Impact of Tank Silt on Soil Fertility-A Study in Mysuru District

A de-silting programme of Dorekere tank was undertaken in Piriyapatna taluk of Mysuru district in 2012–13. This study was undertaken in 2014 to assess the impact of de-silting on the tank and of silt application on the farmers’ fields. A total of 32 soil samples were analyzed of which one was control and 6 were from the tank bed. The remaining 25 samples were drawn from fields of farmers who had applied silt in the year 2012–13. Tank silt had average 68%, 25% and 7% silt, clay and sand, respectively. Application of silt to farm lands had increased the silt content from 45% to 49% whereas clay and sand contents had reduced marginally from 30% to 29%, and from 25% to 22%, respectively, leading to improved soil porosity and moisture holding capacity. The average pH of soils applied with silt was 7.27, with 0.17 ds/m EC and 0.49% OC, indicating no significant impact on soil physical parameters. The analysis also revealed there was no reduction in the quantity of fertilizers used by farmers. However, the major crop tobacco showed better vegetative growth, though the curing issues reduced income from tobacco. There was 20 to 25% higher yield of finger millet and dolichos apart from more fodder yields and increased revenues. Tank rehabilitation, thus, had improved the tank storage capacity, crop yields and revenues. Building farmers’ awareness about the method of silt application and soil test-based nutrient application would ensure better results for further improving soil fertility and sustainability of farming.