Authors: Soumya.T.V and Anil.K.R

Coir pith or coir dust, a highly lignocellulisic material, which is produced in enormous quantities as a byproduct of coir fibre extraction industries. High content of lignin in coir pith causes very slow decomposition .coir pith takes decades to decompose there by posing environmental hazard and disposal problem. Pleurotus sajor- caju ,Trichoderma sp,and Aspergillus sp were found to be potent degraders of coir pith. Cellulosic compounds present in coir pith support initial growth of fungus and acts as a co - substrate for lignin degradation. coir waste after biodegradation can be effectively used as manure for increasing yield of crops.

Structure of coir pith

Coir pith is open cell foam; the cells are of almost uniform size and cylindrical in shape. The walls are very thin and empty cavities (lumen) are comparatively large. Average lumen size of the pith is about 50μm.Because of its sponge like structure coir pith helps to retain water and improve aeration. Aspergillus niger sp, Strptomyces sp ,Penicillium sp ,Trichoderma sp and Bacillus sp were found to be the native microflora in the raw coir pith and well composted coir pith. An additional advantage associated with Trichoderma sp is its ability as a biocontrol agent of soil borne fungal diseases.

The most preferred growing medium for plant is soil. For historic reason the farmers are mostly unwilling to switch over from soil to any other growing medium even when conditions demand. Growing environmental awareness throughout the world has triggered a paradigm shift towards designing material compatible with the environment. In developing countries the use of alternate sources to soil for growing plants is catching up. There are a no of organic medium available for commercial as well as indoor plants for the cultivation of many different crop plants .An ideal substitute for soil must have the following properties.

• It should be easily available
• Good physical properties (water holding capacity, Aeration etc) and chemical properties.
• Should contain basic nutrients
• Possibility for the addition of nutrients required for plants to be grown.
• Nontoxic to the roots and to the microorganism
• Sustain the development of microorganism incorporated for enhancing the growth of the plants and for fighting pathogen.
• Easy to handle
• Lower pH has been preferred in soil less medium since most of the macro and micro nutrients needed for the growth of the plants are available only at low pH.

The most commonly available substitute for soil in kerala is the coir pith. There are several reasons for the popularity of coir pith as potting mixture. They are

• Easy to use ,
• There is no interaction between the medium and the nutrients ,
• They offer improved availability of nutrients to plants ,
• Provide better physical and chemical properties suitable for best plant growth
• Provide a pathogen free growing environment and better ability for incorporated microorganism used as biopesticide and bionutrients.
• Lignin is a very inert material and any added soil additive and nutrients are fully available to the plants

Coir pith in its natural form is not a conducive medium for the cultivation of any crop plants. It contains lots of tannins, lignin's, Phenoloic compounds. The C;N ratio of the coir pith is also very wide and hence not favoring proper plant growth. However once the coir pith is processed the ill effects of coir pith can be overcome substantially. coir pith can be useful in soil less cultivation especially in areas facing different growing constraints such as water shortages, poor soil drainage and low fertility, soil salinity, pest and other ecological problems. In such areas coir pith plays the role of soil.

The processed coir pith has the following advantages

• It is a 100% renewable resource.
• It is light in weight.
• It's a completely environmental friendly.
• Very good water holding capacity.
• It is highly suitable for better root system
• It is easy to handle and uniform in composition
• Additional nutrients and microorganism can be incorporated into the medium so as to enhance the plant growth.
• Free from harmful microorganism including pathogens.
• Long lasting ,excellent drainage and air porosity
• Ideal pH and high cation exchange capacity and low EC
• Cost effective.

Coir pith obtained from mechanical processing of unretted husk is richer in nutrients.The unique property of this waste material is the high water holding capacity .Apart from this it is found to contain some amount of major secondary and micronutrients. The higher K content of the pith indicates the importance of this material and possibility of utilizing this as a supplier of K to the crops.

The current boom in fertilizer prices, farm energy requirements and the growing preferences for organically cultivated farm produce has necessitated the development of a programme for organic waste recycling in agriculture. About 7.5 million tones of coir pith is produced annually in India. . Though utility of coir pith has been claimed in different applications, an efficient and accepted technology for its maximum utilization is not yet made available. The composted coir pith did not contain or carry weeds and undesirable pathogens, thus providing a rich soil less environment for plant and vegetation growth. Coconut coir dust is being marketed as a soil less substitute for Sphagnum peat moss that inhibits fungus gnat (Bradysia sp) development. Plants grown in pots containing higher percentage of coir pith than soil show increased shoot and root length. Composted coir pith with the combination of mushroom and bacteria provide NPK enrichment on pot culture.This medium provides easy movement of roots and there by increased growth of plants.composted coir pith with Pleurotus sajor- caju and nitrogen fixing bacteria is an ideal media for medicinal plants. Thus using coir pith it is possible to cultivate plants organically, economically and environmental friendly ways.

Certain plants which are highly sensitive to salt content are not advisable to be grown in coir pith growing medium. Before using coir pith as a growing medium it should be tested for excess of dissolved salt and other growth inhibiting properties / ingredients .In India currently there is no systematic way to test the soil used as a potting mixture in the nurseries. Several studies have indicated that the soil in many of the nurseries contain microbial pathogen and nematodes .The planting materials for crops such as pepper, ornamental plants etc are being distributed through out kerala by the governmental and private agencies. This may be responsible for wide spread distribution of pathogens even to places, where it was not present before. In order to prevent this use of coir pith is an ideal solution. Apart from the above a large scale use of coir pith will also reduce the accumulation of this in coir belts creating environmental problems. Considering the commercial opportunities of this renewable raw material its technical possibilities and horticulture application have to be explored further.

About Author / Additional Info:
- Anil.K.R,Director, NCRMI, TVPM
- Soumya.T.V, NCRMI