Archives for posts with tag: acidity

It would be hard to tell from this blog (because I have posted so few real-time entries since mid-fall, 2014) but I decided not to send any soil out for testing this year (well, technically speaking, last year).

During the previous three seasons (2011, 2012, and 2013), I collected soil samples in late September or October (see October 19, 2013, part 2 for the most recent account) and sent them off to the Rutgers Soil Testing Laboratory. Two weeks after that, the lab sent me via e-mail me a report of our soil’s properties (see February 14, 2014 for discussion of the October, 2013 results).

It was a worthwhile endeavor—information is power, and all that—and we made some adjustments that I am sure were of benefit to the vegetables. Probably the most significant factor that the tests brought to our attention was soil pH. Initially, it was too high and the following year (2012), we added Sulfur to bring it down.

But after that first year, we did not learn anything new. Our soil’s pH has stabilized within the optimal range and both the macro- and micronutrient levels have remained constant. The soil appears to have reached a healthy equilibrium and as a result, there have been no recommendations for change. And as they say, if it ain’t broke, don’t fix it.

This year, the vegetable plants themselves are telling me everything I need to know. Almost all are very happy so the soil must be okay.

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More snow yesterday—a lot more snow—means that it is still too early to be thinking about starting any work on the garden outside.  At this rate of snowstorms, we won’t be digging out until March.

That is just as well because there are still a few items from last year to recap.  Most notably, there are the results of the soil testing that arrived at the end of October (2013) but which I have not had a chance to discuss.

Based on the previous year’s testing, I was not expecting any startling new information for the east and west planters (see October 19, 2013, part 2).  Sure enough, the reports confirmed my expectations.  The all-important pH of the soil remains within the sweet spot (6.20 to 6.80) for vegetable gardens with the east planter at 6.57 and the west planter a tad more acidic at 6.23.

Interestingly, the soil pH of the east planter increased slightly (from 6.31 in 2012) while the soil pH of the west planter decreased (it was 6.78 in 2012).  The soil in the east planter is now squarely within the preferred range but the soil in the west planter is bouncing from endpoint to endpoint.  Both are perfectly fine, however, and we will not have to make pH adjustment to either.

Similarly, the macro- (Ca, K, Mg and P) and micronutrient (B, Cu, Fe, Mn and Zn) concentrations in the east and west planters are close to each other, a result, I think, of at least three factors.  First, we treat the planters identically; neither has received any amendments (other than a top dressing of compost at the beginning of the season) or more fertilizer than the other.

Second, we have been rotating crops back and forth between the planters.  Therefore, their soils have been depleted (or replenished) by more or less the same amount.  Third, the age of the soil in each planter is more than two years.  I assume that given their consistent treatment, both soils are converging on the same steady state.

For the most part, the micronutrient levels in the west planter decreased when compared to last year (i.e., 2012).  This is not too surprising, again considering that we don’t heavily fertilize or otherwise modify our soil during the growing season (I think of it as time smoothing the soil’s rough edges).  Micronutrient levels in the east planter are mostly the same as 2012 (its soil is older and smoother).

What I didn’t expect is that in both planters, the concentration of Calcium increased by almost 50 percent.  We did not add lime, bone meal or any other source of the micronutrient so I have no idea from where the additional Calcium comes.

So much for the well-established planters.  On to the ground level soil, where we planted squash and cucumbers last season.

For starters, the pH of this soil is too high at 7.10 (the soil is slightly alkaline).  We’ve learned from both of the growing seasons prior to last that this can have a very detrimental effect on plant performance.  And I learned from this year’s experiments with seed starting mix that the culprit is probably not the very acidic peat moss, of which the ground level soil is roughly half.  The other half is compost (mainly cow manure) which tends to be more alkaline.

When we dig new pits for the squash and cucumbers this year, we will have to increase the proportion of peat moss to manure and perhaps add some elemental Sulfur to bring the pH down.  Otherwise, the ground soil profile resembles that of the planters.  The macro- and micronutrient concentrations are very close, including—somewhat mysteriously—the high concentration of Calcium.

This is a bit ironic because the summer squash plants experienced a high rate of blossom end rot last season, a condition that is usually associated with Calcium deficiency.  I think this is what the testing lab was alluding to when they called me in the fall (see October 24, 2013).  The testing methods based on acid extraction indicate a high concentration of Calcium but it is not, apparently, in a form that plants can readily use.  I’ll have to look into this one further.

The reports list lots of numbers, not all of them obviously meaningful.  So, what does it all mean?  The bottom line is that our planters’ soil is doing fine and that with minor modification the soil in the ground will come into line as well.  That’s good—if not exciting—news.

Yesterday, we made a run up to the Adams Fairacre Farms store near us.  They have a well-stocked garden center, open all year, and we went there to procure seed starting mix.  We also found an amazing selection of seeds, including those of the Hudson Valley Seed Library about which I wrote last year (see January 5, 2013).  Good to know in case we decide to buy more seeds this year.

They had at least three brands of seed starting mix on offer, all different from the brand we used last year.  The ingredient lists looked similar and included a combination (in proportions not disclosed) of peat moss, vermiculite and/or perlite.  Some also contained compost or other fertilizers (most notably, the Miracle-Gro product which boasts both Miracle-Gro Plant Food and MicroMax nutrients).  These are superfluous for seed starting; the seed itself contains everything the plant needs from germination until leaf growth.

After browsing the available mixes and looking over the extensive array of soil components and amendments also for sale, I decided to make my own seed starting mix this year.  I recalled from my previous research that all that is really needed is peat moss, for structure, and vermiculite, for water retention.  I have more than a bale of peat moss left over from last year and picked up a bag of vermiculite to add to it.

Today, I decided to do a bit more research to determine what the best ratio of materials might be.  I didn’t find any definitive answers—as with most topics, there are a lot of opinions out there—but I did perceive two common threads.  First, many gardeners recommend adding perlite to keep the mixture lightweight and to facilitate drainage.  Second, several others suggest including a small amount of lime to balance the low pH (high acidity) of peat moss.

I made another trip to Adams (luckily, it is not far away) to buy the perlite and lime.  A definite advantage of the do-it-yourself approach is that all of the mix components are cheap.  For less than $20, I will have enough mix for this year’s seedlings, including potting up.  The lime will last substantially longer (in fact, I will probably never have to buy it again).

When combining the components, I will initially mix two parts peat moss to one part each of vermiculite and perlite. One recipe called for a quarter teaspoon of lime per gallon of mix, which seems low but is as good a starting point as any.  After that, I will adjust as needed to produce a consistency that seems right.

This is a case where my intuition will have to guide me.

After returning home from running errands this afternoon, I was surprised to find a voicemail message from the soil testing laboratory.  This is the third year I’ve sent them soil for analysis and I did nothing different this year compared to the previous two years.  What could the issue be?

I gave the lab a call back and learned that they were concerned that the tests I requested might not be appropriate for our soil.  Based on a brief visual assessment of the soil samples and their labels (“East Planter”, “West Planter”, “Ground Level”), and without checking the type of planting for which the soils would be used (as I had indicated on the back of the soil test questionnaire), the lab scientist thought that perhaps I worked for a mall and was checking the soil from its indoor flower beds.  I’m not sure whether to be flattered (or not).

It turns out that the basic soil tests I commissioned are intended for mineral-based soils and use acids to extract the nutrients of interest.   This method is efficient and quick and yields reliable results for total nutrient content.  However, for soils that have very high concentrations of nutrients in mineral form, the observed values may not represent how much of the nutrients are actually available to plants.  For example, a clod of partially decomposed ore may be rich in iron but spinach still won’t grow well in it.

Alternatively, for compost and other soils rich in organic matter, extraction by water solubility is usually employed.  Apparently, this method takes longer and is somehow more complicated (I infer, because it costs much more) but produces values that are closer to what is readily available to a plant’s roots.  I explained our soil’s situation—it is used for a vegetable garden—its composition—it is a mix of compost, peat moss and native soil—and its history—she looked up the previous years’ reports—and weighing this information, she decided the basic tests would be okay.

The soil scientist said that many people are (and here she groped for a politically appropriate word) enthusiastic about adding organic matter to their soil, by which I believe she meant to imply that they add too much.  Looking at our previous reports, however, she saw that although some of our nutrient levels are high (“above optimum” is the lab’s term), the values are not off the charts.  I think she concluded that the total and available concentrations of nutrients in our soil should not be too different.

Looking more closely at our previous analysis results, she liked that our soil pH was in the green zone (6.20 to 6.80) last year and noticed that in our first year (the east planter only, in 2011), our pH was high.  I reported that based on the report, we adjusted the pH by adding elemental Sulfur and that was probably why we were at the proper acidity by the end of the 2012 season.  She was happy to hear that someone actually followed their recommendations.

The lab will start the soil testing tomorrow and I hope to hear back from them next week.

While we were visiting a friend in his home (lucky us, he had invited us for one of his fantastic brunches), he asked about the purple string beans:  Do they, he wondered, taste any different from the green ones?

It is a good question.  Purple is an unusual color in the vegetable garden, second only to blue in rarity (is there any blue comestible other than blueberries?).  And while color is not always an indicator of flavor—the taste of red and green apples is not that different, for instance—it can be, especially when the color difference is due to ripeness, or lack thereof.

The answer to our friend’s question, though, is:  No; the purple string beans taste more or less the same as do the green ones.  In fact, as the beans cook, the purple fades away, leaving only the familiar green tint.  This is because heat and loss of acidity (due to dilution in neutral water) break down the anthocyanins that produce the color purple.  Chlorophyll, the green pigment (and component of photosynthesis), is apparently more stable.  (If we grow the purple string beans again next year—which is likely—I might try cooking a batch in vinegar or lemon juice to see whether that preserves the purple color.)

That matter resolved, I’ll ask my own follow-up questions:  What about the other vegetables growing in our garden?  Does their color dictate the flavor?

Well, as an indicator of ripeness, sure.  An unripe green tomato has a vastly different taste compared to a ripe red one.  We don’t grow them here, but apples (and most other fruits) exhibit this property.  It should be noted, however, that not all vegetables change color as they ripen.  Eggplant, for instance, starts purple and stays purple throughout its growth (and even its blossoms are tinged with purple).

But what about different colors of ripe tomato?  Do the yellow and orange varieties have a different flavor from the traditional red ones?  How about tomatoes that are green when ripe?  Furthermore, are the differences in flavor, if any, due to the color or is the color just an indicator of the difference?

Answering the last question first, I think the color is merely an indicator of a difference in flavor and not the cause of it.  The various colors of tomato do have varying flavors but the variations are due to different levels of sugar and acidity.  And as noted above, pigments react very differently to acidity.  Typical red tomatoes are relatively high in acidity so acid-resistant pigments like carotenoids (of which lycopene is the most common in tomatoes) will dominate their color.

At the other end of the spectrum (in both flavor and color), orange, yellow, green and purple (sometimes referred to as black) tomatoes are sweeter in flavor, a result of their being lower in acid.  Another consequence of higher pH is that pigments less resistant to acid, such as the anthocyanins, can survive in their colored state and contribute to the tomatoes their distinctive hues.  In other words, the pigments act as a natural litmus test to visually signify flavor.

This is only a quasi-scientific analysis but it makes sense, at least for the tomatoes.  In addition to the tomatoes, we also planted different colors of carrots, radishes, beets and bell peppers this year.  To my taste buds, the red and white-striped Chioggia beets tasted the same as the Touchstone Gold and neither tasted any different from the typical all-red variety.

Similarly, there was only one significant difference between the taste of our Quadrato d’Asti Rosso (red) and Orange Sun (guess) bell peppers and the common green variety.  The peppers we grew tasted less grassy, a flavor component that I can only call “green”.  This is a good thing because that grassiness usually puts me off bell peppers.

Our radish crop was not sufficiently successful to make an assessment of their flavors but the carrots, which flourished a wide rainbow of colors, also yielded an array of flavors.  The orange were the most typical (no surprise there) while the yellow and white were woodier and the purple were sweeter.  The range in flavor was not quite as great as in color or as stark as with the tomatoes but there was definitely a correlation.