Water Hyacinth – a friendly input in ecoagriculture

Water hyacinth (Eichornia crassipes) is one of the fastest multiplying weeds, capable of doubling within a period of 12 to 15 days. On an average, it produces 200 tonnes of biomass per acre within a short period. The best home for the weed is the stagnant water, lake, beel, ponds, dead river tributaries etc.

In the high rainfall areas like Assam, the growth of the weed is very fast. It covers most of the stagnant water bodies, more particularly in the summer and rainy seasons. Deepor Beel is the largest lake in the state of Assam. The lake is one of the bird sanctuaries in the state and various birds migrate to this place. Water bodies of the lake are used for boat transport and is a source of various commercially important aquatic plants like water chesnut (Trapa natans) etc. A group of inhabitants residing around the lake depend for their livelihood on this lake by fishing.

At present water hyacinth has covered more than half of the water surface of the lake. Massive coverage by water hyacinth causes various problems like reducing the growth of the commercially important aquatic plants, growth and development of the oxygen loving fresh water fish, obstruct the movement of water traffic etc. Severe attempts made by different organisations to control the aquatic weed failed. Neverthless, the Horticulture Research Station, Assam Agriculture University, Kahikuchi and State Institute of Rural Development (SIRD), Assam jointly have made an attempt for utilizing water hyacinth in the agriculture sector. Efforts have been made to produce vermicompost as well as use it as soil mulch.

Water hyacinth, a source of vermicompost

A study conducted at the Horticultural Research Station with different organic materials like farm waste, banana waste,   coconut leaves, water hyacinth etc. as a food for the earthworms revealed that the water hyacinth produced the best vermicompost. As per the laboratory analysis the vermicompost prepared out of water hyacinth is rich in nutrients more particularly potassium than the vermicompost prepared from other organic sources.

On the basis of these results, a vermicompost production unit was established near the lake under the supervision and maintenance of a Self-Help Group (SHG) comprising of educated but unemployed youth. Green water hyacinth collected from the lake, was chopped into small pieces, watered occasionally till partial decomposition, and later filled in the vermi composting tank. The partially decomposed cow dung was placed between two layers of water hyacinth. Locally available earthworms were used for the purpose. It had been observed that the partially decomposed water hyacinth had been converted to vermicast within a period of three months. However, the time varied according to the season. It was therefore established that the vermicompost prepared out of water hyacinth is of better quality, easy to prepare and highly cost effective. At present, the Self-Help Group is producing regularly vermicompost out of water hyacinth collected from the lake. Considering the performance of the group, it is estimated that around 6-7 similar vermicompost production units will be sufficient to utilize the water hyacinth produced in the lake.

Water hyacinth  as a soil mulch

It has been unequivocally accepted that soil mulching has several advantages like increases in moisture retention and improvement in soil biotic and abiotic conditions. Water hyacinth may be considered as one of the best among the various organic mulches like leaf mould, rice husk, saw dust etc. It is easy to collect and is considered as one of the best mulching material, particularly in crops like banana, potato, lemon etc. A study conducted at the Horticulture Research Station (HRS), Assam Agriculture University, Guwahati (Assam) on water hyacinth as mulching material on Assam Lemon, revealed improvement in soil nutrient status as well as yield. The water hyacinth produced in the ‘Deepor Beel’ lake is also being used by the farmers in potato cultivation.

N.K. Mohan, Chief Scientist, Horticultural Research Station, Kahikuchi, Guwahati-17, Assam. E mail:-mohan.NK@Sify.com

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