Bioremediation of sodic soil through vermitech

Uttar Pradesh (UP) a northern state of India has more than 1.2 million hectares of salt affected soil, most of which is alkali affected. UPBSN (Uttar Pradesh Bhumi Sudhar Nigam Ltd i.e., Uttar Pradesh Land Development Corporation Ltd) is the nodal agency implementing reclamation programme in vast areas of UP through the application of gypsum. A novel approach to the reclamation of sodic soil was considered. Work was initiated to develop and extend vermiculture biotechnology in sodic soils.

A five year project was started in 1996 with Uttar Pradesh Bhumi Sudhar Nigam, Lucknow (UPBSN), the Institute of Research in Soil Biology and Biotechnology, and The New College, Chennai (IRSBB) as the major partners. The major activities include(a) culturing of earthworms, (b) production of biofertiliser (c) organic solid waste management through vermitech, (d) reclamation of sodic soils through vermitech and (e) scaling up.

  1. a) Culturing of earthworms (epigeic and anecic varieties)

Earthworm cultures of anecic variety (Lampito mauritii) and epigeic variety (Perionyx excavatus) were established in cement tanks containing sodic soil (pH 9.5-10). These culture units served as the stock of the above mentioned earthworm species.

  1. b) Production of biofertilizer (Vermicompost and Vermiwash)

Vermiwash is a leachate of earthworm-worked organic matter, soil and vermicompost containing available form of nutrients NPK, mucus and coelomic secretions. Three such units were set up with a production capacity of 7 litres per day.

Wooden boxes (380 mm x 190 mm x 190 mm each) were inoculated with earthworms as per the vermitech pattern in sodic and non-sodic soils. Of these, 9 boxes were filled with soil of pH 8.5 to 9.5, and the remaining 14 boxes were filled with sodic soil of pH 9 to 10.  5 earthworms of the epigeic Perionyx excavatus or the anecic Lampito mauritii or a combination of both Perionyx excavatus and Lampito mauritii (5 + 5) were incoluated into the soil.

  1. c) Organic solid waste management through vermitech: Ten new vermicomposting units, each 2m x 1m x 1m in sodic soils, were started to recycle farm waste. These also served as demonstration units with production capacity of about 350 to 500 kg of vermicompost per pit per harvest.
  2. d) Reclamation of sodic soils applying vermitech

Experiments were conducted on Shivri farm of UPBSN, about 25 km from Lucknow city.

Preliminary field experiments (plot size 12 m x 3 m) in sodic soil (pH 9.5) were started in Sept 1996. Earthworms were first inoculated using vermitech bioremediation technique with organic matter (straw and sawdust) @ 5 tonnes/ha. This plot was divided into sub plots of equal size for conducting trials on vegetables like tomato and onion. Tomato yield was 27.77 tonnes / ha and Onion yield was 1.28 tonnes / ha.

Two trials wee conducted to study the impact on soil properties and crop productivity. In the first trial, this technique was used on 9 plots (wheat/paddy) each with an area of 6m x 6m. Three treatments were used: (1) A combination of Vermiwash treatment, Green manuring and Mulching [VWGM], (2) A combination of VWGM and Earthworm inoculation [VWGME]and (3) A combination of VWGM, Earthworm inoculation and Vermicompost [VWGMEVC].

Of all, the third treatment, i.e., a combination of VWGM, Earthworm inoculation and Vermicompost [VWGMEVC], gave the best results. In this treatment, the soil pH reduced by 5 percent while the soil organic carbon increased by 177 percent. The yield was also highest under this treatment, with paddy yielding 2960 kg/ha and wheat with 1650 kg/ha.

The second trial was conducted on vegetables like Spinach / Onion / Potato on 9 plots measuring  3m x 3m each. The treatments tried out were (1) Vermicompost @ 6 tonnes / ha  [VC], (2) Vermiwash with 1: 10 dilution [VW] and (3) a combination of both [VCVW]

Of all, the third treatment, i.e., a combination of VC and VW, gave the best results. In this treatment, the soil pH reduced by 7.8 percent while the soil organic carbon and available phosphates increased by 117 percent. The yield was also highest under this treatment- Spinach with 5.08 tons/ha, onion with 6.28 tons/ha and potato with 11.67 tons/ha

Scaling up: Extension of vermiculture in project districts of UPBSN.

The concept of vermitech (vermiculture, vermiwash and vermicomposting) was disseminated in several districts in UP. Trainings on vermiculture were also conducted for the farmers, NGO workers and staff of UPBSN. Farmers of neighbouring villages were encouraged to practice organic farming by using various bio-fertilizers. Based on impact, farmers tried various combinations of bio-fertilizers.

Conclusion

There has been a remarkable change in the soil structure. An eco-friendly approach with application of compost and earthworm management in the Vermitech pattern is more suitable more long-term bio-remedial benefits of difficult soils such as sodic soil than chemical treatment of the same through gypsum and such methods.

Acknowledgement

Thanks are recorded especially to Shri D K Mittal, I.A.S, the former MD of UPLDC and to all the Authorities and Staff of the Uttar Pradesh Land Development Corporation (Uttar Pradesh Bhumi Sudhar Nigam Ltd) and to The New College, Chennai. To the field staff of the project, a host of farmers and people of several villages of UP who extended all their cooperation to make this a successful project we are all indeed grateful.

Sultan Ahmed Ismail, Sundaravadivel, S., Jagan Mohan Reddy, Geetha, K.S. & Abdullah Adil Ansari, Ecoscience Research Foundation, 98, Baaz Nagar, 3/621 East Coast Road, Palavakkam, Chennai 600041, INDIA

Sultan Ahmed Ismail, Sundaravadivel, S., Jagan Mohan Reddy, Geetha, K.S. & Abdullah Adil Ansari

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