Soil Humus Rich Soil: A Garden Foundation

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Humus Rich Soil: A Garden Foundation

Humus is the blood, the life of your garden soil. Every gardener’s primary concern should be to make year-by-year improvements to their soil.

Soil without humus, is inactive, lacking the ability to produce quality plants and flowers. Read on to know more about humus soil and its role in creating a soil structure with rich organic matter content.

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humus soil with seeds sprouting
What Is Humus Soil?

Humus is the crumbly, loose material resulting from the decay of: peatmoss, grass clippings, leaf compost, wood chips, decayed sawdust, garden waste or any other types of organic material.

Aside from adequate drainage, soil fertility is the basic requirement for satisfying plant growth with flowers, fruits and vegetables. Actually, to most of us “good” soil IS a matter of sufficient humus.

You may also need to consider the soil capacity and type for your plant.

Loamy soils contain abundant soil nutrients making it a good choice for a wide range of plants. Clay soil on the other hand is also a good soil due to its fine clay soil particles and fertility.

Sandy soil makes another soil type. However, it has bigger particles than the first two and it dries out faster. Not enough plant nutrients exist as they get carried away especially in the event of soil erosion which usually occurs in dry, gritty and loose soils.

Humus soil contain a major component humic acid that is mainly used to supply vital nutrients to agricultural lands. Time and again when people ask me to look at their gardens, often the answer to their problems has been simply the need for more humus.

Why Is Humus Important?

Humus plays an important role in soil by retaining moisture, loosens heavy, sticky soils, adding body to light soils, helps improve drainage and soil aeration and encourages the increase and growth of soil organisms and help make nutrient components available to plants.

In the past, adding barnyard manures assured humus always being added to soils. In most places, they are no longer readily available. Now gardeners must turn to other materials, such as dried manures, green manures, leafmold, sedge peats, peatmoss, and their own garden wastes.


The garden wastes many gardeners today still fail to utilize is compost. Almost all gardens have room for a some type of compost bin tucked away behind shrubbery or the garage.

Here grass clippings, weeds, leaves, old flowers, vegetable waste from the kitchen and plants can be layered in 4 to 6-inch layers. Keep layers flat, and on top of each layer spread garden soil. As little as 1/2-inch will inoculate the pile with the necessary decay bacteria.

If you wish to hasten the decomposition, a generous dusting of any commercial fertilizer high in nitrogen can be added to enrich the resulting compost.

The pile may reach a height of 4 or even 5 feet, however at all times its top must be kept flat or slightly indented to catch and retain rain.

If the season is dry, an occasional watering will speed decay. One important point is not to add thick layers of maple leaves or grass clippings unless some coarser material is mixed with them, because they compact, and decay is inhibited.

FYI – Normally a compost pile will heat up to about 170 degrees, killing most of the weed seeds. When the compost pile is several months old, you can speed up decay and create a more homogenous mixture by slicing into it and repiling it.

When compost is crumbly and loose, the materials that make up the compost are no longer identifiable and the compost stands ready for soil work. Composting time varies with materials used, size, weather and other additional factors.

Slice down through the pile when loading it into your wheel barrow to mix it further. Spread compost 1 – 2 inches thick over your garden soil and incorporate the compost in thoroughly. You will be surprised at how your plants will respond and grow.

Humus Defined

We should define terms before we discuss the practical and essential points of how to add humus to our soils efficiently and at reasonable expense.

Many of us use the words “organic” and “humus” as synonyms. Organic material is the raw stuff from which humus is derived.

For example, if you dig two inches of sawdust into the topsoil, that is organic material. When it has decayed and has been broken down by the action of bacteria and beneficial molds, it is humus.
Makeup of Humus

I am not a trained scientist so as far as technical data is concerned, I use facts and figures furnished by scientists.

So when they say that of the elements in humus, carbon and nitrogen are two of the most important, I accept that finding.

In humus, for example, carbon frequently outweighs nitrogen by 10 to one. I read somewhere that in crop residues, the carbon may outweigh the nitrogen by several times the 10 to one ratio.

In terms of humus, what does this mean?

It means that extra nitrogen is needed, and this point is perhaps the most important one for home gardeners. For the organic materials that we add, and which change to humus, take nitrogen first – Plant roots come second.

The restoration of soil organic matter is a problem of increasing the nitrogen level or of using nitrogen as a means of holding the carbon and other materials.

Adding Organic Material

With most of us, the practical problem of increasing humus is a matter of adding organic material to the soil each year. I think natural animal manures are the best, becoming increasingly difficult to secure, are expensive and in short supply.

Let this material stand in a pile outdoors for a full year, and then add a two to five inch layer to your garden, and spade or hoe it into the top two or three inches of soil.

All good gardeners have a compost heap or else they spread materials directly on the soil for a mulch, or incorporate them into the soil. Most of us, however, do not have sufficient composting material to add the amount of organic matter we want.

Sources of Inexpensive Material?

For many the first choice is sawdust. In the northeast there are innumerable piles of sawdust and in most cases, you can get all you want for the labor involved.

One of the pleasant features in working with sawdust is that it improves all types of soils: clay, sandy, or average loam soils.



Year after year, try adding sawdust to various plots, in two, three and four inch depths and spread or hoe it into the topsoil. For each two inches of sawdust incorporated into the soil. Add a high nitrogen fertilizer to speed up the breakdown of the sawdust.

Another good way to add humus each year is an inch or two layer of peatmoss plus an inch of dried cow manure.

Peatmoss is pure humus to begin with, and that gives quicker results than when one uses sawdust. If you can secure leaf mold for the labor of getting it from a woodland, it is excellent, and usually it is not so acid as we have been led to believe.

Enough Humus?

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How does one tell if they have sufficient humus soil material to produce best flowers and crops? To get exact data, it will be necessary to have the soil analyzed, but with most of us, we will know if we can judge accurately when a soil is “spongy” with good pore space and soil structure.

The word “spongy” and the word “crumbly” fit my idea of a soil with plenty of humus. Take a handful of this type soil and it feels friendly; squeeze it, and when you jab a finger into it, the ball crumbles, yet it has good water-holding capacity. Heavy soil without sufficient humus feels unfriendly and solid; soil that is too sandy falls apart.

Keep this paragraph in mind and you will be a better gardener.

“The function of humus is to release chemicals already in the soil from the locked-up forms (fixed or in a state of fixation) in which they may exist into other forms which the feeding roots of the plant can absorb.”

“The foundation of successful gardening is basically very simple. It is a matter of sufficient humus so that the rootlets can get the nutrients needed for growth and production. A program of increasing the humus content of the soil is part of the planning of every good gardener.”

https://plantcaretoday.com/humus-rich-soil-garden-foundation.html
 

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An Introduction to Humus

by Madeleine | Tuesday, 12 Nov 2013 | BioLOGIC®, Blog, Uncategorised |
An Introduction to Humus


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There are various forms of carbon ranging from Coal which is a substance to carbon in a system which is Carbon in process. In Biodynamics, different chemical elements are described as different ethers. For instance, nitrogen is the energy ether, hydrogen is the tone ether, and carbon is the life ether. Plants, animals, humans – we are essentially all carbon-based! Hence the reason why carbon is the Life ether and why we are focusing on Humus the ultimate form of soil carbon. It is really the link between the chemical elements and soil life!

Humus is a Latin word meaning ground or earth that refers to the organic matter in the soil that has reached a state of stability where it will break down no further, and it could remain in that state for centuries. It is the second largest reservoir of carbon on Earth, the oceans are the largest.

Humus plays the key role in sustaining the living communities in the soil that are essential for healthy plant growth. Unfortunately, conventional farming has focused on artificial fertilisers which literally burn up(oxidise) the humus in the soil, destroying the micro-life and making it necessary to add larger and larger amounts of chemical fertilisers for crops to grow. Tillage is also a big contributing factor to the depletion of humus in soil. Worldwide, there has been a huge reduction in humus in agricultural soils, Organic matter analysis in show that it’s sitting at 25% of what the levels where 100 years ago! Thus, carbon that should be sequestered in the soil for the creation of more life has been lost.

Organic matter in the form of plant and animal matter is in a constant process of transformation. Raw plant and animal matter becomes active humus as micro-life digest it, eventually transforming into stable humus which is what every conscious farmer wants in abundance in the soil. It’s key to remember humus is organic matter but not all organic matter is humus! The benefits of humus are many, including:

The conversion of raw organic matter to humus provides food for micro-life so that a robust community of life can thrive
Retention of minerals – Stable humus complexes minerals and prevents losses, Humus has a CEC of 250
Humus can store these nutrients and keep them safe from being leached out by water
Draught resistance – Humus can absorb 80 to 90% of its weight in water which assists the soil in withstanding drought condition, which is critical is water-stressed South Africa
Humus helps to maintain an ideal pH by buffering high acid or alkaline soils


https://biologicwine.co.za/2013/11/12/an-introduction-to-humus/
 

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Humus Does not Exist – Says New Study

By Robert Pavlis on February 23, 2016

As a gardener we all talk about humus. Some of us even buy humus soil, and humic substances like humic acid and fulvic acid. We add compost to gardens to increase the humus level in our soils in the belief that humus is good for soil. Good garden soil is dark because of the high humus content.

If there is one thing all gardeners agree on, it is that humus is good for the garden – right?

Maybe not!

Science now says our beliefs about humus may be wrong. In this blog I will review some earth shattering news – or is that soil shattering news?


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What is Humus?

I have answered this question in a previous post, written in 2013, called What is Humus? You can review the previous post for more details, but I will summarize key points here.

200 years ago soil scientists noticed that good agricultural soil was black and in an effort to better understand this black stuff they devised a method to extract it from the mineral components of soil (ie the silt, sand and clay). They treated soil with a strong alkaline solution of pH 13. This procedure pulled the organic component out of soil so they could study them


Over time, this black substance became known as humus.

Humus has some very unusual properties. It is composed of mostly carbon and some nitrogen – not that unusual. The unusual part is that humus is very stable. In fact it takes 100 years or more for it to decompose. Microbes can’t seem to digest it even though microbes can digest just about every other organic material, including oil.

The treatment with the alkali produces two main components which are called humic acid and fulvic acid.
Decomposition Produces Humus

Lets try to understand the complete process of what happens to organic material in the garden. Organic plant (and animal) material is added to the soil. It might be added directly as leaves fall to the ground, or it might first be composted by a gardener and then added to soil. For the purpose of this discussion both processes are the same. Once in the soil, pieces of plant material are decomposed into large molecules like proteins, and carbohydrates by the action of microbes (bacteria and fungi mostly).

Over time the microbes break the organic material into smaller and smaller molecules and in the process nutrients are released for plants to use. This process takes about 5 years on average. For more details on this see Compost – What is Compost.

At the end of the process, most of the organic material has been used up by the microbes and what remains is the humus. Humus is a substance that microbes can’t seem to digest, so it builds up and remains in soil for many years. It is extremely stable, some claiming it sticks around for 100 years or more.

The black color we see in good soil is due to a mixture of organic matter that is decomposing, and humus. It is mostly humus.
Humus – Does It Exist?

The decomposition process described above has been the accepted truth for many years and was the accepted story in 2013 when I wrote my last post. But scientists have always had some issues with this story. Even 100 years ago some scientists questioned the existence of humus.


Humus could not be characterized in soil. That means that scientists could not analyze humus while it is in soil. They could only work with it after extraction at pH 13. A pH of 13 is very alkaline and at this pH all kinds of weird chemical reactions take place. Nobody could say for sure that the humus in soil was the same humus being studied after extraction.
Why Is Humus So Stable?

The decomposition process happens because microbes break apart plant materiel into smaller and smaller molecules and yet humus is immune to their digestive processes.

What else do we know about humus?

Humus is made up of very large molecules but over many years of study, no one has been able to clearly describe the structure of these molecules. That is odd given that with today’s scientific tools we can establish the molecular structure of just about everything. Humus is still defined as “a large, undefinable, quite variable molecule made up of mostly carbon and hydrogen” – that doesn’t tell us much!

Scientists don’t know what it is, and can’t explain why it is so stable.

Even more interesting is the size of the molecules. Keep in mind that microbes break down organic mater into smaller and smaller molecules. Why is that at the end of such a process we have very large molecules? These molecules did not exist in the plants when the process started. This means that they either formed on their own – which would be rare in nature, or they are created by some biological process which is completely unknown.

No one has been able to explain why and how the large molecules are created.
Humus Does Not Exist!

A very interesting paper was published in Nature, December 2015, by Johannes Lehmann & Markus Kleber, called “The Contentious Nature of Soil Organic Matter”, ref 1. For those not familiar with the magazine Nature, it is one of the top scientific magazines that tends to publish the creme-DE-la-creme of new discoveries. It is extremely well respected.

I’ll explain the details below, but what this paper says is that we have been looking at humus the wrong way for 200 years. Humus does not exist in the soil. Humus is created during the pH 13 extraction process. The strong alkali creates humus.

There is organic matter in the soil. When it is treated with a pH 13 solution, it goes through a process which creates the large humus molecules.
The New Decomposition Model

Using the information provided in the above mentioned paper, I’ll re-describe the decomposition process.

Organic plant material is added to the soil. Once it is in the soil, pieces of plant material are broken into large molecules like proteins, and carbohydrates by the action of microbes.

Over time the microbes break the organic material into smaller and smaller molecules and in the process nutrients are released for plants to use.

Organic matter seems to decompose slowly for two reasons;

molecules interact with soil, in effect hiding from the microbes
microbes build large molecules making the process start all over again

Large molecules of organic matter interact with soil more than previously thought. In fact the soil tends to hide the organic matter from bacteria to some extent, slowing down the decomposition process.

The second important point is that microbes use small molecules and build them up into large molecules, just like plants do. They take simple sugars, nitrate and phosphate and build proteins, DNA and carbohydrates from them. This is not new information, but the paper suggests that this process is much more significant then we realized. Microbes slow down the decomposition process by making it start all over again.

At any given time, soil contains a wide range of molecule sizes – The Contentious Nature of Soil Organic Matter – the title of the research paper.

There is a steady stream of large molecules entering the system when new plant and animal material is added to soil and by the death of microbes. This organic matter is constantly being decomposed into smaller and smaller molecules eventually turning into simple nutrients like nitrate and phosphate, as well as carbon dioxide.

Soil does not contain humus, as previously defined. There are no large stable humus molecules and there are no humic and fulvic acids. Humus and the associated acids only exist in the test tube after soil is treated with a pH 13 solution.
What Does This Mean For The Gardener?

It does not change a lot for the gardener. We already knew that it is important to add organic matter to soil – that has not changed. We know organic matter feeds the plants over time. We know it improves soil structure by creating aggregates.

As explained in my post What is Humus?, you can’t buy humus even though a lot of people sell it. What they are selling is just organic matter with a fancy label and probably a higher price tag.
Humic Substances

The term humic substance is used as a catch all for a number of products including humic acid and fulvic acid.

We now know that these are created in the extraction process and are therefore man-made chemicals. Contrary to common belief, humic substances are NOT organic (in the sense of organic gardening).

Do they work? Do they add any value for plants? Sounds like a topic for another post – but the short answer is that their may be some value to them – but the scientific evidence supporting a real value in the garden is weak at best.
The Scientific Process

There is a lot of negative press these days about science and the scientific process. Everything is controlled by Monsanto, and all the scientists are paid to lie about their results. Anyone with half an ounce of common sense knows this is bull.

Science is not always right. With humus they were wrong for 200 years. Part of the reason for this is that soil science research is not funded very well – but 200 years is a long time.

The issues about humus were raised as early as 1888 (ref 1), but they were dismissed. They were again raised 50 years later and were again dismissed. Now it seems that there is more support for the idea. Part of the reason for this is that we now have better technology which should be able to detect humus in soil, but it can’t find any.

The important point of all this is that science research is a self correcting process. Over time mistakes are corrected by new studies. The system does work. Over time science does reach the right conclusions. We have just observed for the first time, the gravitational waves predicted by Albert Einstein in 1916. Science may be slow at times, but it is much better than the alternatives.

Is this the end to the humus story? Probably not. The paper I am discussing is very new and not all scientists agree with it. It is quite possible that in another 2 years I will write about humus again and change the story, but I don’t think so. The issues with the old humus story are now clearly explained, and the new theory fits the data we have.

References:

The Contentious Nature of Soil Organic Matter: http://www.nature.com/nature/journal/v528/n7580/abs/nature16069.html
Photo Source: The Contentious Nature of Soil Organic Matter



https://www.gardenmyths.com/humus-does-not-exist-says-new-study/
 

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Manage Carbon

6 Spoke Wheel

The sixth spoke is carbon management. Carbon is not considered to be a plant nutrient and yet more than 40 percent of a plant is carbon (on a dry matter basis).More important Compare this with typical macronutrient contents of 1.5 percent nitrogen, 1 percent potassium, and 0.2 percent phosphorus. Farmers are really 'carbon managers' - they use plants to absorb carbon dioxide from the atmosphere and convert it into many different compounds, some of which are harvested (See figure below). A large portion of the carbon absorbed is used to feed soil organisms through the living roots. This carbon in the soil is of particular interest because it has such a profound effect on soil health.


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A soil with high organic matter content is a good indicator of soil productivity. In the past this was called 'humus.' It is now recognized that humus is the highly stable form of carbon, and plants feed soil organisms with non-stable carbon compounds that are quickly consumed but contribute to the growth and activity of the entire soil food web. The below-ground part of the plant is probably more important than the above-ground part for increasing humus content. Therefore, it is important to have living roots in the soil year-round and return organic materials such as crop residues and manure to the soil. It is also important to limit soil disturbance because research has shown that large amounts of carbon dioxide are released when the soil is disturbed. The greater the volume of soil disturbed, the greater the carbon lost from the soil.



Maintaining a proper balance of carbon and nitrogen in the soil is very important in a healthy soil. As carbon is produced, a source of nitrogen needs to be available to provide the nutrients that microbes need to break down plant materials high in carbon, such as corn stalks or small grain straw. Rotations need to include legumes and soil organic matter content needs to be increased so that the soil has a larger source of nitrogen that can be made available when organisms and crops most need it. Using cover crop mixtures of both legumes and grasses is another way of providing microbes with both carbon and a nitrogen source to break down the carbohydrates and increase the level of organic matter in the soil.


https://www.nrcs.usda.gov/wps/portal/nrcs/detail/pa/soils/health/?cid=nrcseprd1201408
 
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