Save My Soil!

So I’ve been noticing my garden get a little tired over the past couple of years, and I can see my neighbor’s tomato and pepper plants, in particular, looking bigger and stronger. It also seemed to me that all kinds of plants were doing better for me in past years, like onions, cabbage, and garlic. So, time for some analysis. Is it possible that I’ve been losing soil fertility?

As you know, soil fertility is expressed as the amounts of the elements nitrogen, phosphorus, and potassium (NPK). Plus, the pH of the soil has to be right, and if it’s not then the availability of these elements to the plant is reduced. You can send your soil to be tested for fertility (see Our garden soil and And more on our garden soil for results from the Cornell soil lab), or you can do it yourself. So this time, for fun, I got a hold of the LaMotte Garden Kit to do it myself. Pretty easy to do.

I have to say, I was surprised, but not in a good way. But let’s start with the good news:

Plenty of phosphorus, just like in the Cornell results from a few years back. But look at this:

Ack! Somewhere between “Trace” and “Low”, which is dismal for a vegetable garden, where most of your plants are pretty demanding, with respect to N.

And here was the second surprise:

pH 8.0? Last time I checked we were at 7, i.e. neutral, and you want to be somewhere between 6 and 7 (a little acidity does not bother vegetables).

The potassium (K) test is not exactly colorimetric, it’s more like a titration, and you count the number of drops required to get to a certain color. The result there was Low, in K.

So how have I gotten myself into this situation? How come my neighbors seem to have more fertile soil than me, even when I routinely add organic fertilizers when I plant? Well, just not enough it seems. Unlike most of my neighbors, I start early, and stay late, so I’ve got a spring crop of lettuce filling my plot (plus arugula or radishes or cabbage or …), then I start lettuce (plus …) in mid-August, that grows until late October. Would you like to guess what vegetable takes the most out of your soil? That’s right, the leafy vegetables like lettuce have the biggest appetite for N.

Next up, in another post, we’ll talk about fertilizer and how I’ll try to fix all of this.

Brian O.