Sahyadri E-News : Issue LXXVIII (78)
Ecosystem Restoration for Water & Food Security
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Traditional desilting of lakes-Today's scenarioCite

M A Khan
Principal, K K English School, Varthur

Bangalore has the distinction of the title "CITY OF LAKES". About 4 decades ago, this was very true, and records show that there were more than 800 lakes. A majority of these lakes were freshwater lakes, rain-fed. At the same time, the whole of rural Bangalore was a full agriculture region, where in the farmers used only compost and silt which is rich in NPK from the lakes. Silt was abundantly available in summer season when the lakes would dry up.

Today hardly a few lakes are surviving and a majority of them are highly polluted with effluents and fecal matter generated from sewage. Unplanned urbanization has led to creation of huge sewage sinks- the lakes.

Varthur has the second largest lake of Bangalore which was pristine till 1980. It started to pollute since then as untreated sewage was allowed to flow. It was the efforts of Dr.T.V.Ramachandra that the lake is being desilted and rejunavated now. When the desilting started, there was no farmer surrounding the lake area who was ready to use the highly composted silt as manure. There were rumours spread that it was highly toxic. At this point, T V Ramachandra' s team collected silt sample from the lake at various locations and analyes the silt for nutrient and heavy metal content. The analyses revealed that the silt has rich nutrients (N and P) and did not have any heavy metals. After ascertaining non-toxic aspects of silt, we organized a stakeholder meeting at the school. Queries and apprehensions of the farmers were addressed by IISc team and finally, farmers of the region wholeheartedly decided to get the silt for their agricultural land. After the first crop was grown, IISc team carried out socio economic survey of framers who had used the lake silt to grow vegetables, etc. The study reveals on an average, each farmer has earned Rs 1,50,000 per acre of additional revenue due to higher yield and less burden (of buying synthetic fertilizer)

At this point of time, we took two truckloads of silt for our school garden. We used it to grow tomatoes, brinjal, beans, papaya, drumstick and a variety of greens. The result was mind blowing. Papaya yield was twice the normal, greens were very tasty, all the vegetable yield had grown three times higher than usual.








The most important point was the yield of drum sticks. We usually used to get about 10 to 15 drumsticks, but after using the silt the yield was more than 80 drumsticks. This is when I realized the value of the silt and its richness in NPK.

Two of our school alumni, Mr. Yellesha and Mr. Venkatesh who are agriculturists, witnessed our experiment and closely followed. Mr.Venkatesh used the silt for dry farming and his ragi crop was a bumper crop. Mr.Yellesha used the silt for growing carrots, radish, pumpkins and greens. He also has a bumper crop and both of them are using the silt continuously.

After watching the success of the farmers, now many of them have come forward to take the silt. Till date the BDA (Bangalore Development Authority) has agreed to supply the silt free for farmers up to 15 kms from Varthur lake.

The use of this compost by farmers has drastically reduced the chemical fertilizer used and has conserved soil.

Traditional methods still hold water in the modern technological and scientific advancements.

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