Our visiting professor weighs in on potatoes

According to the FAO (and their “year of the potato” campaign from 2008), 2008 was the year of the potato.  Did you all notice?  I may not have, except for the year-long display in the horticulture building at the University of Minnesota.  What I recently became curious about was how much garden space it would take for a person to grow enough potatoes to satisfy their annual average consumption.  But if you make it past that math in this blog entry, you’ll read about recent congressional action on the tasty tuber.  The government is not telling us how many rows of potatoes to plant in our backyard, but they’re discussing how many potatoes our kids can eat.

"La Ratte" fingerling potatoes

But first, how much space do you need for your annual potato need? OK, I’ll skip the math, but we need to assume what yield we can expect.  If we can get (on the low end) 100 pounds of potatoes per 100-foot row, we’d need a 35-foot row to get 35 pounds of potatoes.  And 35 pounds of potatoes is what the average American eats per year (not including pre-processed chips and fries and instant flakes, etc).  If we can get 150 pounds per 100-foot row, we’d only need a 24-foot row for 35 pounds of potatoes.  Imagine that this way: take 8 to 12 big-sized steps in a sunny spot in your yard.  Now imagine that area meeting or exceeding an average American’s (fresh) potato needs for the year.  Seem reasonable?  Why not try it next year?

But were this your typical blog, authored by enthusiasts or hobbyists, you’d be satisfied learning that much.  But no, this horticulture blog is rooted in science and current issues.  So by now, you’re pining for some research to sink your teeth into.  Some scientific debate or controversy, or even recent policy news, pertaining to potatoes.  So with that, I present to you: the Senate Agriculture Appropriations Bill for FY 2012.  This juicy piece of legislation (passed on Nov. 1) has a potato provision, a tuber maneuver, to bypass the USDA, which wanted to limit the amount of ‘starchy’ vegetables served in school lunches to 1 cup (2 servings) per week.  Their list of starchy vegetables also includes lima beans, peas, and sweet corn.  Two senators from potato-rich states (Colorado and Maine) put the amendment in, effectively blocking the power of the USDA to implement such a rule.  The reasoning given is that the rule would be a burden to school districts, which would have to find a way to meet nutritional guidelines with more ‘nutritional’ vegetables.   A conference committee merged the House version (with no amendment to limit the USDA’s power) with the Senate version on November 15, and the full legislation does indeed contain the Senate’s provision to protect potato producers.

Harvesting beets.  (Not sure why this is here.  Maybe because beets are better for you than potatoes?  Maybe just to see how darn cute Charlie’s son is?)

So what do you think?  Should kids not be allowed to eat more than a cup of lima beans, potatoes, corn, and peas in school each week?  Should it depend on how they’re prepared (French fries, for example)?  Can we grow enough broccoli to replace the potatoes that kids aren’t eating?  Would your kids eat kale and squash at school if peas and sweet corn were taken away?  Are you more like the average Russian, who eats about 286 pounds of fresh potatoes per year?  Discuss.

Podcast Season 2 is here!

My abject apologies for being late in posting this week.  I’ve been in Angel’s Camp, California since Tuesday – a lovely, wonderful place – but without anything above 2G wifi.  Needless to say, posting on the blog was impossible.  So I’m in the Sacramento airport, enjoying a glass of wine and a crab Louis before I leave for Seattle, and finally able to access a 4G connection!

In any case, here’s the beginning of Season 2’s podcasts.  I’m assured that soon we will be on i-Tunes, but for now you can download the podcasts here.  The first podcast is built around the theme of “Scary Garden.”  A little late for Halloween, but there you are.  For this first podcast, I take on lasagna mulching and bring you some garden tips for the fall/winter season.

Let me know if you’ve got some ideas for upcoming themes throughout November and December!

Looking for answers

“Stealing an idea from one source is plagiarism; stealing from many sources is research.”  This quote has been attributed to so many people I won’t bother trying to list them here.  But the point is a lot of what we do as professors is spend our time digging into the literature to look for substantiating or conflicting evidence for the ideas were interested in testing.  As a grad student back in the 1980’s, a time-honored tradition was to spend the afternoon at the library combing the stacks for journal articles, loading volume after volume onto a cart and then schlepping off the library copy center.  With the mechanical hum in the background and green glare of the scanner radiating off the walls, we’d wear our toner smudges like a badge of honor as the copy machine counte kept track of our progress.

Today, of course, things have changed dramatically.  The hardcopy CAB abstracts have been replaced by Google Scholar and Web of Science.  For those of us at major universities, hundreds of journals are available at our fingertips through on-line subscriptions through our libraries.  And an electronic interlibrary loan request can usually produce a .pdf of even the most obscure reference with a couple of days.  Unfortunately for those of us working in landscape horticulture some of the hardest to find journals were the ones that we often wanted most.  For example, journals from the American Society for Horticultural Science (ASHS) were only available to members and just recently became open access and indexed through Web of Science and other indexes.  Fortunately the situation is improving for two other sources that contain the type of applied research we are often after.  Arboriculture and Urban Forestry (formerly Journal of Arboriculture) and Journal of Environmental Horticulture are both available on-line (or partly available on-line).  More importantly for GP blog readers, neither requires a subscription or university log-in.  

Arboriculture and Urban Forestry is available at http://auf.isa-arbor.com/ 

Journal of Environmental Horticulture is available at http://www.hriresearch.org/index.cfm?page=Content&categoryID=174

Both journals include a search function to make it easier to find related articles.

Leaves for Lawn Fertilizer

Yesterday I happened to see a garden calendar encouraging people to pick up their leaves so that they don’t pollute streams and lakes by encouraging algae to grow.  This was a good idea, I thought, but then I started to wonder whether leaves on the lawn might not be a better idea?  After all, the reason that leaves cause algal growth in water is because of the nutrients they have.  And if they have nutrients couldn’t those be used for fertilizer instead of the regular fertilizers which we use?  What if we raked all of our leaves onto our yards?

There’s no denying that leaves which drop in the fall can make great compost, but how well would they work as a fertilizer? So I did a little bit of preliminary research — reading old papers and such — and here’s what I’ve come up with:

Fallen leaves are very variable in nutrient content.  Some leaves have 1% nitrogen, and some can have almost 3% (these are mostly from leguminous trees).  In terms of phosphorus, fallen leaves tend to have around 0.1%, though once again, it’s very variable.   For the purposes of this post I’m going to stick with nitrogen.

For 1,000 square feet of grass yard it takes about a pound of nitrogen per year to fertilize, even with a low input variety.

In a heavily wooded lot it wouldn’t be odd to have around 100 pounds of leaves fall in a 1,000 square foot area.  At 1% nitrogen, the leaves would provide enough nitrogen for the grass, but that would probably end up being a moot point because the leaves would have a good chance of smothering the grass. 

So what I’m wondering is, if we planted trees which were legumes, and had higher levels of nitrogen, and if we chopped up the leaves so they weren’t as likely to smother the grass (using a lawnmower or whatever) could we provide enough nitrogen per year for a healthy low input lawn?  Personally, I think so.  We would need to keep these leaves off of driveways and sidewalks because this is where they would do their worst in terms of contaminating water, but if they were just in yards — I think it might work.

Weird Plant Wednesday!

Inspired by Linda’s Euphorbia quiz last week – here’s another:

Euphorbia tirucalli ‘Firesticks’ in the Hahn Horticulture Garden at Virginia Tech (right before we dug it up due to impending frost). Am hoping for a "comment of approval" from Hap (Mister Cactus Jungle) on this nice specimen…not bad for Zone 6a!

Same funky little leaflets/antennae… just like Linda’s Euphorbia lactea ‘Cristata’

GP factoid: also known as "milkbush," the latex sap contains terpenoids – it apparently has potential as an energy source or "hydrocarbon plant."

Phosphate toxicity and iron deficiency

Bert’s post yesterday reminded me of some work one of my graduate students did about 10 years ago.  We were curious to see whether a transplant fertilizer containing phosphate was correlated with foliar iron deficiency, which is visualized as interveinal chlorosis:

 What Scott did was to plant 10 rhododendrons per treatment into pots containing containing a name brand azalea, camellia and rhododendron food (5-5-3) at 0, 0.5, 1.0, and 2.0 times the recommended amount. Here are some of the results of that study:

Total number of chlorotic plants

Total foliar iron vs. fertilizer treatment

Chlorosis as a result of phosphate fertilizer. 1= Normal (green leaves), 2= Light chlorosis in young leaves, 3= Moderate chlorosis, 4= Severe chlorosis, young leaves white

 For gardeners, the take home message might be that the control plants – those without any transplant fertilizer added – did the best. Don’t add phosphate to your landscape and garden soils unless you have a verified deficiency.  And only a soil test will tell you this conclusively.

You can’t fly by the seat of your pants on this one, folks.