Soil pH and nutrients: amending your soil organically
Andrea Bellamy |

NPK test results.jpg

Ever wonder what these funky little kits are for?

Before planting in the spring, I like to do a quick soil test for pH (soil acidity or alkalinity) and nutrients (your basic NPK, or, nitrogen, phosphorous and potash [potassium]). I just use an inexpensive testing kit from a local nursery, although if you want a more detailed soil analysis or suspect you have serious problems with your soil, you can have it tested in a lab. In the US, your cooperative extension office does this. In Canada, try this.

I don’t really need a kit to tell me what’s up with my soil; Vancouver soil is typically acidic and nutrient deficient (perhaps because the rain leaches the good stuff out?). Despite regular amendments with compost, I’m always fighting those underlying traits. I like to do the test anyway, partially because it’s fun in a nerdy Grade 8 Science kind of way, and partially because I just want to double check.

This year’s test didn’t reveal any big surprises. Again, my soil was borderline acidic, so I’ll add a bit more lime. If your soil is alkaline, try granular sulphur, coffee grounds, or pine needles.

As for the nutrient test, my soil was low in phosphorous, and even lower in nitrogen. Typically, other than amending with compost and manure, bone meal and blood meal are suggested as organic soil supplements for these deficiencies (blood meal is high in nitrogen; bone meal in phosphorous). I’ve used both in the past, but this time I decided to look for alternatives to these slaughterhouse byproducts. No, I’m not a vegetarian, nor am I concerned about contracting BSE through the use of bonemeal. But in the past year I’ve stopped buying commercially-raised beef, so it would just seem wrong to use a byproduct from that industry. And I also question how blood and bone meal can be considered an organic amendment, when they aren’t likely produced from organically-raised beef. Plus, well, let’s face it: spray-dried blood is just icky.

Thankfully, there are vegetarian alternatives to blood meal, bone meal and fish fertilizers:

Instead of blood meal or fish emulsion, try alfalfa meal* or alfalfa pellets (sold as rabbit food) to raise your nitrogen levels. With an NPK ratio (the percentage of available nitrogen (N), phosphorous (P), and potash (K)) of about 3-1-2, alfalfa is a green manure that also provides a dose of phosphorus and potash. Because it heats up in the soil, (making it a great compost accelerator) be careful not to burn your plants: don’t add it to the planting hole.

Cottonseed meal*, with a NPK ratio of approximately 7-2-2, is another good nitrogen source. Available at your local feed store, cottonseed is acidic, so unless you’re trying to lower your soil’s pH, avoid it or use in combination with lime.

Soft-rock phosphate, with a NPK ratio of 0-3-0, will raise your phosphorous levels and is a good slow-release substitute for bone meal.

*In the interest of full-disclosure, it seems unlikely that these products would be sourced organically-grown plants, unless otherwise noted. Is that why the organic gardening guidelines developed by Garden Organic (following standards set by the British Organic movement, the UK
government, and the EU) don’t endorse the application of any fertilizer, organic or otherwise?



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