Healthy Soil- Too much of a good thing?

Recently I attended our annual forum where all the Extension staff across the state come together and we learn and share.  The sharing of programs, county issues and among us plant folk, plant and soil issues are the most telling.  There seems to be a common theme this year, gardens being over amended and a misunderstanding of organics and fertilizer versus compost is evident.  Both compost and fertilizer can be organic, but they are not the same thing. 

Compost image, Colorado State

I want to point out before I go further, that Extension and Extension staff have conventional and organic options on all our factsheets and that we all care about our environment, it’s why we have the jobs we do because we are passionate about our world.  I think it is very important understand and get the facts about your soil prior to adding amendment or fertilizer.  This is very similar to practicing IPM- Integrated pest management where you observe / monitor, proper id, learn more about the issue (or system), determine action, choose tactic(s), evaluate.  IPM is monitoring the situation, gathering the facts and doing something when needed.  https://cmg.extension.colostate.edu/wp-content/uploads/sites/59/2020/01/GN-100-Integrated-Pest-Management.pdf  So think of these similar steps in your landscape and how to improve your soil.  Get the facts before applying anything and to improve when you need to improve, plant the right plant in the right place and you will be successful.  If you have never done a soil test, this is the foundation of the garden and a good place to start.  The CSU lab is currently moving so not testing currently, other great laboratories that understand our Western soils are Ward Laboratories https://www.wardlab.com/, Servitech https://servitech.com/crop-consulting/soil-sampling and American Agricultural Laboratory Inc. https://www.amaglab.com/

Once you pick a lab, stick with them as their procedures might be slightly different.  You want to be able to compare apples to apples down the road.  Please read how to take an appropriate sample and tell them exactly what you are planting (your crop): buffalo grass, tomatoes, plum tree- the more specific you are, the better the recommendation they can give you.

	University of Hawaii Soil Management

Let’s go back to the word organic.  It was first used to describe the organic matter (basically plant material: leaves, roots, stems, & microorganisms) that is in the soil.  We still use it this way, but it has also morphed into products that are naturally based.  Here I am sticking to the original definition.  Our native soils in Western Colorado are naturally 1-2% organic matter.  This is why our native plants do not prefer high amounts of compost being added to our soil, it’s not what they are acclimated to.  Then somewhere along the way organic morphed into meaning using naturally sourced fertilizers and pesticides.  We know from experience and as shown in the soil pie chart that we want up to 5% organic matter in the soil for the general typical landscape plants and vegetable and flower gardens.  When soil test results get closer to this 5% organic matter, the need for nutrients like nitrogen will drop because it is being released of some nutrients from the organic matter (plant based and microorganisms).  This article from Minnesota gives a good explanation of other reasons too much organic matter is not good.  https://extension.umn.edu/yard-and-garden-news/compost-and-soil-organic-matter-more-merrier Of course our soil is going to be different, but the having too much organic matter is the same.  We general have good minerals (phosphorus, potassium, sulfur) in our soils.  Occasionally we will see a micronutrient low due to the pH of the soil, high pH affects the accessibility of certain nutrients to specific plants.  Example: Silver maples have trouble accessing iron in high pH soils resulting in chlorosis.  Adding more iron to the soil doesn’t work unless it is chelated. 

Microbes in the soil, invisible to the naked eye-

                                                                    Colorado State
Example 2: Someone was having trouble growing vegetables, since the pH was high they continued to add sulfur, which was already at a good level.  This caused a toxicity of sulfur in the soil which causes a reduced rate of growth and necrosis.  Since we have high amounts of calcium carbonate in our soils and there already is enough sulfur, our soils are buffered which means it is very hard to change the pH so we focus on what we can change and improve.  So please do a soil sample, talk to Extension if you need more explanation, pick the right plants for your soil and you will be successful. 

Lastly, pick the right soil amendment if your organic matter is below 5%.  This includes using compost and it is ok to ask for a sample of compost and have it tested before you buy or use it.  Compost is a soil amendment, though it may help with nutrients down the road, it is not considered fertilizer or a major source of nutrients. https://extension.colostate.edu/topic-areas/yard-garden/choosing-a-soil-amendment/

If your plants are needing fertilizer, than use the appropriate fertilizer. Here is understanding fertilizer.

https://cmg.extension.colostate.edu/Gardennotes/232.pdf

Hopefully that helps in understanding that you can have TOO MUCH of a good thing.  It is like finding out that watermelon is good for you and you eat the whole watermelon, you might not feel so good afterwards.  It is important to keep things in balance.  By adding too much of one thing, other things have to become out of balance.  Look back at the soil pie chart, if there is too much water, there would be less air.  If too much organic matter, there would be less mineral particles, water or oxygen.  ALL are important. 

So hopefully if nothing else, you will do a soil sample and think about what your soil needs before you add something.

Susan Carter, Tri River Area Horticulture and Natural Resource Agent

 

 

Fire Recovery Tips

By Susan Carter, CSU Extension Tri River Area, Horticulture and Natural Resource Agent

I live in Fruita where the Pine Gulch Fire had the title of the largest Colorado fire until the Cameron Peak Fire exceeded it.  Having to respond to the effects of fire in many ways has taught me a lot this year.  Pardon me if I go off the plant topic a little on and off in this blog, but I hope you will appreciate it.

During our fire I had many mornings where the garden covered in ash.  I learned that the ash was very high pH, coming in around 11!  Seven is neutral and in Western Colorado it is common for our alkaline soils to be a pH of 8.   So 11 is very high.  So hosing or blowing off the ash so the plants would not be harmed by a loss of photosynthesis and the ash is a good idea.  I did end up with one squash plant that suffered.  If your walkways and other hard surfaces are covered with ash, sweep them off and throw it away.  Do NOT add it to the garden.  This is especially dangerous if any structures burned as then you don’t know what might be in the ash.

During Pine Gulch fire I got a question about animals, so here is the information I got from some wonderful CSU experts.  Keep your pets and backyard chickens and other animals inside as much as possible.  Clean their water often as ash can mess up their digestive systems.  Animals don’t need to be breathing the air any more than we do.  Try to watch your local air quality and do your landscaping and gardening when the air quality is not so bad.

The drought, fire and ash got me thinking about defensible space and being ready for an emergency.  My husband is a retired firefighter EMT of 21 years and fought many wildfires.  So we have items in case of emergency in our car, etc...  Make part of your gardening and landscaping thinking and acting to prevent fires around your property.   In this time of drought, wildfires could happen ANYWHERE.  We should all be prepared. https://www.ready.gov/

So how can you be prepared in the garden and landscape?  Well, I would start by removing any dead plants.  Deadhead flowers (removing flower stalks that are no longer blooming) as often these dry out.  Plus this will put my energy back in the root system of perennials and shrubs instead of working on producing seeds.  Remove leaf litter that is close to the house or in the gutters.  It just takes one ember to land in a crook of the house where there is debris and a fire starts.  You could start a compost pile away from the house to put plant debris.  Use rock mulch or other materials like flagstone, pavers, or other non-combustible materials closest to the house.  Keep wood piles and other wood products or structures away from the house.  Ideally a zone of lower growing, high-moderate water loving plants would be closer to your house as long as it does not affect your foundation. 

To create defensible space, height should increase as you move away from the house. 

See this website for more detailed information on Defensible Space. 

https://csfs.colostate.edu/wildfire-mitigation/protect-your-home-property-forest-from-wildfire/#:~:text=Defensible%20space%20is%20the%20area,modified%20to%20reduce%20fire%20hazard.&text=Develop%20these%20zones%20around%20each,buildings%2C%20barns%20and%20other%20structures.

Did you know that there are plants that are more fire resistant?  Of course some of that depends on drought and how much moisture is in the plants.  https://extension.colostate.edu/topic-areas/natural-resources/firewise-plant-materials-6-305/ .  Choose plants that do not produce a lot of litter under them.  Aspen trees would be a good high altitude garden choice over 5000 plus feet elevation, I personally recommend even higher like 6-7000’ as aspen do not do well in the low Valley’s heat and clay soil.  

Pinyon pine with twig or bark beetle damage, picture from Tri River Area

Now let’s talk drought.  I have been getting many calls about older trees not doing well.  For those of us in town with irrigation, give your trees and landscape a really good drink before the irrigation goes off.  If you live on a large properties or up in the mountains, typically there is not a lot you can do other than depending on Mother Nature for moisture.  But could you water one or a few favorite or most important trees?  If they are mature established trees, water out twice their height or spread and give them a deep soak once a month to a depth of 12-18”.  This will keep them vigorous enough to help ward of insects like bark beetles and borers.  Some trees, like pinion pines, might need some insecticide treatments to prevent ips beetle from investing.  When there are epidemics of insects and there is prolonged drought, the trees are very susceptible to attack. https://extension.colostate.edu/topic-areas/insects/ips-beetles-5-558/

For trees with lower dead limbs, removing them can decrease fire ladder potential and helps the tree to heal.  Prune evergreens when dormant to prevent attracting insects like bark beetles and borers.  Make sure you use proper pruning techniques and cut outside the bark ridge and bark collar.  For bigger limbs use the three cut method to prevent the limb from breaking and causing trunk damage. https://static.colostate.edu/client-files/csfs/pdfs/613.pdf Turn these limbs into chips or stack in a wood pile, again away from your structures.  If the plants are diseased or insect infested follow appropriate protocol for that particular issue to dispose of or prevent any spread of issues.

I hate to say it but I am hoping for an earlier winter with lots of moisture to help with the fires and the drought.  We can only do, what we can do the rest is up to Mother Nature.

How Your Soil Test Results are Like a Margarita

Posted by: Tony Koski, Turfgrass Extension Specialist

A couple of weeks have passed since you dropped off that soil sample from your yard or garden. And then it arrives: The Test Results. The bewildering assortment of numbers in units like parts per million, and millimhos per centimeter is chilling and confusing. If you are lucky, the lab has provided some interpretation of these numbers and some recommendations for fertilization of your yard or garden. You could just ignore the raw numbers and only pay attention to the fertilizer recommendations given by the lab, but for those of you who are more curious about what those mysterious numbers mean… read on my dear friends.

Here’s what your lab report will look like:

What about pH? This is pronounced “pee-H” (not “ppppppphhhht” as I once overheard).  If you live in Colorado, it’s likely that number is going to be above 7.0 (neutral). We just don’t have acidic soils like in the Midwest or east coast. Our alkaline soils (generally 7.5-8.3) means that plants such as blueberries, azaleas and rhododendrons struggle (i.e. die). There’s not much you can do to change pH. Adding pine needles, coffee grounds or sulfur are often suggested by people, but they are not effective at lowering pH. There is so much “free lime” in our soils that it is impossible to change soil pH—at least in your lifetime. Instead, take that “free lime”, have a margarita and crank Jimmy Buffet.

Since you enjoy salt with your margarita, let’s talk about EC (electrical conductivity), which is a measurement of the salts in your soil. Our example results are low; this number will be higher if you’ve added fertilizer, fresh manure or compost in recent months. Plants really don’t like salt. Check out this great blog from Dr. Ajay Nair at Iowa State University. 

Salt damage on peppers.

Vegetables tend to be most sensitive and will grow best if this number is below 2.0 mmhos/cm. If you have high EC, then plan on leaching with clean water. If you suspect you are irrigating with salty water, then testing your water is necessary (and it comes complete with another set of confusing numbers!). If your soil has a high EC value, then be careful in the future about the soil amendments you add, which can increase this number. Turfgrass can tolerate EC levels of 3.0-5.0 mmhos/cm without problem; landscape plants differ greatly in their tolerance to salts.

 

Lime estimate (seriously, why are all soil test measurements like a margarita?) is a rough indicator of the relative amount of free lime present in your soil. As mentioned above, it’s probably going to be “high” or “very high.” Only soils with “low” or “very low” estimates are worthy of consideration for acidification. Want to do a cool science experiment? Take a sample of your dried soil, pour some household vinegar on it and watch it fizz! This is the acid in the vinegar reacting with the lime in your soil.

OM = organic matter. Organic matter is the percent of organic compounds (i.e. decomposed leaf matter, grass clippings, manure, compost, plant tissues and roots, etc.) present in your soil. The magic number for organic matter is about 5%, yet this can vary widely, depending on where you tested your soil and what you have done to modify it. The longer you grow plants in soil, the higher this number will be. A 25-30-year-old lawn may have as much as 4-5% organic matter.  New, urban landscape soils may only have 0.1-0.5% organic matter (if you’re lucky). Organic matter helps “loosen” the soils, provides food for microorganisms, increases water retention, stores nutrients like phosphorous and iron and is really just a good thing. If you have a low percentage, you can increase this over time by slowly adding organic matter, preferably using high-quality compost. If you mulch your landscape with wood chips, this will also slowly increase organic matter over time (another reason to love mulch).  

The next column is NO₃-N (nitrate nitrogen). The number you see in your soil test is likely to be very different than what it was in your garden at the time of the sampling. That’s because nitrogen in soil changes rapidly from one form to another as soon as you pull the sample from the soil. This number can be very high if you sampled soon after amending with manure or fertilizing. It’s also important to note that nitrogen is the nutrient you will most likely need to add to improve plant growth, especially in turfgrass. To be honest, I pay very little attention to this number when I’m advising people on their soil test results.

Phosphorous (P) and potassium (K) are next. Phosphorous tends to be correlated with organic matter. If your OM is high, P levels will also be high. If your report comes back with low P levels, then I would challenge you to look closely at plant growth to determine if adding P is necessary.  You will never see a P deficiency on turf, so it’s totally fine that our lawn fertilizers are increasingly P-free. With vegetables, P deficiencies will result in yield reductions, so look for a number between 20-40 ppm.  One of the easiest ways to add P to a garden soil would be adding reasonable amounts of well-composted manure. Potassium levels in Colorado are usually off-the-charts, unless your soil is sandy. Adding K generally isn’t necessary in Colorado soils.

Iron chlorosis on maple.

Let’s talk about micronutrients (zinc, iron, manganese and copper).  The key point with this is “micro”, meaning necessary in very small amounts. As long as each is between 5-10 ppm, you’re in good shape. You probably hear a lot about our “iron deficient soils.”  It’s not that our soils have a lack of iron; it’s just that at our high pH iron tends to be in a form unavailable to plants. As pH increases,iron availability decreases; this is why we may see chlorosis (yellowing) on plants like maples and oaks. It’s also important to note that chlorosis can be caused by compacted, cold, wet, dry and salty soils.

The last thing to mention is soil texture. Soil texture is an approximation of the percent sand-silt-clay in your soil. It may also indicate water infiltration rate, but since the analysis doesn’t consider soil compaction, this number may not be accurate. You can’t change soil texture, unless you add different soil to your existing soil, which we strongly recommend you don’t do. 

Truly, everyone thinks their soil stinks. Even the folks in Iowa. It’s better to accept your fate, grow what you can and learn to deal with your soil’s limitations. It’s really not as bad as you think. I can only recall one or two soil test reports that made me gasp and cringe—and neither was from a homeowner’s yard. If you’re really struggling growing anything, then consider your cultural practices (watering, fertilization, tilling, mulching) or simply resort to raised-beds or containers. As Jimmy Buffet once said, “Breathe in, breath out…move on…”

For a plethora of excellent information, check out the Colorado Master Gardener Garden Notes—it’ll keep you busy until the weather warms.