Monthly Archive for February, 2012

Soil Basics, Part 2

Published on February 24, 2012 in Gardening Basics. 0 Comments Tags: gardening basics, soil, soil management.

I hope that last week’s blog post on soil was helpful. Whether the information was a review or new, it gives you something to process and possibly plan a new strategy for improving your own soil. I know that I am! This week I would like to continue to explore soil and specifically four important aspects of it.

First, soil is full of life! There are live plant roots, earthworms, insects and a whole host of microorganisms that cannot be seen. In ¼ teaspoon of soil, there can be as many as 1 billion microorganisms, and they are the most abundant in the root zone. Their main function is to break down plant remains, and this break down process releases nutrients and creates soil organic matter. It is a diverse population, and many of the organisms are beneficial such as mycorrhizae fungi and rhizobia bacteria. Others are not beneficial and can cause disease and damage. Microbial populations are the highest in soils that are warm, moist, and have organic matter. Good practices to keep the microorganism populations high and performing well are adding organic matter annually and growing a winter cover crop each year.

Second, soil pH measures the acidity or alkalinity of a soil. Why is the pH important? It affects the availability of plant nutrients and it affects the activity of soil microorganisms. In arid climates, soils tend to be alkaline, and in rainy areas, soils tend to be acidic. The middle of the pH range, 5.5 to 7.5, is where most plants perform the best (with a few exceptions) and where microbial activity is the highest. Here’s a chart that shows the effect of soil pH on the availability of plant nutrients.

Soil pH is important, and getting the pH tested can be done easily and inexpensively. Once your soil is tested, and you’ve determined if the pH needs to be increased or decreased, you can purchase the recommended amendment and apply it to the soil. To increase the soil pH, lime is most commonly used. To decrease the soil pH, elemental sulfur, ammonium sulfate fertilizer or urea can be used.

Third, soil salinity is another factor that can especially be a problem in arid climates. Salts can accumulate from fertilizers, composts, and manure applications. If the amount of salt reaches a certain level, there can be potentially harmful effects on plants. In areas of more rainfall, salts are leached from the soil each winter and are not accumulated in the root zone. Soil salinity can be tested for, and if the level is considered to be too high, the salt can be leached from the soil by irrigating more than the holding capacity of the soil. The excess water, draining downward will carry the salts out of the root zones.

Lastly, the fourth area is soil nutrients. On the chart above, there is a list of essential plant nutrients. To know what your soil has and what it needs, a soil test is highly recommended as well as repeating the test every 3 – 5 years.

Where do the nutrients go? Nutrients are lost when there is soil erosion, when a crop is harvested, and when there is too much rainfall or irrigation and the nutrients leach from the soils. Fertilizers are then added to increase the amount of nutrients which will improve plant growth and yield of produce.

The primary nutrients needed by plants are nitrogen, phosphorous, and potassium, and the most common deficiencies are for these primary nutrients. As a general rule, these nutrients support:

Nitrogen: leafy top growth
Phosphorous: root and fruit production
Potassium: cold hardiness, disease resistance, and general durability

What is fertilizer? It’s simply a substance that contains one or more essential nutrients for plants. Fertilizers that are commercially sold must be accurately labeled with grade, weight, and manufacturer. The grade is what gives the breakdown of minimum guaranteed percentages of nitrogen, phosphorous and potassium. Fertilizers can also be broadly classified as inorganic or organic.

What’s the difference between the two? Here is a chart to help explain the differences:

	Organic Fertilizer	Inorganic (Processed) Fertilizer
Source	Natural materials; little or no processing	Manufactured or extracted from natural materials
Examples	Manure, cottonseed meal, rock phosphate, fish by-products	Ammonium sulfate, processed urea, potassium chloride
Nutrient availability	Usually slow-release; nutrients are released by biological and chemical processes in soil	Nutrients usually are immediately available to plants
Nutrient content	Usually low	Usually high

Here are some fertilizing basics:

Always read the label!
Apply fertilizer before anticipated plant growth
Nitrogen applications have its greatest effect for 3 – 4 weeks after application
Use a liquid fertilizer when starting plants to provide phosphorous to new roots
Do not apply fast-release fertilizers prior to heavy rainfall or over irrigate after application
Do not apply fertilizers around wells or where run-off could carry into waterways
Calculate how much you need (based on soil test and plant needs) and do not use more than needed

Some natural practices to maintain nutrient rich soil:

Add organic matter, 1 – 2 inches to soil each year. Organic matter is a long-term, slow-release storehouse of nutrients which continuously becomes available as the soil microorganisms break it down.
Make your own compost or purchase commercial compost for your source of organic matter. Composting deserves its own blog post at a later time!
Make use of green manure or a cover crop each fall. Plant them as early in the fall as possible to achieve enough growth to cover the soil. Use legumes to supply nitrogen to the soil. In the spring, if it’s too wet to till under before the crop flowers, cut if off and compost the foliage for later use. The benefit of organic matter from the crowns and roots will be available when you can turn the soil under.

We have covered a lot of information in this post, and it is all fairly elementary with much more that could be written. Extension agencies are a great source of help for improving soil, and they often have free publications to address each of these four areas and more. Check out your local extension office!

Question for the week: Do you have a favorite fertilizer that you cannot garden without?

Diagram of availability of soil nutrients from: http://www.eatcology.com/index/

Chart comparing organic and inorganic fertilizer from: OSU Master Gardener text book, Sustainable Gardening

By Kimberly Bell

Soil Basics, Part 1

Published on February 16, 2012 in Gardening Basics. 0 Comments Tags: gardening basics, gardening soil, soil, soil management.

“The easiest and most dramatic way to improve any garden is to improve the soil.” Joy Jones, OSU Extension Service.

Never did I dream that I would get excited about dirt! However, my Master Gardener class on soil was so enlightening, that I actually got excited. The complexities of soil are often not understood, and we tend to overlook its significant contribution to our lives. But it is in fact, a unique habitat specifically designed to support plant life. Soil helps to provide moisture, nutrients, heat, and support to all plants. If we understand it, our gardens will reap the benefits of our knowledge! So, in today’s blog post, I want to share with you some basic facts about soil and maybe some helpful ideas to improve your garden.

What exactly is soil? This pie chart shows the breakdown of ingredients. Soil is 50% solid and 50% pore space. Of the solid portion, 45% is decomposed rock (minerals) and 5% is organic matter. Ideally, the pore space has equal portions of air and water.

Productive soil allows water to permeate it and then supplies water to the plants. Pores can be created by earthworm and root channels as well as by the aggregation of soil particles. Pores can be large (they let water permeate) and they can be small and hold water against gravity making it available to the plant roots. Soils that have a balance of large and small pores have the ability to both allow water in and the ability to hold water for supply as needed by plants.

Porosity is of huge importance to maintaining plant health, and there are factors that affect soil porosity. The texture of the soil is one factor. There are coarse and fine particles than make up soil. Sand is the largest particle and is visible to the eye. Silt is a smaller particle that is similar in size to an individual particle of white flour. Clay particles are the smallest, and they can only be seen with a microscope. Both sand and silt are rounded and look like little rocks, but clay is flattened and the particles stick together like slices of buttered bread. These particles all seem small, but the relative difference in their sizes is very large. If a clay particle were the size of a penny, a sand particle would be the size of a house!

So, pore sizes in sandy soils tend to be large and in silt or clay soils, the pores are smaller due to the particles size differences. Sandy soils are easy to permeate, but they are fast-draining and not able to retain water. Silt or clay soils allow water to be held, but they do not allow permeability.

The perfect combination of pore sizes and particle sizes would be created with roughly equal parts of sand, silt and clay. This ideal soil is called loam. Most garden soils are not ideal but a combination of sand, silt and clay in other ratios that might make the soil more challenging to work with.

Good soil structure is also vitally important to allow water and air movement. Structure is the aggregation of individual particles of sand, silt and clay. The particles will bind together with “glue” from organic matter and provide structure to the soil. If the structure is good, the soil is acting like a sponge, allowing water to enter and soak in and letting excess water drain down. However, structure is fragile and can be damaged or destroyed by compaction. Compaction will cause the soil structure to resist water movement and root penetration as well.

What causes compaction? Compaction often occurs during site preparation or house construction. It’s often difficult to establish a garden and landscape in a new housing development. Although large earth-moving equipment is not the only thing that damages soil structure. Excessive tilling or tilling when the soil is too wet can cause compaction. Heavy foot traffic or running a heavy wheel-barrow over and over will also cause compaction.

So, where does all this information lead us to? We all want productive soil that is permeable to water and is able to supply water to plants when it is needed. But, maybe we live in an area where our soil is sandy, and water soaks in but our plants dry out quickly. Or maybe we just remodeled our home and trucks hauling building supplies drove over our garden space several times. Sometimes there are just circumstances that are beyond our control.

One very important action that we can take to improve the porosity of our soil is to add several inches of organic matter to the soil each year. Adding organic matter will:

Stabilize soil structure. Humus is actually what holds particles together.
Increase water holding capacity in sandy soils.
Improve pore space in clay soils making it more permeable.
Provide nutrients to plants once it decomposes.
Provide a food source for beneficial micro organisms.

To keep soils from compaction:

Do not till or spade soil when it is too wet. It must be dry and crumbly before tilling.
Do not overwork soil with a rototiller. One pass is usually enough.
Use raised beds and paths. By using paths you limit the area being walked on and the plant roots are never walked on.
Grow a cover crop, especially one that produces deep roots like annual rye.
Increase or maintain applications of organic matter.
Aerate your soil, especially lawn areas that have heavy foot traffic.
Double dig your soil. Here’s a great video to explain this concept: http://www.youtube.com/watch?v=W85QmZgDxFk

I hope this information is useful to you. Next week, I will share some more information from my soil class on amending soils.

Question for the week: What type of soil do you have?

Diagram of soil ingredients from: http://www.vanaturally.com/guide/soil.html

Diagram of soil particle size from: http://pnwmg.org/mgsoils.html

By Kimberly Bell

Botany Basics, Part 2

Published on February 9, 2012 in Gardening Basics. 1 Comment Tags: beneficial insects, botany basics, gardening basics, pollination.

Welcome back to Botany Basics, part 2! Last week we looked at the vegetative parts of the plant (roots, stems, shoot buds, and leaves), and this week we will examine the flower of the plant which is where sexual reproduction takes place. To me, the flower is the part of the plant that is favored; it is lovely in shape, design, color and often in fragrance. Never have I really thought about why flowers are so beautiful, and maybe I’ve even just assumed that they were lovely for human enjoyment. There may be some truth to that, but an even deeper truth is that showy, sweetly scented flowers attract pollinators, and when pollination occurs, the continuation of that particular flower species is ensured. Isn’t nature fascinating and clever!?!

Here is a diagram of the flower structure from the OSU MG Program. Let’s just take a look, piece by piece and marvel at the ingenuity of its design!

The stamen is the male reproductive organ, and it contains the anther which is a pollen sac that is held on a long, supporting filament.

The pistil is the plant’s female part, and it generally is in the center and shaped like a bowling pin. The pistil is made of the stigma, style and ovary. The ovary contains eggs or ovules and once an ovule is fertilized, it will develop into a seed.

The sepals are small, green and leaf-like. They are located at the base of the flower and are there for protection and support of the bud. Collectively, the sepals are referred to as a calyx.

The petals are generally the highly colored portion of the flower. Collectively, the petals are called the corolla, and they may contain perfume.

The diagram above shows a complete flower. This means that this flower has a stamen, pistil, petals and sepals. A rose is an example of a complete flower. If any one of these parts is missing, the flower is called incomplete.

Often though, flowers are lacking parts. If a flower has both the stamen and pistil, which are essential for seed production, the flower is considered to be a perfect flower even if petals or sepals are lacking. But, if either the stamens or pistils are lacking, the flower is called imperfect. Plants with imperfect flowers may have separate male and female flowers on the same plant, or they may bear only male flowers at the beginning of the season but later develop both sexes. Also, there are some species that have separate male and female plants. In this case, male and female plants must be in close proximity in order for pollination to occur.

Pollination is the key to producing seed. It is when pollen from the anther is transferred to a stigma. This can happen through either wind or pollinators. Plant species that are colorful, patterned, and have fragrance or nectar attract birds and insects. While looking for nectar, the pollinator (like a bee) transfers pollen from flower to flower. When the pollen reaches the ovules, sperm is released and typically fertilization occurs and the ovule develops into seed.

Fruit is made up of fertilized mature ovules plus the ovary wall. Some fruit may be fleshy, like an apple, and some are dry and hard, like an acorn. Technically, “vegetables” that develop from a flower are actually fruit (ie. tomatoes, squash, cucumbers and eggplants).

So, what are some useful take-away points for us gardeners? Well, a term that is used a lot in our MG class is biodiversity. It simply means the variety of life within a specific area. If we consider our gardens and how to help them thrive, we can begin to look at what types of plants will be attractive to beneficial insects. Even if our gardening is focused on vegetables, by planting a greater diversity of flowering species amongst the vegetable plants, we’ll increase our likelihood of having a successful vegetable production. With a little planning and research we can greatly increase the chances of pollination and the reproduction of seeds and production of fruit.

To bring butterflies into your garden, plant flowers that produce an inflorescense, or cluster of flowers. Common Milkweed is a wonderful butterfly plant with sweet, nectar rich flower clusters as well as foliage that supports the butterfly larvae.
To bring bees into your garden, consider planting native perennials, like Purple Cone Flower, that are rich in nectar and pollen. Often flowers are hybridized to create qualities that gardeners want, like disease resistance, but hybridization often reduces the amount of pollen and nectar found in the flower.
Plan to have a variety of plants with different colors. Bees seem to be attracted to blue, purple, violet, white, and yellow.
Have a variety of plants for all of the growing seasons.
Do not use broad spectrum pesticides. If you have a problem with a particular pest, find a product that targets a pest or a small spectrum.

I am so glad that plants share their amazing beauty with us, and to think, their beauty is also their means of survival. Next week, my blog is going to get dirty! We will move to the next chapter in my MG course book on Soil and Fertilizers.

Question for the week: What is your favorite flowering plant and why?

By Kimberly Bell