Invest in Soil for a Bigger Return

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During the past few weeks $750 million were spent on Black Friday television advertisements by marketers to get your attention. This figure does not include the money spent for print or Internet ads. This seems like a mountain of money to me, but there must be a good return on investment for these retailers.

For farmers and gardeners, the return on investment comes from the soil. Soil is the foundation for all terrestrial farming enterprises. One of the best investments a farmer or gardener can make is in the soil. Fertile soils make farming and gardening more productive.

How do you invest in soil for a bigger return? The answer is organic matter. Organic matter can be grown in place as a cover crop. Organic matter can also be added as animal manure. However, for home gardeners, adding compost to the soil is typically the most practical.

What is compost? Compost is decomposed organic material. Compost can be made from anything that was once alive. Typically, I think of leaves, shredded twigs, and kitchen scraps as good things for home composting. The key is to convert these organic materials to a stable form. Finished compost should look like rich, black, forest soil and have a good earthy smell.

Microorganisms drive the composting process. Creating an optimal environment for the microbial activity is key to quick composting. Creating this good microbial environment starts by assembling an appropriate food source for the microbes. The microbial food is the leaves, twigs, and kitchen scraps. The other two important ingredients are moisture and oxygen.

As soon as the microbial food is put together, the composting process begins. As microorganisms begin to feed, the compost pile heats up. During this phase of rapid decomposition, temperatures in the pile can rise to 130–160°F and may remain elevated for several weeks. Maintaining adequate aeration allows the pile to heat up to its maximum potential.

Once the available organic matter is consumed and microbial feeding (decomposition) slows, temperatures in the compost pile decrease, too. At this stage, the compost can be stockpiled or used.

Compost is like magic when added to soil. Adding it to clay soils helps it mellow, making the soil easier to work and plant into. Adding compost to sandy soils improves the water and nutrient holding capacity.

The easiest way to start composting is to make a pile about 4 feet in diameter and about 4 feet tall. Build it in layers starting with a 10 inch layer of coarse woody debris and brown leaves. Then add a 6 inch layer of nitrogen rich material like grass clippings, coffee grounds, kitchen scraps, or a handful of 10-10-10 fertilizer (about ½ cup). Then for the third layer, add an inch or so of soil or finished compost. This soil/finished compost layer seeds the pile with hungry microbes. Keep building the pile by alternating the three layers until the pile is about four feet high.

Don’t overlook the moisture content of the pile. Add water to the pile if needed. The ingredients should feel like a dish sponge that has been rung out. A good compost pile is 60% water by weight. It is not uncommon for compost piles to be too dry and the ingredients mummify rather than compost. If using dry leaves in a compost pile, you will have to add water.

Although almost anything organic can be composted, I would avoid some materials. I would not add pet feces, meat scraps, bones, grease, whole eggs, or dairy products. These can attract rodents and wildlife to your compost pile. I would also avoid adding diseased plants or weeds with seeds. If composted properly, the diseases and weed seeds should be killed by the heat. However, if the pile does not get hot enough, this could be a way of spreading weeds and disease where the compost is used.

I would also avoid adding grass clippings or hay/manure from areas that have been recently treated with a broadleaf herbicide. Some of these products can resist breakdown and remain active after composting. The herbicide label will indicate if it is a product that could remain active after composting. Be sure to read the pesticide label to avoid problems.

Good things to build a compost pile with are leaves, twigs less than ¼ inch in diameter, straw, flower garden refuse, and nonwoody plant trimmings. Kitchen wastes such as vegetable and fruit scraps, coffee grounds, and eggshells may also be added. Sawdust can also be added. However, if sawdust makes up more than 10% of the pile, add 1/3 cup of 10-10-10 fertilizer for each gallon of sawdust. The fertilizer will supply some extra nitrogen so the composting microbes have a balanced diet.

If you are in a rush for finished compost, you can turn the pile. Wait two weeks between turnings. A pitchfork works well to turn the pile.

Compost turning machine

Turning compost re-oxygenates the pile helping microbes breakdown the organic matter. This task can be difficult for a homeowner, but large scale composting operations use a purpose built machine like this one at Earth Farms Organics in Dallas, NC.

At the end of eight weeks and three turnings, the pile should be 1/3 of the original height and the product should be black and have a good earthy smell. If you are not in a rush, just give it several months to decompose before using.

Besides improving soil, composting is a good way to recycle waste. Instead of hauling away leaves and throwing away kitchen scraps, turn this into a soil investment. This will save you money and will make your garden more productive.

Now is a great time to get started composting. If you want to read more about composting, visit (http://content.ces.ncsu.edu/composting-a-guide-to-managing-organic-yard-wastes). If you have questions, please email me at seth_nagy@ncsu.edu or contact the Caldwell Extension Center at 828-757-1290.