RESEARCH ARTICLE CURRENT SCIENCE, VOL. 108, NO. 8, 25 APRIL 2015 1501 *For correspondence. (e-mail: rajendrahanagar@gmail.com) Status of soil degradation in an irrigated command area in Chikkarasinakere Hobli, Mandya district, Karnataka Rajendra Hegde 1, *, A. Natarajan 1 , R. S. Meena 2 , K. V. Niranjana 1 , S. Thayalan 1 and S. K. Singh 3 1 National Bureau of Soil Survey and Land Use Planning (ICAR), Hebbal, Bengaluru 560 024, India 2 National Bureau of Soil Survey and Land Use Planning (ICAR), Udaipur, Rajastan 313 001, India 3 National Bureau of Soil Survey and Land Use Planning (ICAR), Amravathi Road, Nagpur 440 033, India Of late, the crop productivity levels in many irrigated command areas have plateaued or started declining rapidly due to the deterioration of soil health. Unsci- entific 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 Chik- karasinakere 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 irriga- tion was introduced during 1930s. The process of degradation will accelerate if appropriate interven- tions/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. IRRIGATION is an age-old art and is believed to be as old as the history of agriculture itself. References to wells and tanks are found in several ancient scriptures of the world and their important role in irrigation has also been highlighted. References could be quoted to attest that adverse effects of excess water use even from ancient times. According to a hymn in the Narada-Smirthy, a Hindu epic, Sage Narada said, ‘No grain is ever produced without water, but too much water tends to spoil the grain. An inundation is as injurious to growth as is the dearth of water’. It is a well established fact that continuous use of land for irrigated crop production increases the groundwater level and consequently the salinity levels in the soil. Over a period of time, if there is inadequate drainage, the depth to the water table will decrease and a shallow saline water table develops, particularly in semi-arid tropics. In the presence of a shallow saline water table, crop production can suffer when salts accumulate in the surface soil through capillary action and/or directly as a result of waterlogging. The twin menace of waterlogging and soil salinization/sodification has threatened the sustainability of irrigated agriculture for centuries. Historical records have revealed that many ancient civilizations that relied upon irrigated agriculture have failed due to these pro- blems. The Sumerian civilization of ancient Mesopotamia declined as agricultural productivity began to decrease due to waterlogging and soil salinization 1 . The same process that contributed to the demise of ancient civiliza- tions continues to plague irrigated areas today. A two- decade-old estimate suggests that worldwide crop production losses associated with salinity on irrigated lands are around US$ 11 billion annually and are increas- ing every year 2 . The green revolution, witnessed during the 1960s and 1970s in India, was a great success mainly due to the introduction of high-yielding variety seeds coupled with subsidies and such other promotional incentives on crucial inputs like irrigation, fertilizer, pesticides and a policy support system. There is no doubt that these meas- ures really helped India achieve self-sufficiency in food grain production. Subsidies on inputs and output price support motivated the farmers to adopt new technologies. But prolonging those policies in the post-green revolution period resulted in distortion of farm-level incentives for