the season, but with the low production of tomatoes and non existent pepper production I was wondering what was wrong. The only thing that produced well were the bush beans. |
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