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Search Results for ' Soil amendments'

PAL Questions: 10 - Garden Tools: 1 - Recommended Websites: 1

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Keywords: Soil amendments, Mulching, Compost

PAL Question:

Help! My clay soil is stunting the growth of my plants. I've amended the soil with compost and manure. Is there a another method of conditioning the soil that you can recommend?

View Answer:

First and most important, it appears mulching is the best organic solution for conditioning clay and heavy soils. Organic soil conditioners include compost, well-rotted animal manures, and natural fertilizers. Planting green manures such as clover, rye grass, or vetch are also effective for breaking up large clods in clay soil over time.

Sheet composting - laying compost over the entire area to be worked and using a fork (or rototiller) to work it into the soil to a depth of 2-4 inches - is cited by the resources listed below as an efficient method of soil conditioning. Both books listed below recommend repeating this process at least twice a year, in early spring and in late fall.

Secrets to Great Soil [by Elizabeth P. Stell, 1998, (pbk)] and
The Gardener's Guide to Better Soil [by Gene Logsdon, 1975, (pbk)]

The Saving Water Partnership (the City of Seattle and other government entities) has a website full of information about improving soil.

The site includes Growing Healthy Soil.

Current thinking contradicts the notion of working compost or other amendments into the soil, as explained in this March 31, 2010 Garden Professors blog post by Professor Linda Chalker-Scott of Washington State University Extension Horticulture. She specifically takes issue with the "Growing Healthy Soil" information linked above. Here is an excerpt:
"Not only will extensive digging or rototilling destroy any soil structure you might have, it will also take out the roots of any desirable plants in the vicinity). [...] improper soil amendment can cause serious problems such as soil subsidence, perched water tables, and nutrient overloads. This last point is especially important to anyone living near aquatic ecosystems, since excess nutrients always end up in the water. Before you plant this year, find out what your soil needs before amending it. And remember that mulching is the natural (and sustainable) way to add organic matter to the soil.

Season All Season
Date 2006-12-08
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Keywords: Soil amendments

PAL Question:

I have very bad rocky, clay soil. To dig in this is like prison work. We rototilled the area and put in topsoil and now it is like quicksand. I am going to build up my beds but want to break some up to get trees and other plants to take root. What are you supposed to use or do with hard clay? I love plants, and would like to get gardening, but I can't think of how to solve this problem.

View Answer:

There is no immediate solution. It may take a few years of adding good amounts of organic matter and compost to improve the soil quality. Here is some information that may help you along the way.

A Seattle Post-Intelligencer article, 'The well-made bed: Pile on the compost' by Ann Lovejoy, provides some tips for improving your soil with compost.

Washington State University Extension horticulture professor Linda Chalker-Scott has a cautionary tale on how NOT to amend clay soil, plus tips on improving it slowly over time.

Fine Gardening has an online article on improving clay soil.

Lastly, a Home and Garden Television article entitled, "Digging Rocks" may help you overcome the rockiness of your yard.

Season All Season
Date 2006-12-08
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Keywords: Prunus lusitanica, Soil testing, Soil amendments

PAL Question:

Some of my Prunus lusitanica (Portugal laurel) shrubs are changing the color of the foliage and stems. Normally the leaves should be dark green and the stems are a dark cranberry red. The soil here at the coast is very sandy. I have put composted manure (the type from bags), fertilized them, and added a bit of lime to the soil around the trunk and close to the root zone. I have not seen much of a response. Do you know what is the optimal pH for Prunus lusitanica? I am concerned about these shrubs because I just planted them last summer.

View Answer:

Prunus lusitanica tolerates a wide variety of pH and moisture levels in soils. See California Department of Forestry Selectree webpage about this plant.

According to the webpage of a local Seattle garden writer, the leaves do change color slightly, acquiring a bluish tinge in late fall to winter. She also says that Prunus lusitanica does not like wet feet.

What colors are the leaves turning? You might consider testing the soil, to make sure things are not out of balance. Here is a link to the Miller Library website's links about soil testing.

Is it possible that the bagged manure was still hot, that is, not fully aged? If so, that could cause problems.

You might also bring in photographs or sample leaves to a Master Gardener Clinic for diagnosis. You can locate a Master Gardener Clinic within Washington State at this website.

Season Summer
Date 2006-12-08
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Keywords: Soil amendments

PAL Question:

I have typical Seattle clay soil and I want to amend it before planting. I'm re-grading a large (~2000 sq. foot) area and have already added copious amounts of mulch, compost, overturned sod, etc. I'm planning on planting a cover crop of clover this summer, but before doing so thought it'd be a good idea to till in some sand. I was thinking about a level inch over the whole yard before tilling. Is there a particular chemical composition to use or avoid? How about grain size?

View Answer:

You may find this information from Colorado State University Extension on soil amendments useful. Excerpt: Don't add sand to clay soil--this creates a soil structure similar to concrete.

Professor Linda Chalker-Scott of Washington State University also debunks the idea of adding sand to improve clay soil.

For good advice on amending the soil, see these links:

Building Fertile Soil and Cover Crops for the Garden. from the University of California, Santa Cruz Agroecology Program.

Growing Healthy Soil from Seattle Public Utilities, also available in a href="http://www.seattle.gov/util/groups/public/@spu/@conservation/documents/webcontent/growinghe_200311261701557.pdf">PDF

It sounds to me as if you have already taken great steps toward improving your soil, and adding sand not only will not be necessary, but would not be a good idea.

Season All Season
Date 2007-05-02
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Keywords: Organic fertilizers, Soil amendments

PAL Question:

I was wondering if you could provide me with a more or less exhaustive list of organic fertilizers and soil amendments, their nutrient profile, and what they are good for, etc.

View Answer:

When you say 'organic' fertilizer and soil amendments, do you mean those items which are allowed under current organic regulations? I ask because there is considerable difference of opinion over what is meant by the word 'organic' in this context. Sewage sludge which contains heavy metals could be said to be organically derived, but might not pass muster in an organic garden, for example.

If you mean products which are on the Organic Materials Review Institute list of permitted soil amendments, here is a link to the list.

If you need a truly exhaustive list, I recommend looking at some of the books available in the Miller Library on this subject. Rodale's Illustrated Encyclopedia of Gardening and Landscaping Techniques edited by Barbara Ellis (Rodale, 1990) has a very easy-to-use (but probably not exhaustive) guide to soil amendments and fertilizers. Below are are some other titles:

Soils : the right way to use fertilizers, composts, soil conditioners, soil testing/problem soils 1986

Let nature do the growing : the fertilizer-free vegetable garden / by Gajin Tokuno c1986

Fertilizers and soil amendments / Roy H. Follett, Larry S. Murphy, Roy L. Donahue

Fertility without fertilizers : a basic approach to organic gardening / Lawrence D. Hills

Feeding plants the organic way / Jim Hay

Growing green: animal-free organic techniques / Jenny Hall and Iain Tollhurst

The following links may be helpful to you:

Colorado State University Extension - Organic Fertilizers

National Sustainable Agriculture Information Service - Sources of Organic Fertilizers and Amendments

University of California Santa Cruz Agroecology Program - Building Fertile Soil

North Carolina State University Extension - Nutrient Content of Fertilizer and Organic Materials (scroll down)

Washington State University Extension - Organic Fertilizers

Oregon State University - Improving Garden Soils with Organic Matter

Utah State University Extension

Season All Season
Date 2007-09-19
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Keywords: Juncaceae (Juncus family), Carex, Soil amendments, Lawns, Compost

PAL Question:

We would like to put in a new lawn around a home where there were mostly weeds. The soil is very a heavy silt because it is river bottom land. I have access to free sand; however, I've heard conflicting advice regarding adding sand to clay -- some say yes, others no. I also have access to a large supply of free horse shavings/manure from a horse stable. Would those shavings be good to add to the soil to help lighten it and add nutrients? I don't want to go to the expense of bringing in topsoil if I don't have to. What are your suggestions.

View Answer:

Adding sand to clay soil is not recommended as a way of lightening the soil, as it "may create a concrete-like structure", according to the booklet Ecologically Sound Lawn Care for the Pacific Northwest by David K. McDonald. Linda Chalker-Scott addresses the reasons for this in depth in "The Myth of Soil Amendments Part II".

Instead of adding sand, David McDonald recommends trying to till in compost. At least two inches of compost tilled into the upper six to eight inches of soil is recommended, but four inches tilled into the upper twelve inches is preferable . Try to avoid doing this when the soil is waterlogged, as it may damage the soil structure.

Composting the horse manure and shavings you have access to could be a feasible way to obtain the compost to till into the soil. Whatcom County's WSU extension has an extensive discussion of how to compost and use horse manure.They recommend curing such compost at least a few weeks before application, and suggest that one to three months is a good, typical composting time in summer or three to six months in winter.

Alternatively, according to David McDonald, if there are a few months of warm weather between autumn and seeding time, you could simply till the fall leaves and grass clippings into your soil. Depending on your planned schedule, this could be very easy. (You can find McDonald's full booklet "Ecologically Sound Lawn Care for the Pacific Northwest: Findings from the Scientific Literature and Recommendations from Turf Professionals" online as a very large PDF.)

Another option might be to consider some sort of groundcover if you discover that establishing a lawn is an excessively extensive project. Carex species or possibly Juncus phaeocephalus phaeocephalus are more naturally adapted to heavy soils in wet areas than lawn grasses and so may be less work in the end. Though they would not be appropriate for a heavy traffic area, they would be grasslike in structure. Sagina subulata might be more amenable to heavy traffic.

Season All Season
Date 2008-05-14
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Keywords: Soil amendments, Compost

PAL Question:

I bought compost from the city of Port Angeles and in a sifted wheelbarrow of compost I got three gallons of pencil diameter "twigs". These are not composted. They break/snap and are green inside. The compost was supposed to be tilled into the garden and flower beds but somewhere in the back of my mind I sort of remember that this will take nitrogen out of the soil to compost down. Is that correct or should I not be concerned?

View Answer:

It sounds like screening your compost was a good place to start; Mike McGrath recommends removing the "odd original ingredient" from compost this way in his Book of Compost (New York, NY : Sterling Pub. Co., 2006). Woody material should definitely be removed, he says. If your compost does not seem otherwise 'off' (an ammonia smell, a sulfurous smell, very odd color), sieving off the woody material is often sufficient.

Twigs compost more slowly than other material, and you could, if you like, simply re-compost them, according to the King County Solid Waste Division.

There is some debate over the effects of inadequately decomposed material such as your woody twigs in compost and mulch. Linda Chalker-Scott addresses the question of less-than-fully composted yard waste in her May 2003 myth. She agrees that inadequately decomposed yard waste has a reputation of removing nitrogen from the soil, but writes that the way the yard waste is used affects the way it interacts with the soil. As a mulch (a layer over the soil to prevent weeds or retain moisture), it does not significantly reduce soil nitrogen, but as a compost (incorporated into the soil), it may reduce nitrogen in the soil.

If you are still concerned about the quality of your compost, Stu Campbell suggests using the following techniques on municipal compost in his Mulch It! (Pownal, Vt. : Storey Books, 2001) First, test the pH, and, if it is off, store and turn the compost for several months before using it. Mature compost should have a pH between 6 and 8, which you can test using a soil test kit or some of the other options listed on Cornell University's composting pages.

Season All Season
Date 2008-06-04
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Keywords: Gypsum, Garden soils, Soil amendments

PAL Question:

Part of my yard has clay close to the surface. In addition to heavy and yearly amending with compost and other organic materials, I have heard that adding gypsum is helpful for breaking up heavy clay. Any thoughts or suggestions on this?

View Answer:

One of the most reliable resources I've found on how to amend soil is Prof. Linda Chalker-Scott, of Washington State University Extension. According to her very useful website on horticultural myths, gypsum does improve clay soil but is not the best choice for most home gardens. Here is an excerpt:

"With the exception of arid and coastal regions (where soil salts are high) and the southeastern United States (where heavy clay soils are common), gypsum amendment is just not necessary in non-agricultural areas. Urban soils are generally amalgamations of subsoils, native and non-native topsoils, and--in home landscapes--high levels of organic and non-organic chemical additives. They are also heavily compacted and layered (and gypsum does not work well on layered soils). In such landscapes, it is pointless to add yet more chemicals in the form of gypsum unless you need to increase soil calcium levels. This nutrient deficiency can be quickly identified by any soil testing laboratory for less than a bag of gypsum costs. (If you need to improve sulfur nutrition, it's wiser to use ammonium sulfate). To reduce compaction and improve aeration in nearly any landscape, application of an organic mulch is more economically and environmentally sustainable."

Washington State University says the following about gypsum as a soil additive:

"Gypsum is calcium sulfate. It is not a substitute for lime, and has little effect on soil pH. Gypsum only improves structure in soils that have extremely high sodium contents (rare in the Northwest)."

It sounds to me as if your practice of amending the soil with compost and organic matter is the best approach.

Season All Season
Date 2008-09-17
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Keywords: Ornamental conifers, Cupressus, Tree planting, Transplanting, Soil amendments

PAL Question:

I am going to take my 6-foot tall Wilma Goldcrest out of the giant pot it is currently in, and plant it in the ground. I am seeking some sort of consensus on how to prepare the hole into which the tree is going. Someone said that I should not put compost in the hole because that will encourage the roots to just stay in the area of the hole. If that's the case, then shouldn't the "no compost" rule apply to all new plantings (which, of course, it does not)? Also, when should I fertilize the tree and what kind of fertilizer should I use? I always use organic fertilizers. What about putting some bone meal in the planting hole to feed new root growth?

View Answer:

I refer you to the following information from Washington State University Extension horticulturist, Professor Linda Chalker-Scott, who discusses planting procedures in her book, The Informed Gardener (University of Washington Press, 2008). She says that the planting hole need only be the depth of the root system, but should be twice the width. She advises against amending the planting hole in any way: Backfill the hole with native soil, not a soil amendment. The idea is not to 'spoil' the plant by putting rich compost just in the hole, which will deter the roots from spreading out into the surrounding area.

Her debunked gardening myths may also be found online. These two address soil amendments and planting. She also addresses the use of bone meal as a planting amendment.

'Wilma Goldcrest' is a cultivar of Cupressus macrocarpa, or Monterey cypress. The University of California's Garden Information publication on "Pines and Other Conifers"(including Monterey cypress)says:
"Pines and conifers require less fertilizer than most other trees and shrubs. Heavy fertilizing can promote rank, unsightly growth, destroying their natural, symmetrical, picturesque form." If you do wish to use fertilizer, a dilution of something like seaweed or fish fertilizer would probably not be harmful.

Here is more about fertilizing conifers from University of Minnesota Extension Horticulture.
Excerpt:
"Why Fertilize?
The plant itself will often indicate when it needs fertilizer. If growth rate and needle color are normal for a particular variety, fertilization is not necessary. If new growth is sparse or slow, or the needles are not a healthy color, or are shorter than normal, you should probably fertilize. Keep in mind, however, it is not unusual or abnormal for newly transplanted evergreens to exhibit slow growth until they're re-established.
Regular fertilization may be recommended if you are trying to grow evergreens in a less than ideal site, such as very sandy or heavy clay soil, or if the plant has suffered damage from insects or disease. You might also wish to fertilize to encourage more rapid growth in relatively young evergreens."

Local garden writer Ann Lovejoy says the following in her book, The Handbook of Northwest Gardening (Sasquatch Books, 2007): "I rarely feed plants directly, preferring to feed the soil with what are called 'feeding mulches,' made of materials such as compost, seed meals, kelp, and fish meals."

Season All Season
Date 2009-05-23
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Keywords: Mosses--Control, Soil amendments, Mosses

PAL Question:

I have a small rooftop plant bed that's full of moss. Is that an indication of sour soil, and if so, can it be sweetened with Dolomite lime?

View Answer:

Moss is often simply an indication of a shady site or compacted soil, but can also be an indicator of low soil pH (i.e., acid soil). I wouldn't recommend adding lime without doing a soil test for pH (you can buy an inexpensive kit at most garden centers), and without considering the pH needs of the plants you have in the bed. You would not want to increase the alkalinity of the soil if your plants are acid-loving.

You may find this link about moss growing in garden beds (from Oregon State University) of interest. Here is an excerpt:
"Mosses grow in garden areas for the same reasons they grow in lawns: for example, deep shade, high acidity, poor drainage, and soil compaction. As in the lawn, mosses do not compete with other plants. Rather, they establish in bare areas where conditions are favorable (Cook and Whisler, 1994).
Mosses have not been shown to hinder the growth of garden plants or trees. Reasons for removal are generally aesthetic. But aesthetics are in the eye of the beholder, and mosses are commonly viewed as positive features in landscaping. For example, traditional oriental gardening holds distinctive roles for mosses (Japanese Garden Society of Oregon 1996; see also Encouraging Mosses). Furthermore, in some situations mosses may help reduce moisture loss and crusting on soil surfaces."

Season All Season
Date 2010-03-11
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Keywords: Soil testing, Soil amendments, Plant-soil relationships, Garden soils, Fertilizers

Garden Tool:

Successful gardeners know that healthy soil translates to healthy plants. Learn about the fine points of soil management for the home gardener from WSU Cooperative Extension.

Season: All Season
Date: 2007-07-12
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June 24 2013 12:55:25