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Welcome the recent rain, now monitor soil moisture

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Thursday, June 4, 2015 3:54 PM

With all the recent moisture (2.5 inches since the first of April), it’s easy to get excited about gardening.

After a relatively dry and warm winter, pessimism abounded, and it was easy to cast a dark cloud (that didn’t produce any moisture) over the growing season. And while the rain doesn’t really replace the snowpack, it does wonders for our soil moisture.

As air temperatures (hopefully) start the climb into the 70s and 80s, our soil temperatures will follow suit, and the majority of our garden plants like warm soil. You may be brave enough to transplant your tomatoes outside, and if air temperatures don’t go below freezing, then they should survive. However, it doesn’t necessarily mean they will grow.

Soils put the majority (90 percent) of their energy into drying rather than warming. In an ideal garden bed, the rain and snow will bathe the soil particles but will drain relatively quickly. That can be a challenge in our clayey soils, as they tend to hold onto water longer than a sandy, or silty, soil. And it can be even a greater challenge when the spring is cool and wet.

Welcome to reason No. 347 why gardening – or farming – can be a challenge in our environment: We like the soil moisture, but we want our soils to drain quickly so they can warm themselves, so we can plant our beloved tomatoes – and potatoes, squash, corn, beans, peppers and zucchini. Even our cold-season crops – carrots, lettuce, spinach and peas, for example – will only germinate when soil temperatures climb about 40 degrees. So be careful when cursing the carrot seed that doesn’t seem to ever want to germinate – it may, in fact, be that the soils are still cold.

And if they are cold, most likely, they are still wet.

Ugh.

For parents (or grandparents) out there, these challenges always remind me of the children’s book If You Give a Moose a Muffin (or a Mouse a Cookie or a Pig a Pancake). While you may expect a simple outcome: soil moisture equals plants growing, emerging and different environmental conditions can change that end result. Ultimately, you may get tomatoes, but the pathway to get there just may not be a straight line.

To get our soils to drain more quickly, and consistently, gardeners can do a couple of different things. First, raise the height of the bed. A raised bed allows water to percolate at a faster rate. This may mean that you have to irrigate more often, but when it comes to vegetable gardening, especially when trying to germinate seeds, you controlling the water, rather than Mother Nature, has its advantages.

Secondly, add organic matter. As my master gardeners can attest to, I constantly preach the benefits of organic matter. This may come in the form of compost, manure or soil amendments, but regardless, the attributes of stable organic matter (humus) abound:

It “glues” soil particles together, forming larger aggregates, which in turn creates larger soil pore spaces for improved air and water infiltration and movement.

It improves water retention and release to plants.

It can moderate and stabilize the soil pH.

And it can create a favorable environment for beneficial soil organisms – bacteria, fungi (rhizobia and mycorrhizae) – to do their dirty work: improving soil tilth and making nutrients available to plants.

parmenterdm@co.laplata.co.us or 382-6464. Darrin Parmenter is the director and horticulture agent of the La Plata County Extension Office.

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