Thursday, February 21, 2013

Horti-Culture Shock

Posted by Eric Hammond, Adams County Extension
I’m in the process of going through a radical change in my horticultural life and it’s kind of stressing me out.

Several years ago, after my wife and I got married we moved into a house located in old town Fort Collins.  It’s a tiny house (800 ft2) on a big lot and is nearly ninety years old.   Among other advantages this location is a great place to garden.  The neighborhood is buffered from temperature extremes by the mature landscape.  In the backyard the soil was clay loam with moderate pH of 7.0 and had an organic matter content just above 3% at the time we moved in.   I was shocked how easy it was to work.   We put a lot of work in to the landscape and had a lot of success.  Large vegetable garden  plots, low water use perennial boarders, fruit trees, raspberry and black berry brambles, grape vines, an herb garden and new ornamental trees in the front yard- we had a bit of everything.     

We recently moved.

For work-related reasons we now are living a new subdivision in a house with a (mostly) pre-installed landscape.   The site is more exposed and, though I’m still waiting on a soil test, I’m not holding my breath on a neutral pH and high organic matter content.   And the compaction….

From an engineering perspective it turns out the ideal soil to place construction on is strong, stable and well drained (go figure).   For most soils the most cost effective way to improve the first of those two properties is through compaction.  During construction a soil is compacted by running heavy equipment over its surface.  This pushes the mineral particles of the soil closer together reducing its volume. Primarily, this eliminates large pore spaces within the soil.  These are the pores which under non-saturated conditions would normally be filled by air. One way to visualize compaction is as the air being pushed out of a soil.   
Padfoot drum soil compactor                              

So what condition does this leave our new soil in terms of potential for plant growth?  We likely have a soil which drains slowly (has a relatively high proportion of small pores), is poorly aerated (has few large pores spaces) and is low in organic matter.  Compaction, by increasing a soil’s strength, also has the effect of making a soil harder to for roots to penetrate.  This, along with reduced aeration, restricts the potential rooting area of plants which in turn limits the availability of water and nutrients.   

 I’m already feeling bad for the plants I’m going to put into my yard in the spring. 

On a personal level, the trauma has already begun as I find myself dealing with abandonment issues related to our old landscape.  I occasionally find myself in Fort Collins for work or visiting friends.  On such trips I have to fight the urge to drive by our old house and check on the plants.  Thoughts start running through my head: “Are they winter watering the grapes along the fence?  Do they even know they need to?  Maybe I should just stop by and knock on the door and let them know that it’s a good idea.   If they are not home I might just drag a hose out there and give them a little bit of water.  That would be considerate right?”  It is at this point that I realize if I substitute “weird” for “considerate,” this line of thought is really much more reasonable and I studiously avoid driving by the house.

In an effort to work though my issues, I’m trying to stay positive and keep looking forward.  So, I’m forming my plan of attack for the coming gardening season.   What can be done to improve soil conditions in a landscape?  Well that’s broad topic- books have been written on it.  The simplified version is that it is often necessary to employ a three pronged approach using aeration (or cultivation), the addition of organic matter and patience.  Aeration to physically break up the compacted structure, organic amendments help aggregate the mineral particles of the soil, and patience because it may take several years to achieve results.  Patience…..ugh, but it really is critical. There is no amount of labor and no amendment you can buy that will improve a soil overnight.  In fact, if you cultivate the soil too often or under the wrong conditions you can actually destroy soil aggregates.  Similarly adding too much organic matter or the wrong type (for example un-composted manure) can lead to excess nitrogen and accumulation of salts.

So, as spring approaches I’m trying to stay patient and positive.  There a lot of people who face the challenges of gardening in a new landscape who come into the Extension Office with questions.  Now I will have firsthand experience with their issues.  Plus, think of how much more I will appreciate the landscape and the fruits of the garden having worked harder to achieve them!  Gardening on compacted clay soils mixed with assorted inert rubble and trash is going to be a really a good experience!  Ah self delusion, you are a comfort. 

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