Archives for posts with tag: crop rotation

One vegetable dies, another takes its place.

One plant germinates, sprouts its tiny stems, spreads its leaves, grows larger, offers its colorful blossoms to eager pollinators, sets fruit, and then gradually, or sometimes quickly, puts forth a bounty of shiny produce to the gardener who tended it.

And then, more quickly, the plant fades away, its produce picked and its energy spent. No more pretty flowers or tasty vegetables. Most plants simply wither away at this point although biennials will contentedly continue to absorb and store energy for their flowering the second year (not having flowered or produced seed in the first).

Depending on the time of year and the climate, that leaves a vacancy in the garden, a void that would be wasted if left unfilled. If it is early enough in the summer and the first frost is not expected until late fall, there is plenty of time for a fast-growing vegetable—radishes are a good example—to repeat the cycle of life and death before winter descends.

That’s how succession gardening is supposed to work, anyway.

In the best planned garden, there is more to it than squeezing a second round of produce into the growing season. With careful selection of the first vegetable planted, when it is through the soil will be well prepared (even if depleted in some respects) for the plant that follows it. Likewise, the second vegetable, if chosen with thought, will leave the soil ready for what is sowed the next spring. This process can be stretched out over multiple seasons in what becomes long-term crop rotation (see May 18, 2014).

Theoretically, we follow this approach. In practice, we do the best we can. I’ve already described our crop rotation strategy (see May 4, 2014) and for succession planting, we do multiple sowings of root vegetables, including two or three early in the season and one late in the season, for which we are about due.

We also planted a mid-season replacement for the Sugar Snap peas, the last of which we harvested this morning. There were still plenty of peas but production had slowed and the leaves had begun to turn yellow. New growth had appeared at the base of several vines and I was tempted to wait to see whether it would bear fruit. But wanting to move on, we pulled them out.

In their place we sowed string beans. We planted the same varieties as last year—Amethyst Purple and Roma II—knowing that they are fast-growing and prolific (assuming the seeds are still viable, of course). I don’t know whether string beans are a good successor to peas in terms of soil conditioning but I do know that they are the only other vegetable we grow that needs trellising.

Also, I love to eat them.


Today, more digging.

Each time I pull out the shovel, I hope that it will be the last time. However, I must face this cold, hard fact: In the garden, there will always be digging to do.

For those who have not already stopped reading, I’ll skip the griping and keep it positive. We’re working on the planting area for the cucumbers which last year, we grew behind the west planter. This year, we’ll plant behind the east planter in what passes for crop rotation around here.

As noted in one of last season’s recaps (see January 15, 2014), our hypothesis for why the cucumbers underperformed is that we did not provide them with enough fertile soil in which to flourish (well, that’s one reason anyway). To test this theory, we’ll dig a continuous trench this time instead of the discrete pits we dug last year. This will result in more new soil available to each cucumber plant.

And it turns out that this also results in easier digging. Yes, we still encountered numerous rocks and boulders (I didn’t say that it was easy digging) but the elongated shape of the trench reduced the confinement of the rocks within its depth. Knocking them free with the shovel required half the effort needed for a small, circular pit.

Digging the trench also required half the time and we were done by noon. After a quick break for lunch, we filled the trench with soil; see May 11, 2014 for a description of that process.

To complete the setup, we installed stakes and chicken wire against the pool fence. I had expected the most difficult part of this task to be driving the stakes. However, as we learned last year, pre-drilling the holes with a steel rod and sledge hammer greatly reduced the necessary effort. No, the most difficult part was unrolling the chicken wire (which we purchased last year and which had been stored in the workshop since) and keeping it flat.

The area is now ready for the cucumber seedlings and we’ll set them out tomorrow. If they do better this year than last, we’ll plan on digging another trench behind the west planter next year. As I said, there will always be digging to do.

It turns out that when I was describing the benefits of crop rotation two weeks ago (see May 4, 2014), I was only half right. The process can be much more complicated—and substantially more advantageous—than merely planting different families of plants in different plots each season. The key is choosing what to plant and the order in which to plant it.

A good example of a more scientific approach to crop rotation is described in an Op-Ed piece by Dan Barber, chef of the restaurants Blue Hill (in New York City) and Blue Hill at Stone Barns (in Pocantico Hills, New York), that appears in today’s New York Times (see “What Farm-to-Table Got Wrong”).

Chef Barber buys his wheat from a farmer in upstate New York. On a visit to the farm, he learned that the wheat is only planted at the end of a four-year cycle of carefully selected crops, each of which performs a specific task for conditioning the soil. The procession follows a basic order which can be modified as soil response and weather patterns dictate.

First up is a cover crop such as mustard, which cleanses the soil and adds nutrients. Next is a legume to fix Nitrogen. Rye follows which, apparently, crowds out weeds (and also “builds soil structure”, although no explanation is given as to what exactly this means). Last to be planted is the wheat, the crop that outsiders (and until recently, Chef Barber) would think of as the whole point of this enterprise.

What is lamentable in the wheat farmer’s case is that the market for what those outsiders might call the off-season crops—the mustard, peas and rye—is scarce. While the wheat commands high, New York City prices, the other vegetables and grains go unwanted and often end up as feed for animals raised as food. Such use is not considered by most experts to be a very efficient use of resources.

Chef’s response to this situation was to develop menu items at his restaurants that incorporate the lesser crops and thereby elevate their stature and, presumably, their price (I hope that he pays his farmer as much for the mustard, peas and rye as he does for the wheat). It’s an elegant solution—a no-brainer, in retrospect—and also a win-win. Really, it’s a win-win-win because not only do the farmer and the chef benefit but the patrons of Blue Hill get tasty meals out of it, too.

So, how might this concept apply to the backyard gardener? Well, I’m not sure about growing an entire planter full of rye or mustard but half of a planter mixed with other like vegetables or grains might work (especially if Chef shares his recipes). And I never feel like we have enough Sugar Snap peas so the year of legumes would not be a problem. The primary issue is space, something we never seem to have enough of.

Maybe the question for me is, where can I put two more planters?

Last week, we dug the holes (see May 4, 2014). This week, we filled them.

Last year, I did a careful estimate of how much soil we would need and meticulously calculated the volume of the (assumed) conical mounds of soil on top. Of course, I was very precisely wrong and underestimated the total by a wide margin.

This year, I eyeballed it.

Well, okay, not completely (that would be contrary to my nature). At the garden center, I figured about four bags of compost per bale of peat moss (at equal proportions) of which I guessed we needed two. I then applied a factor of safety of 1.5 to the compost and got 12 bags.

Back in the garden, I wrestled a bale of peat moss (it is quite heavy and awkward) onto the wheelbarrow and Rachel sifted in a quantity about equal to a bag of compost. Bales of peat moss are very tightly compacted—they are almost rock solid—which made dispensing it even more difficult.

Peat moss is packaged in a bone-dry state, so we sprinkled it with water and gave it a stir. Like a magic trick, the water disappeared after only a few turns. We repeated the process with similar results until finally, after five applications of water, the peat moss looked slightly damp.

At this point, we added a bag of compost and stirred (with our hands) to incorporate. The moisture contained in the compost was sufficient to produce a workable consistency and we dumped the soil into the first hole. There was enough to fill it and to form a mound about six inches high and 18 to 24 inches in diameter.

Five bags and half a bale of peat moss later, we had filled and mounded the remaining holes. We were left with almost as much peat moss as we started with (counting the bale already on hand) so once again, my estimate was way off. I had not taken the peat moss’s compaction into account and as a result we purchased at least twice the necessary quantity. Also, my factor of safety on the compost was completely unnecessary.

It’s no matter; the peat moss and compost will not go to waste. We used some of it to top off and tidy up the mounds from last year which are now ready to be planted again. We can’t do any cucurbits (who inhabited these spaces last year) but perhaps we will try tomatoes (of which we have more than we can fit into the raised beds).

My second least favorite garden activity: Digging holes in our rocky, clayey soil. (Long-time readers of this blog know what my least favorite garden activity is; new readers can look at January 7, 2012 for a clue.) Unpleasant as it is, I have to face up to it if I want to be ready in time to plant summer squash and cucumbers over the Memorial Day weekend. More specifically, I need to start digging if I want to plant them in a different place from last year.

And I do want to plant them in a different place. Most gardening experts advise rotating crop locations every year. Moving vegetables in the same family around the garden helps protect them from insects and diseases that can hunker down in the winter and lie in wait for the new season’s plantings. Given our problems with cucumber beetles, aphids, bacterial wilt and powdery mildew, it is worth the effort.

Many sources advise a four-year rotation. Because crop rotation also helps balance demands on the soil (heavy feeders one year, light feeders the next), the suggested schedule sometimes includes a season of so-called green manure (peas, buckwheat, winter rye, alfalfa) to replenish nutrients or a cover crop to stifle weeds. I love the concept even if we cannot afford to lose any planter space to vegetables we do not plan to eat.

Any separation of the rotating groups is beneficial but to be maximally effective, there should be as much distance as possible between the individual planting areas. I’ve seen recommendations of up to a quarter-mile. That sounds good for large-scale growers but a quarter of a mile from my garden is practically in the next county. We’re very limited by the space available to us.

So we do the best we can. We have two raised planters and each year we alternate what goes into them. Last year, we planted cucumbers behind the west planter; this year, we will move the cukes to a similar location behind the east planter. And after laying out a dozen mounds for squash, we only dug and planted half of them last year, in a staggered arrangement. This time around, we’ll plant the other six. The separation is not huge but it’s not zero, either.

Which leads me back to the digging. It’s not my favorite activity but when it is done, the garden will be in a better state (and I shouldn’t have to do it again next year).

When I was growing up in the Central Valley of California, I often eschewed the agricultural aspects of life there. My hometown of Davis is relatively large (if not the largest) compared to other towns in Yolo County and, more significantly, is host to a campus of the University of California, for which both of my parents worked. Yes, UCD is an ag school—it was originally known as the Farm—but for us it represented the intellectual side of life and it was in this direction that I was aligned.

As I’ve gotten older, I’ve come to better appreciate the valley’s agricultural heritage. And since starting a backyard vegetable garden three years ago, my understanding of and appreciation for farming and the industry as a whole has been steadily increasing. So, while visiting my family this weekend (we were long overdue; see October 19, 2012; October 21, 2012; and October 24, 2012 for tales of our last trip), I decided to embrace my inner farm boy and take in a couple of the agrarian attractions that the valley has to offer.

Our first stop this morning—with my brother along—was the Heidrick Ag History Center in Woodland, the seat of Yolo County. Housed in two large warehouse buildings and connected by corridors at each end which create a central courtyard, the agricultural museum tells the story of farming in the valley through an expansive collection of farm equipment and associated lore.

The artifacts span more than a hundred years in age and include manual implements, horse- and mule-drawn plows and wagons as well as tractors and harvesters powered by steam or diesel engines. The steam-driven tractors are particularly impressive. One example has drive-wheels that are eight feet in diameter; its boiler is the size of a small shed and its chimney reaches almost to the ceiling. It must have been a wonder to behold when new.

The east building was chock-full of equipment, all impeccably restored and painted in bright colors. (The tractors would have been fun to climb on, had it been allowed.) The west building had previously housed a collection of antique trucks but its owners (who rented space from the History Center) recently moved it to another facility. Sadly (and inexplicably), I did not take any pictures.

Our second foray took us into the heart of the valley itself. The Yolo Bypass is a narrow but huge (hundreds of thousands of acres) strip of land running north-south between the cities of Davis and Sacramento. Parallel to the Sacramento River and surrounded by levees, the bypass acts as a detention pond for excess river flow that would otherwise flood the valley and its cities. After filling with water, the bypass slowly drains into the river downstream and thence into the delta.

Within the bypass is the Yolo Bypass Wildlife Area, almost 18,000 acres of protected wetlands which are home to a variety of aquatic and avian species. Wet is the operative word here because even during drought years (of which California is in its third straight), the bypass is periodically flooded, either to support the rice crops that are grown there or, in periodic fallow seasons, to support the wildlife.

In my memories of childhood, the bypass quickly filled and remained full—an inland sea, complete with waves and breakers—every winter. In more recent years (and, given the unreliability of my memory, probably most years), the water levels have been relatively low and the flooded areas distributed among the patchwork of rice fields that make up the bypass.

It rained all day yesterday (not great for visiting but a relief to everyone who lives here) and consequently, the ground was muddy and slippery. We could have parked the car and walked but, feeling lazy on a sunny Sunday morning, decided to drive the auto tour which winds its way along intermediate levees. It was dicey in spots and we could feel the car floating on a layer of muck. But had we chosen to walk, we would have sunk to our ankles, if not deeper.

It was calm and serene despite the fact that Interstate 80 crosses the north edge of the Wildlife Area on an elevated causeway. And lest we think that we were truly in the wilderness, the Sacramento skyline loomed to the east. Both the freeway and the city are good reminders of how California’s population is linked to the agriculture on which its success is largely based.

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.

At breakfast last Saturday morning (pancakes and eggs at our favorite local joint), we started in on early planning for this year’s garden.  The first thing we concluded is that we are not really early.  By some reckonings, we should have sowed seeds for thyme last month and could be starting other herbs right now.  The second thing we concluded is that, once again, we are behind schedule.

Luckily, the choices of what to plant this year were relatively easy decisions even though a fair amount of thought went into each one.  We started with the list of plants we grew last year and then applied a few different criteria to assess their success.

The most important criterion for each vegetable is our answer to the question, did we like it?  It doesn’t matter how well it grew or how much it produced if, at the end of the day, we won’t eat it.  Of last year’s crops—those that actually yielded fruit—the only one that did not absolutely thrill us was the Aunt Ruby’s German Green tomatoes.  They were not bad, per se, but they didn’t leave us wanting for more.  Consequently, we will not grow them again this year.

There was one plant whose fruit we could not taste.  The Delicata winter squash did set fruit—several of them—but was not able to develop any of them to maturity.  And that leads to the next criterion, performance.  Plants that did not thrive last year may not be suited to our particular microclimate.  Then again, we may not have given them what they needed, either.

So, what besides the Delicata did not perform?  Well, the Kabocha winter squash produced only one specimen by the end of the year and it was a small one at that.  That’s two strikes against the winter squashes and based on this meager showing, I was tempted to say that we should try other varieties this year or skip them altogether.

However, roasted with a little olive oil and salt, the Kabocha squash was absolutely delicious.  It passed the first criteria with flying colors even though it showed weakly on the second.  Similarly, although we were not able to sample the produce of our Delicata, it is one of my favorite varieties (we often buy it at the farmers’ market).  Therefore, we will try the Delicata and Kabocha squashes again.

The next criterion then is, why did these vegetables underperform?  My best guess is that we underfed them.  I haven’t reported on last year’s testing yet (look for a future posting) but soil properties are a definite suspect.  The areas we planted with the squash were newly formed last year and have not had much chance to stabilize.  This spring, we will probably need to enrich their soil and fertilize them more frequently.

The same could be true of the summer squashes—both the yellow crookneck and pale green zucchini—and the cucumbers—one a pickling variant and the other a slicing type—all of which we planted in more or less the same area (the ground surrounding the planters) and with roughly the same soil (equal parts of compost and peat moss).

Despite these similarities, however, their performance was quite different.  Three of the four summer squash vines were hugely productive (especially the alpha crookneck; see August 6, 2013) whereas the cucumbers produced only a modest quantity of fruit before fading away in mid-summer.  Two other factors could account for the differences.

First, the amount of soil we introduced for the cucumbers was much, much less than for the squashes.  This is partly because of their location between the pool fence and planters but mostly because the cucumbers were the last seedlings we planted.  By that time, we were tired!  Our native soil is rocky and very difficult to dig but we will have to face up to doing more of it this year.  Adding to and amending the soil will be an early spring chore.

Second, the cucumbers were stricken hard by powdery mildew and once afflicted, perished rapidly.  It is not clear (and probably never will be) whether this was due to their undernourished state or simply because the varieties we planted are more susceptible than others to powdery mildew.  The squashes, on the other hand, seem better able to continue to produce after contracting the disease.  Each of the squash vines was still setting fruit into the fall.

Both of these are factors we can mitigate—or try to mitigate, anyway—and so we will plant both types of summer squash and both types of cucumbers again.  To help control the powdery mildew (which is endemic in the northeast), we will plant in new locations.  I will also arm myself with a spray bottle full of baking soda solution which I will apply early and often.  With diligence—and luck—we will have more squash and cucumbers than we can eat this year.

The string beans weren’t the only plants that got pulled out this weekend.

The tomatoes, about which I have been obsessing lately, have not been improving despite my pruning of several days ago (see September 27, 2013).  Once infected with late blight (the suspected culprit), the plants have little hope of recovery without the use of fungicides.  Late blight is caused by oomycetes, non-photosynthetic fungi (perhaps that’s redundant?) that spread through the production of millions of oospores.  Oomycete is a cool word but it is a very uncool organism.

I have read about using a baking soda spray in several publications and websites (see, for instance, Late Bloomer’s Episode 2.16) and will probably try that next year, starting early in the season to prevent onset.  We’ll plant the tomatoes in the west planter—the best we can do, in terms of crop rotation—and keep everything as clean as possible.  However, given the ease with which the oospores spread and their ability to survive, underground, through severe weather, we are at a disadvantage (and greatly outnumbered).

It’s much too late for any kind of spray this year so I pulled out the spindly vines of the Sungold, Black Cherry, Brandywine (red and yellow) and Aunt Ruby’s German Green tomatoes that remained.  There were plenty of green (i.e., unripe) tomatoes but none that were fit to eat.  On all of the plants suffering from blight, the disease had spread to the fruit.  I don’t mind a rotten spot or two or even the occasional wormhole or bird peck, but the brown lesions, with their white spore sites, make even the best looking tomato unappetizing.

I’m happy to say that the plants were otherwise healthy and had produced extensive root systems (which required a fair amount of effort to pull out).  I was also pleased (and surprised) to see that the Country Taste Beefsteak tomato vines continue to resist the late blight; there were no signs of the lesions or brown spots on the leaves or stems.  This makes them a very good candidate for next year’s garden.

Of course, they are suffering from something else, possibly Septoria leaf spot (my hypothesis is based on review of photos of afflicted plants online) or maybe early blight.  Unfortunately, all of these conditions are spread by spores, the production of which is favored by the cool, humid weather that occurs in the fall.  I left the beefsteaks alone (well, I may have trimmed a few branches) in the hope that we will be able to harvest the dozen or so ripening tomatoes that are still on the vine.

Here’s another example of the benefits of second chances (see January 26, 2013).

A week ago (see June 20, 2013), we gave the Sugar Snap peas a reprieve from being ripped out.  Each of the vines had produced one or two new blossoms so we decided to wait and see whether they would actually produce another crop.

Well, seven days later, we not only have peas to harvest (including a few we missed from the first crop) but the vines are still blossoming.  Even as the original vines are fading from green to brown, they are producing new branches with bright green leaves and brilliant white flowers.  They are not getting much taller (with the exception of one vine which seems determined to climb up to the Giant’s castle) but they are getting fuller.

Further, most of the vines are sending out new branches from their roots.  At first it looked as if previously dormant seeds had germinated but on closer inspection, I found that the new growth is, in fact, originating from the existing vines just above soil level.  We did not observe this with last year’s crop (admittedly, a different variety altogether) which withered away once the peas were done.