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Balanced Fertilizer and Peak Phosphorus

When I first started reading extension recommendations for plants around 15 years ago now, I read a lot about “balanced fertilizers”.  Today I still see balanced fertilizers recommended, but not nearly as frequently, which is a good thing.

At this point you may be asking yourself “what is a balanced fertilizer?”  A balanced fertilizer is one that has three numbers on its label which are the same — such as a 10-10-10 or a 14-14-14 (Nitrogen, Phosphorus and Potassium are the three nutrients indicated by
these numbers).  Although it might seem like equal numbers would mean equal amounts of these nutrients, these numbers actually indicate percent Nitrogen, percent P expressed as P2O5 (in other words, if you took all of the phosphorus present in the fertilizer, made it into P2O5 and then added it back to the fertilizer and figured out what percent of the fertilizer that made up — that would be the second number) and percent potassium expressed as K2O (basically the same as the phosphorus example you saw previously).

But here’s the problem.  The amount of phosphorus, and often potassium, that is added when you use a balanced fertilizer is typically out of line with the amount that the plant needs.  This is because fertilizers are usually applied based on the amount of nitrogen that a plant needs.  The reason that a balanced fertilizer was usually recommended was that phosphorus and potassium levels in these fertilizers is high enough that they provide all of those elements that a plant needed without being toxic to the plant.  The problem is that, while the levels of these nutrients added might not be toxic, they are in excess of what is usually needed.

OK, so we’re adding excess phosphorus and potassium, what’s the problem?  Well, for the potassium the problem isn’t usually that big a deal.  In fact, a fertilizer bag with the first and third numbers equal may be what’s called for in many cases — fruits and nuts in particular often like a higher level of potassium.  Additionally, the world has a pretty big store of potassium so we’re not likely to run out any time soon.  Phosphorus, on the other hand, is a little bit different.

Phosphorus is a bit more hard to find in large quantity than either of the other elements in a bag of fertilizer.  Because of this it is often the element that limits the growth of plants, for example algae.  When phosphorus runs off into a lake or other body of water it can allow algae to go crazy and use up all of the oxygen in the water killing fish and other creatures (actually it’s the dead algae that do this — bacteria use oxygen while breaking the algae down).  Most of you are familiar with this and know that it’s the reason why Minnesota and now Wisconsin have banned the use of phosphorus fertilizers on lawns without a soil test.

But here’s what you may not know.  Most of the phosphorus which we use for fertilizers comes from rock phosphate.  Rock phosphate is mined in only a few places around the world, Florida being one.  Just as it is a foregone conclusion that we will run out of oil someday, it is also a foregone, but lesser known, conclusion that we will run out of rock phosphate.  Estimates are that we will reach “Peak Phosphorus” (in other words maximum phosphorus production.) in 20 years or so and that we will run out in 50 – 100 years.  Here’s an interesting article on the situation  http://www.foreignpolicy.com/articles/2010/04/20/peak_phosphorus

So conserve our natural resources and skip the balanced fertilizer.  When asked for a general use fertilizer recommendation I usually recommend something with a ratio of roughly 5-1-2, with a higher potassium content if you’re growing fruits or nuts.

Restoration ecologists – you need us! Part 2.

Last month Linda posted on the need for horticultural knowledge for those trying to restore native habitats or at least establish native plants. There seems to be a pervasive notion that if we plant natives all we have to do is stick them in the ground and walk away. They’re native, right?  Don’t need irrigation; don’t need fertilizer; all that good jazz.   Well, often there is lot more to it than that.

 


A case in point.  Over the past couple of years I’ve been watching an unintended experiment near the State Capitol grounds in Olympia, WA.   The State opened up a vista so that the south end of Puget Sound and the Olympic Mountains were visible from the Capitol campus. It’s a lovely view.   As part of the development, a switchback trail was established on the steep hillside to connect the Capitol grounds with the park surrounding Capitol Lake below. A great idea.  Along the trial the hillside was planted with an array of native plants such as Oregon grape, salal, alder, and western redcedar.  Another fine idea.  Now comes the problem.  Near as I can tell, there was no plan for maintaining these native plants.  In fairly short order the hillside has become overrun with grasses, dandelions, and Himalayan blackberries – not exactly the desired effect.  And therein lies the rub.  Everyone is on board to plant natives but who’s on board for the hard work to maintain them.  Keeping weedy species from this planting by hand would take an army volunteers.  Burning is likely out due to the proximity of the Capitol and probably wouldn’t promote the desired species.  The answer?  Most likely a combination of hand-weeding and herbicides.  It is interesting that when the end justifies the means, herbicide is not such a dirty word anymore.  So there you go.   In order to effectively establish and maintain native plants, not only do we need to know about Mahonia aquifolium, Gaultheria shallon, and Alnus rubra; but it also helps to know about glyphosate, flumioxazin, and triclopyr.

The importance of knowing your plants

One of the first courses a horticulture student takes is plant materials, or, in the case of a forestry student, dendrology.  Why?  Pretty simple; it’s hard to select plants if you don’t know what they are and what they’ll do in the landscape. Of course, the classic example is a large tree or shrub planted in a tight spot that eventually devours an entire house.  But we usually don’t have to look too far to find situations where a homeowner or landscaper clearly had no idea what plant he or she was dealing with.  To wit, a couple of recent examples of poor plant choices (maybe this can be our next series after “Why do nurseries still grow THAT?”)

I spotted the first example wandering through downtown in my hometown of Olympia, WA.  At first glace it looks like an ordinary hedge; boxy to by sure, but nothing remarkable.

As I passed by though I noticed the hedge was actually a weeping Norway spruce (Picea abies ‘pendula’ – actually it could have been an ‘inversa’ – the repeated butchering made it hard to tell).  Either way, what could have otherwise been a fairly interesting plant had been reduced to a squared-off blob of blech.  The other side, of course, is that if a squared off blob of blech is truly desired there are cheaper and easier ways to achieve the effect.

The other example of the perils of not knowing your plant material comes from northern Michigan.   This case represents that other extreme of trees that grow too large for their space.  Here the homeowner wanted to screen his house (on the left but out of camera range to protect the guilty!) from the railroad track on the right of the photo.  Solution: Plant some conifers! Sounds like a good idea to me.

Only problem – the owner chose to plant the screen with dwarf Alberta spruces!  As with the blob of blech, the property owner could have achieved the desired screen in a couple of years and at a small fraction of the cost with seedlings from their local conservation district or seedling nursery.  In any event, we’ll check back in about 40 years and see how it’s working out for them…

 

Jicama (The Yam Bean)

Every once in awhile I get the urge to try and find something interesting in old literature, and today was one of those days.  So I went over to my pile of old “Journal of Economic Entomology” journals and snatched a 1943 issue from the top.  The pest issues that we had to deal with during the war years were interesting because resources were tight — we had DDT (and lead arsenate), but all of it was going to the front to protect our soldiers from lice.  So scientists back home were trying new things.  One which I had never heard of before today was getting a serious look: The yam bean.  The yam bean is a tropical legume which has a great deal of potential as a high nutrient food crop (the root of the bean is what is edible, not the seeds).  The food part is interesting to me, but more interesting is the fact that a dust could be made from grinding the beans into a powder which would kill insects.  After looking through some articles I discovered that the primary source of toxicity in the yam bean is rotenone and some similar chemicals.  I’m not a big fan of rotenone, still, this plant is fascinating.  An edible root and seeds which can be used very effectively as an insecticide.  Why wasn’t this plant more common 50 or 100 years ago?  What other plants are we missing out there which are useful?

Want an organic source of nitrogen that isn’t shipped from halfway across the world? Urine luck

There are lots of organic fertilizers out there:  Fish emulsions, corn gluten meal, guano.  Many of these fertilizers (all that I listed above with the exception of the guano) are by-products of some other industry.  Still, they need to be shipped from somewhere to somewhere to get to our garden and so they cost energy — and of course they cost us money.  But there is a high nitrogen fertilizer that you can use which doesn’t come from a long way away, and that’s pee.  Holly  mentioned using pee to help compost piles of stray a few months ago (you can find the news story on the right side of this blog), and I, for one, think it’s a great idea.  But really, pee can be used as a fertilizer without the compost.

Yesterday I was working on a project and decided to goof off a little by figuring out how much nitrogen was actually in urine.  Here’s the conclusion — Urine contains about 4,000 pats per million nitrogen.  In terms of what plants can handle, that’s a lot (which is why dogs produce “dog spots” when they pee on a small area of ground — too much nitrogen in a small area).  400 parts per million nitrogen, applied once a week in irrigation water, is what you might apply to encourage the growth of greenhouse plants.  Urine, by the way, is also relatively sterile (unless you’re dealing with a bladder infection) and so using urine is relatively safe as long as it’s used quickly.  It also conserves water because you don’t need to flush.  So, the way I figure it, you could mix 1 part urine with 9 parts water and have a really good once a week (or two weeks) fertilizer application for your flowers (I don’t know if I could bring myself to fertilize cabbage, broccoli, or tomatoes with it…).  You’d be saving yourself the cost of fertilizer, saving the environmental cost of shipping the fertilizer you might otherwise purchase, saving water, and you’d have something unique to tell your gardening friends about.  Win – win situation as far as I’m concerned.

Questions on sustainability

Linda’s recent post on the sustainability of topiaries got me to thinking, is any horticultural practice sustainable?  And, does it matter?

 

Picking up on the topiary theme I thought of the ultimate form of tree manipulation, bonsai.  I few years ago I visited the National Arboretum in Washington DC, which includes an incredible bonsai display.  Some of the bonsai specimens in the collection originated in Japan and are over 300 years old.  Is 300 years long enough to consider this a sustainable practice?  Does it matter as long as there are individuals willing to devote the time and effort to tend and prune these awesome and inspiring plants?

 

More recently I visited the International Rose Garden at Washington Park in Portland.  Established over 90 years ago the garden is one of the premier attractions in Washington Park and in Portland.  Maintaining the garden, however, requires paid staff and an army of volunteers.  Is 90 years long enough to consider this sustainable?  Does it matter as long as the city is willing to commit resources and volunteers are willing to line up to dead-head and pull weeds?

 


Closer to home, I maintain about an acre of my place in lawn and various beds – trees, shrubs, herbaceous perennials and even a few (gasp) annuals.  Is this sustainable?  Does it matter as along as my family and I enjoy our surroundings and are willing to commit the time and effort to mow, weed, edge, prune and dead-head?

Garden seminar coming to a place near you?

I just got back from British Columbia where I spoke to 2 garden club/Master Gardener groups.  It’s always easy for me to do seminars in BC or along the west coast, but I rarely get a chance to go elsewhere.  Many times it’s the expense that keeps groups, especially garden clubs and nonprofits, from bringing in speakers.

So here’s my idea:  I keep a gift account budget here at WSU with the donations people make towards my educational program.  Occasionaly I’ll make an equipment purchase, but for the most part it’s intact.  And today it hit me – why not use it to help fund travel throughout the US (or elsewhere?) to give educational seminars? 

So before I go any further with this thought, maybe some of you can give me feedback.  Would your institution/garden club/or other group be interested in having me give a seminar on some aspect of sustainable urban horticulture?  Just post a reply in the comments with your general location.  I’ll see if there’s enough interest to pursue this further.  I’d probably try to organize this trip for sometime in late February-early March of 2011.

What’s old is new again

While the Emerald Ash Borer (EAB) continues to expand in the upper Midwest (see http://www.emeraldashborer.info/files/MultiState_EABpos.pdf  for a current infestation map), EAB is old news here in Michigan, especially in the southeastern part of the state.  Efforts to restore urban and community forest canopy lost to EAB will continue, however, for the foreseeable future. In 2003 we established an Ash Alternative Arboretum MSU Tollgate Education Center in Novi, MI – which is near ‘Ground Zero’ for the EAB infestation in North America.

 

The planting offers some insights into selecting alternative landscape trees to replace ashes.  A couple of elm cultivars, in particular, have emerged as shining stars in the demonstration planting that includes five specimens of 37 different species and varieties.  All trees were planted as 1½”-2” bareroot liners by Tollgate volunteers.  Tollgate farm manager Roy Prentice has overseen the maintenance of the planting.

 


Accolade elm (Ulmus japonica × wilsoniana ‘Morton’)  Compared to most of the other selections planted in the arboretum at Tollgate, Accolade elm looks like a man among boys.  Growth of these trees has been outstanding – the trunks of the trees have grown fast enough that they have split off their plastic rabbit guards (see photo).  Like Triumph elm, Accolade elm has dark green glossy leaves and develops into a large tree.  Although elms are often thought of ‘ugly ducklings’, both Triumph and Accolade are quickly developing well-formed vase-like crowns.

 


Triumph elm (Ulmus ‘Morton Glossy’) has also done very well at the Tollgate planting.  This elm develops a vase-like crown with age and has dark green, glossy leaves.  A large tree to 55’.

 

The elms are part of series of elm cultivars that have been developed with high tolerance of Dutch elm disease.  Most of the new elms are hybrid crosses with Asian and European elm species, though selections of American elm that are tolerant of Dutch elm disease are also available in the nursery trade.  The irony in all of this, of course, is that native American elms were devastated by another introduced exotic pest, Dutch elm disease.  As elm trees were rapidly lost during the 1950’s, 60’s, and 70’s, ash trees became a popular replacement due to their ease of transplanting, growth rate, broad site tolerance and pest resistance (yet another irony).  Now we’re promoting elms to replace ashes.

 


Street scene before and after Dutch Elm Disease.  Photo: theprincetonelm.com

The moral of the Dutch Elm Disease and Emerald Ash Borer stories is that it’s critical to avoid over-reliance on one species or even one genus – even a native one.  In Michigan some of our urban and community forests are over 50% maple.  As global trade increases and the potential for destructive pests to hitch-hike around the world rises, the best hedge against catastrophic tree loss is to plant a broad and diverse array of adapted trees.

Shear lunacy

I subscribe to Digger magazine, the industry publication from Oregon Association of Nurserymen.  I am always curious about trends in the nursery industry and this magazine is a good way to find out what home gardeners are buying.

The cover feature of the May 2010 issue is on topiary. While I can appreciate topiaries in formal gardens – with dozens of gardeners to keep them shaped up – I think they are poor choices for most home landscapes.  Shearing plants to maintain a particular size or shape is a never-ending activity that most homeowners will tire of quickly.  Nevertheless, the magazine reports that topiaries are becoming more popular for home landscapes, especially along the East Coast. The article showcases the newer topiary shapes – stars, crosses, angels, even cacti – in addition to the traditional spirals and poms.

The article warns growers that skilled employees are needed to prune topiaries properly, and that the time commitment to create and maintain topiaries is significant.  One grower states “it’ll take a fair amount of time to shape it, and then you’ll be trimming it lightly a couple of times a year until you sell it.”

Curiously, the article says nothing about either the time commitment or pruning skills needed for homeowners who purchase topiaries.

Even more curious…the subsequent issue of Digger is devoted to sustainability. Seems a bit of a disconnect there.