Accelerated Composting with Wild Sunflower

Abe V Rotor

Who would think those shrubs with bright yellow flowers growing on the roadside and wastelands make excellent compost?

Wild sunflower, Tithonia diversifolia, has been found to contain high nitrogen content, exceeding nearly 6 percent, and enzymes that hasten decomposition and cut down composting time from three months to just a few weeks. This is why it is an excellent additive in composting rice hay and other farm wastes which have low nitrogen content and which normally decompose slowly.

Sunflower added in the compost pile builds heat and sustains it at a high level, 55 degrees Celsius on the average. At this temperature weed seeds and harmful microorganisms are killed, including those that cause acidic reaction. Acidic soil locks up, so to speak, nutrients that are otherwise made available for plant use.

With the addition of chopped sunflower in the compost pile, its pH value remains at 7 to 8 (neutral to slightly alkaline), throughout the decomposition period. Under this condition nitrogenous materials are immediately mineralized into ammonium nitrogen (NH4N+) and nitrate (NO3) which are directly absorb by the plants.

These are highlights of a graduate research at the University of Santo Tomas leading to a masteral degree in biological science by Luisito Evangelista, a professor at Siena College QC.

“Accelerated composting is the key to successful production of on-farm organic fertilizer specially in areas where sunflower abounds,” Evangelista concludes.

Sunflower is an alternative to Trichoderma a cellulose-acting fungus strain discovered by Dr. Virginia C. Cuevas of the Institute of Biological Sciences at UPLB especially in areas where the inoculant’s is not available.

When the sunflower-activated compost was used on Red Creole onions, yield increased by as much as 20 percent, and the physical quality of the bulbs improved. Other than being bigger, the bulbs are brighter, heavier and more uniform in size. Their neck is well closed and this is important in storage as danger of rotting is reduced.

How can one make his own sunflower compost? Here is how.

1. A well drained area, half shaded if possible, is prepared. Here a compost pile of 2 x 4 meters in dimension, breast high when compact, will be constructed.

2. The raw compost materials are prepared by chopping the rice straw and green wild sunflower separately. The ratio by weight of sunflower to rice hay is 3:1. Chicken droppings or animal manure and topsoil from the farm are also readied.

3. These materials are piled in the following arrangement: the rice hay makes the first layer, 20 cm thick. On top of it is the chopped sunflower, followed by manure and soil.

4. A second set of layers is made on top of the first, compacting the pile as the process is repeated. The pile should not be higher than 1.5 meters for convenience in watering and turning over.
5. Aeration tubes made of bamboo are planted vertically into the pile 50 cm apart. The tubes are made by partly opening the nodes, outside and inside to allow air to enter and heat to rise.

6. Temperature is monitored with a thermometer inserted through the tubes.
Heat is expected to increase immediately reaching its peak for two weeks before it gradually declines.

7. Watering should be just sufficient to maintain moisture content of 60 to 70 percent. Plastic or sacks are used to cover the pile to protect it from rain and to help conserve the heat generated.

8. As decomposition progresses the pile will shrink, and temperature will soon equal to that of the surroundings. After three to four weeks the compost is “ripe”. To facilitate, the pile is turned once or twice before it is harvested.

To know if the compost can now be used, here are the indicators.

• There is no foul odor emitted by the pile.

• Temperature has gone down and is about the same as that of the surrounding area.

• The original substrates are no longer recognizable.

• The color is dark, loamy and soft to touch.

Composting is a bio-oxidative process, which results in the production of stable organic product that contributes directly to soil conditioning and fertility. In many books it is called mineralization, that is, the breaking down of organic compounds into their elemental forms and as they settle down in the compost or in the soil as may be the case, become available to plants. This is particularly true with nitrogen. This is nature’s way of recycling chemical compounds, from organic to inorganic form, and vice versa.

Composting rice hay alone is not advisable as it has low C:N ratio. This is the reason farmers seldom convert rice hay – and also corn stover - into compost but would rather have other uses, such as roughage, if not burn them.

In terms of percentage of dry weight, rice hay contains very low nutrients - 0.86 Nitrogen, 45.91 total Carbon, 0.16 Phosphorus, 2.84 Potassium. Compare this with the analysis of dry farm manure (carabao): 1.02 N, 10.66 C, 5.33 P and 1.92 K, whereas dried wild sunflower contains 5.53 N, 55.83 C, 0.36 P, and 2.78 K. Soil on the other hand contains 0.13 N, 1.49 C, 28.36 P and 0,01 K.

It is clear that the incorporation of top soil, manure and wild sunflower in the compost pile will boost these elements – N, C, P and K - and therefore, increases the nutrient value of the finished compost.

This means that the C:N becomes closer (30:40) making it more valuable as compost, while accelerating the rate of decomposition. By maintaining moisture content at 60 to 70 percent and temperature at 50 degrees centigrade in the initial two weeks, the pH level stabilizes between 6 to 8 that are favorable to both biological and chemical reactions taking place.

Composting basically follows nature’s formula.

In nature, crop residues are left on the field after harvest and allowed to decompose or eaten by animals that in the process leave their waste on the ground. In both cases the end products become part of soil together with weeds and other plants that are normally incorporated during plowing. This may be augmented by green manuring, the planting of leguminous plants like Indigo (Indigofera hirsuta L) which is purposely incorporated into the soil before the planting season.

We may call this system traditional for the reason that it is an old practice, yet it holds the key to sustainable productivity of centuries-old farmlands. It is also common in agricultural societies throughout the world as if it evolved naturally. Traditional farming as I see it is a shared experience with man living in harmony with nature, respecting her ways and law. What judgment can we give to modern agriculture which use synthetic input and offer high production but leave the farms unproductive and spent on the long term?

Perhaps we should turn our attention to another example of natural composting. The floor of a forest is continuously being built by composting. It is a living carpet inhabited by a complex population of organisms responsible in converting organic materials into inorganic and elemental forms that are recycled to the living world, and down to the next generations of organisms.

Natural composting is also observed in insect eating plants like the pitcher plant and the sundew. It is demonstrated in the watery axils of bromeliads, which trap water and dirt. This mini pool is home of wrigglers, frogs, fish and reptiles. It is no wonder how bromeliads can live an epiphytic existence without reaching the soil for subsistence.

The ant plant is another example. Its bulbous rhizome is filled with a colony of ant that “eats” a complex tunnel network. Here inside is a laboratory that produces organic materials that the plant uses for its growth and development. This is a classical example of symbiosis.

Next time you find wild sunflowers growing around where there are a lot of farm residues that simply go to waste, think of the potential organic fertilizer that you can produce. It is the key to natural and environment friendly farming. In nature, there is nothing called waste.

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Living with Nature 3, AVR