Composting

Composting is a good way to reuse our natural resources, recycle nutrients and add good organic matter back into the soil.  

The popular practice of composting is defined as the process by which organic materials biologically decompose under controlled conditions. Perhaps the most notable point about composting is not to make it more complicated than it is.  By merely throwing a pile of twigs and leaves in the back corner of the garden, you are composting; of course, it may take a year or so to breakdown.  But by following a few simple rules you can speed up the process and produce good compost in about a month or so. The following are key principles:

 a. Proper moisture and air (oxygen) content - Compost works best if the moisture content of the materials is about 50%.  That’s not easy to measure, but it has been estimated to be approximately the moisture content of a wrung-out sponge.  If the material is too dry, decomposition will stop; if too wet, oxygen is excluded, and decomposition will slow and may smell bad. 

b. Proper carbon/nitrogen ratio - For effective composting, the raw materials must have a proper carbon/nitrogen ratio – set at about 30:1.  Since this too cannot be easily measured, mixing equal volumes of green plant material with equal amounts of brown plant material will give this ratio. The greens are fresh moist materials like grass clippings, weeds, manures and kitchen scraps. The browns are dry materials such as twigs, wood chips, straw, saw dust and paper.  If a pile of twigs are thrown to the side, they will eventually decompose. When leaves (greens) are combined with the twigs (browns) in the proper ratios, decomposition will occur more rapidly.    

Mixing grass clippings with twigs or chips is not only good for obtaining the proper ratio but also helps to maintain a good oxygen level.  Grass clippings or shredded papers alone tend to mat and exclude oxygen.  Adding twigs helps to open the pile allowing a better movement of air.   

c. Proper size of material - Soft, succulent plant tissue doesn’t need to be chopped into small pieces because it will decompose rapidly. Woody materials, however, will decompose better if pieces are ½ to 1 ½ inches in size: the smaller the pieces the quicker the decomposition.

d. Proper pile size - The size of the compost pile is important.  The minimal size is 3 cubic feet (3x3x3). Maximum size would be around 5x5 and as long as desired.

e. Proper turning- Turning the pile is not required but will certainly speed up the process if turned every day to every ten days. Turning helps ensure proper air circulation, moisture and heat distribution. 

What should NOT be put into the compost pile? Meat, fat, manure from meat-eating animals as well as human waste. Manure from herbivores such as goats, cows, horses, rabbits and even elephants can be used.  Don't throw diseased plants into the compost pile, because the pile may not reach the temperatures that are required to kill plant diseases and weed seeds. 

Finally, here’s how to know when the composting is ready: the majority of the pile has become dark, loose, crumbly and sweet smelling.  Also, the original materials will not be recognizable with the exception of a few pieces of tough woody material. 

Composting Produces Good Organic Matter

By following some simple rules you can speed up the processing time and produce good compost in one to two months. Some ‘experts’ can even turn a pile of garden waste into nice compost in as little as 14 days.  Here are the essentials:

A. Proper moisture and air (oxygen) content - Compost works best if the moisture content of the materials is about 50%. That’s not easy to measure, but it has been estimated to be about the moisture content of a wrung-out sponge.  If the material is too dry, decomposition will stop; if too wet, oxygen becomes limited, decomposition slows, and foul odors will be produced.

B. Proper carbon/nitrogen ration - For effective composting, the raw materials must have a proper carbon/nitrogen ratio – set at about 30:1.  Since this cannot be easily measured, experience has shown that mixing equal volumes of green and brown plant material will give this ratio. The 'greens' are fresh, moist materials like grass clippings, weeds, manures and kitchen scraps. The 'browns' are dry materials such as twigs, wood chips, straw, saw dust and paper.  If a pile of twigs are thrown to the side, they will eventually decompose. But when leaves (greens) are combined with the twigs (browns) in the proper ratios, the organic matter will decompose more quickly.    

Mixing the greens with the browns is not only good for obtaining the proper ratio, but also helps to maintain a good oxygen level.  Grass clippings alone (shredded paper too) tend to mat and exclude oxygen.  Adding twigs helps to open the pile allowing a better movement of air.   

C. Proper size of material - Soft, succulent plant tissue does not need to be chopped into small pieces because it will decompose rapidly.  However, the harder to decompose woody materials will compost best if pieces are ½ to 1 ½ inches in size: the smaller the pieces the quicker the decomposition.

D. Proper pile size - The size of the compost pile is important.  The minimal size is 3 cubic feet (3x3x3). Maximum size would be around 5x5 and as long as you want it.

E. Proper turning - Turning the pile is not required, but will certainly speed up the process; turn any time from every day to every10 days. Turning helps ensure proper air circulation along with good moisture and heat distribution. 

Finally, here’s how to know when the composting process is finished: when the majority of the pile has become dark, loose, crumbly and sweet smelling.  Also, the original ingredients will not be recognizable with the exception of a few pieces of tough woody material. Composting is a good way to reuse our natural resources, recycle nutrients and add good organic matter back into the soil. 

Healthy Soils

Healthy soils are full of life. This life is comprised of literally millions of different species and billions of individual organisms both large and microscopic. Forty million bacteria can fit on the end of one pin. Other microbes include algae, protozoa, yeasts, fungi and nematodes. Some of these organisms feed on dead organic matter, while others feed on other microorganisms. As a group, they help to recycle nutrients, build the soil structure and most important, help to convert organic matter into rich, stable humus. It is the humus which is the life support system of the soil.

The following soil problems can be corrected by adding humus:

1. compacted soils,
2. fluctuating pH levels,
3. infertile soils,
4. sandy soils 
5. clay soils and
6. in addition, a soil rich in humus will help reduce pest insects and disease pathogens in the soil.

How do soil organisms build better soil? 
Bacteria – feed on organic matter, store and cycle nitrogen and decompose pesticides.

Fungi – some feed on dead organic matter like crop residues; others are parasites that attack other microbes. Some live in association with plant roots delivering nutrients to the plant.

Protozoa – eat bacteria, fungi and algae. The consumption of bacteria slowly releases nitrogen into the soil. Protozoa also convert organic nitrogen, not available to plants, to nitrogen forms which are available.

Mites – decompose organic matter.

Nematodes – these microscopic worms eat other worms in the soil and are an important part of the nitrogen cycle. Some nematodes attack plant roots but most are non-pathogenic.

Earthworms – expel partially decomposed organic matter which produces  nutrient rich casts. In addition, the worms create some small tunnels which aid in the development of good soil structure and water movement in the soil.

Gnats - Nuisance Pests

Adult fungus gnats are primarily a nuisance pest, although some damage can be done to plants due to larval feeding on root hairs. This type of damage can be serious in greenhouses and nurseries.

Fungus gnats thrive under moist conditions, particularly where there is an abundance of decaying vegetation, algae, and fungi. They infest the soil and container media, specifically those rich in organic matter. Fungus gnats do not bite people or animals and are not known to carry human pathogens. They have a beneficial role as decomposers helping to convert dead vegetation into nutrients for plant growth.

The adults are dark in color and similar in appearance to mosquitoes. They are about 1/16 to 1/8-inch long, although they can be larger. The gnats are relatively weak fliers and are usually not found flying around indoors.

Females lay tiny eggs in moist organic debris or potting soil. The immature, legless larvae have a white to clear body with a shiny-black head and when fully grown are about 1/4 inch long. The larvae live in the soil and feed on organic mulch, leaf mold, grass clippings, compost, root hairs, and fungi.

Control

Cultural and physical control includes reducing moisture as much as possible, eliminating any plumbing or irrigation system leaks and providing good drainage. Moist grass clippings, other organic mulches and composts are favorite breeding spots. The use of partially composted matter in potting mix will encourage the infestation of gnats.

Insecticides are used in commercial plant production but are seldom warranted to control fungus gnats around the home.  Bacillus thuringiensis subspecies israelensis (Bti) applied to the soil or potting soil is a safe product for the control of fungus gnats. Repeated applications are needed for long-term control. Note: This particular Bt product is different from the one used to control caterpillars. Bt labeled for caterpillars is not effective against fly larvae. Insect growth regulators (kinoprene, cyromazine) applied to the potting mix can also be effective.

Pyrethrins or a pyrethroid (bifenthrin, permethrin) are an option to provide temporary, fast-acting control. Pyrethrins have low toxicity to people and pets. When spraying houseplants, it is best to move the plants outdoors for treatment and wait a day or so before bringing them back inside.

Biological Control - Predators, such as some beetles, mites and nematodes will help to control fly larvae outdoors.   

Reusing Potting Soil

When replanting in containers, should the old potting soil be recycled?

Reusing potting soil can work for a while; it can be rejuvenated each time by adding some nutrients and perhaps some organic matter. If a pathogen, however, whether fungal, bacterial or nematode, is introduced by way of an infected plant, the whole pot is contaminated and subsequent plantings are at risk of being infected. Have you ever planted seeds in a container and nothing comes up?  This is one reason why. 

Sanitation is important both for commercial operations as well as for the backyard. Buying new potting mix each time is the best solution. Since this can become costly, the question arises, “Can I clean up or sterilize used soil?” Here are three methods:

1) Solar sterilization, putting clear plastic over a pile of soil and allowing it to bake for 4-6 weeks, is a good idea in some locals since warm weather is required. 2) Steam sterilization is quite effective, but one must have access to steam. 3) Lastly, and perhaps the most practical for small quantities of mix is the oven. Here are the directions: place slightly moistened soil mix in a covered pan and bake in the oven at 250 degrees F for about 45 minutes.  The center of the mix needs to reach a temperature of 180 degrees F for at least 30 minutes; use a candy or meat thermometer to check the temperature.  This process may produce an unpleasant odor.  

Used potting soil can be thrown in a garden compost pile. Alternatively, a designated pile of used potting soil only can be created. When the process is complete, the soil is able to be reused for container purposes. This procedure will be relatively safe if either compost pile heats to proper temperatures, and the heating is uniform. Ideal temperatures range from 104 F. for 5 days to 130 F. for 4 hours. 

If potting soil is reused, I would recommend a type of crop rotation. Whether vegetables or annual flowers, replanting with the same species of plant or even in the same family is not advisable. For the next planting, rejuvenate the soil and plant with a different family of plants. In conclusion, gardeners have been successful in reusing soil mixes; nevertheless, the above information is useful for making an informed decision.

Organic Weed Control

Cinnamon, clove and thyme oils, acetic acid (vinegar), citric acid, d-limonene (a component of the oil extracted from citrus rind) and lemongrass have all been used as an organic approach in controlling weeds. They are strictly contact herbicides with no residual activity; good coverage is essential. These products are most effective on small annual seedlings; weeds in the first true leaf stage are easier to control. They are also more effective on broadleaf weeds than grasses.  These compounds will burn the tops of perennial weeds, but they will quickly recover.  Repeat applications are needed for perennial weeds.

This type of herbicide will damage any green vegetation they contact but are safe against woody stems and trunks.  In general, the organics listed above do a moderately good job. In trying to control weeds in large areas like acres, however, the economics of using these products is poor. It is expensive.

Many of the organic herbicides work better when temperatures are above 75 Fahrenheit; sunlight may also improve the effectiveness of some.

Adding a spray adjuvant, a product added to the herbicide mix to enhance the effectiveness of the herbicide, will result in improved control. 

As stated, the age of the weed is important, the younger the better. A group of organic herbicides were tested and found to control broadleaf weeds between 80 to 100 percent when the weeds were 12 days old. But after 26 days of age, control was between 17 and 38 percent. For grasses, control was between 25 – 42 percent for 12 day old seedlings; for 26 day old seedlings control dropped to 0-8 percent control.

In addition to the chemical sprays, other approaches in controlling weeds include mechanical, physical and biological.  Mechanical weed control involves hoeing, hand pulling, and mowing. Burning is another mechanical method – the use of a propane tank with attached hose and nozzle. This application is best when weeds are less than three inches tall.

Physical weed control consists of placing a layer of opaque material over the soil surface.  This may include inorganic (synthetic) material like plastic sheeting, or organic material like bark, wood chips, straw and compost. Place 4-6 inches of an organic mulch for best results.  Biological weed control is where sheep, goats and geese are used to chew down the weeds.

The main point to stress is: do not allow weeds to go to seed!  Get rid of existing weeds before they flower and produce seed. The average number of weed seeds in soil is 30,000 – 350,000 seeds/square meter, or 120 million to 1.4 billion per acre.