Saturday, April 6, 2013

Using a Soil Testing Kit

In 2006, I built raised garden beds and filled them with a truckload of fresh soil from an organic supplier in Seattle.  Each year since then, I've added generous helpings of compost from my own compost bins.  In other words, I knew my soil was good from the start, so I never saw the need to test my soil for pH, nitrogen, and the like. 

However, last summer I noticed a real slow down in my garden's productivity.  All my vegetables struggled, especially tomatoes and beans.  At the time, I chalked it up to the fact that (a) we experienced one of the coldest Junes on record, and (b) I discovered symphylans, aka evil lifeform nodes, festering in the soil.  (More later on the symphylans.)

While the cold temps and evil lifeform nodes contributed to last years' disappointing crop,  now I'm thinking that declining soil fertility might be an accomplice.  I recently came across this article that says compost does not contribute the necessary N, P and K to maintain proper soil fertility to grow vegetables.

My compost bin system digests primarily yard waste - grass and leaves and clippings - with some food scraps mixed in.  I don't add anything else to the compost, like bone or blood meal, kelp, etc.  Which means that if my grass and yard clippings are all lacking in certain nutrients, the compost will be deficient too.  The fact is, I have no clue whether my soil has sufficient fertility or not.  Why not find out? 

I bought this $7 kit from the garden nursery with little test tubes and colored pills.

Green = pH
Purple = Nitrogen
Blue = Phosphorus
Red = Potash

Timing - I administered the test on March 9, two weeks after I had applied compost to the raised bed where I tested the soil.  

According to this test, my pH, phosphorus, and potash are fine, but I'm low on nitrogen.  The tube with the purple cap is the nitrogen tester.  How accurate is the test?  There's an interesting discussion of that question here:

Even if the tests aren't 100% accurate, I'm not all that surprised that my nitrogen is low.  In fact, I'm kind of glad!  Low nitrogen is a much easier problem to fix than climate change (abnormally cold June) or symphylans (evil lifeform nodes that not even Monsanto can figure out how to kill).  
Now I need to explore some options for increasing nitrogen that don't involve little blue crystals .  .  .

No comments:

Post a Comment