Archives for posts with tag: Copper

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.

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I finally found some time to look at the soil test reports and to compare them to each other and to last year (less to do in the garden means more time to spend doing other things).  The results were neither earth-shaking nor even startling but there were some changes, all of them for the better.

First—and most important—the soil pH for the east planter fell to 6.31, well within the optimal range (as recommended by Rutgers) of 6.20 to 6.80.  Last year, the pH was at 7.38, or slightly alkaline, and too high for most vegetable plants.  We added elemental Sulfur in the spring (see February 20, 2012) and it appears to have done the trick.

Similarly, the soil pH for the west planter was in the acceptable range—just barely—at 6.78.  The main difference between the soil in this planter versus the soil in the east is a lower proportion of compost.  Therefore, it would appear that the compost has a higher pH than the soil or peat moss.  By using less of it, we started with a lower pH than we did with the east planter last year.  For both planters, we will not need to make any adjustments (no Sulfur, no limestone) next spring.

Of lesser importance (and, perhaps, interest), the concentrations of macronutrients—Phosphorus, Potassium, Magnesium and Calcium—in the east planter have decreased, although all but one remains above optimum.  The exception is Potassium, whose concentration has dropped into the optimal range (whatever it is; the optimal ranges are not noted in the report).  The reduced Potassium concentration and the still-high Calcium concentration are consistent with the drop in pH and the recommendation not to add limestone (which is mainly Calcium Carbonate).

The macronutrient concentrations in the west planter are very close to those in the east with the exception again being Potassium.  Its concentration is higher and very near to what it was in the east planter last year.  That might explain why the west planter’s pH is higher.  The interactions between macronutrient concentrations and pH are very apparent from the testing results.

Finally, the concentrations of micronutrients—Zinc, Copper, Manganese, Boron and Iron—in both planters remain more or less the same.  They are for the most part classified as adequate (with no explanation of what that means) with Manganese and Iron falling into the high category.  These concentrations do not seem to have much impact and all are deemed not a limiting factor by the lab techs.

The bottom line is that as long as we maintain pH in the optimal range and continue to use balanced fertilizers, our soil will be just fine.