Current Science

Rajendra Hegde ¹, A. Natarajan ¹, R. S. Meena ², K. V. Niranjana ¹, S. Thayalan ¹, S. K. Singh ³

Affiliations
1 National Bureau of Soil Survey and Land Use Planning (ICAR), Hebbal, Bengaluru 560 024, IN
2 National Bureau of Soil Survey and Land Use Planning (ICAR), Udaipur, Rajastan 313 001, IN
3 National Bureau of Soil Survey and Land Use Planning (ICAR), Amravathi Road, Nagpur 440 033, IN

Abstract

Of late, the crop productivity levels in many irrigated command areas have plateaued or started declining rapidly due to the deterioration of soil health. Unscientific and excessive irrigation, growing crops not compatible with the soils and unscientific management of soils are the main causes for the present situation. Waterlogging, increased salinity/sodicity, nutrient imbalance, shrinking diversity of micro-flora and fauna have become major constraints limiting the choice of crop and crop productivity. We present a study on this issue from the Cauvery command area. Detailed cadastral-level survey taken up to study the status of soil and other resources occurring in Chikkarasinakere block of Mandya district, Karnataka during 2010 has brought out the alarming state of land degradation observed in the area. Nearly 59% of the area is suffering from various degrees of chemical and physical degradation. The situation becomes alarming because the area had well-drained red soils highly suitable for irrigated agriculture when irrigation was introduced during 1930s. The process of degradation will accelerate if appropriate interventions/investments are not undertaken on priority. Continuation of present management practices can rapidly damage the soil health. As the command area is one of the important rice bowls of Karnataka, there is an urgent need to reverse the process of degradation by adopting site-specific interventions as indicated in the study. The present study reveals that the Cauvery command are in Karnataka is losing Rs 1000 crores every year due to this problem.

Keywords

Crop Productivity, Irrigated Command Area, Nutrient Imbalance, Land Degradation, Soil Salinity/Alkalinity.

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K. Rajan ¹, A. Natarajan ², V. Kasthuri Thilagam ¹, K. S. Anil Kumar ², D. Dinesh ¹, N. M. Alam ³, O. P. S. Khola ¹, R. C. Gowda ⁴

Affiliations
1 ICAR-Indian Institute of Soil and Water Conservation, Research Centre, Udhagamandalam 643 004, IN
2 ICAR-National Bureau of Soil Survey and Land Use Planning, Hebbal, Bengaluru 560 024, IN
3 ICAR-Indian Institute of Soil and Water Conservation, 218, Kaulagarh Road, Dehradun 248 195, IN
4 Department of Soil Science and Agricultural Chemistry, GKVK, University of Agricultural Sciences, Bengaluru 560 065, IN

Abstract

Effect of sodicity on clay dispersion in salt-affected black soils of the Kabini canal command area in Chamrajnagar district, southern Karnataka was studied. Forty-eight soil samples were collected from nine soil profiles and analysed for physical and chemical properties. The clay dispersion ranged from 0.57% to 62.1%. High positive and negative correlations with exchangeable sodium and exchangeable calcium respectively, with clay dispersion were recorded, which can be predicted better with exchangeable sodium and available soil water. Based on clay dispersion value, 2%, 27% and 71% soils are dispersive, intermediate dispersive and non-dispersive respectively. Based on exchangeable sodium percentage, 50, 21 and 29 soils are dispersive, intermediate dispersive and nondispersive respectively. Application of gypsum and organics reduces the clay dispersion in surface soil. Sub-surface drainage will be more effective. Construction of soil and water conservation structures with pile foundation; providing cement lining for soil stabilization in normal construction; providing drainage lines for the structures; construction after refilling with non-dispersive soil will save the structures in salt-affected soils.

Keywords

Clay Dispersion, Sodicity, Sub-Surface Effect, Surface Effect.

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