Thar Desert in a Flux Dr. R. P. Dhir Ex Director, Central Arid Zone Research Institute -Indian Council of Agriculture research, Jodhpur, Rajasthan, India

Thar Desert in India distinguishes amongst world arid zones by its long history of human settlement and land use, relatively dense human and livestock pressure and a high incidence of cropping, made possible by well evolved traditional management systems comprising mixed farming, agro-forestry, mixed cropping with well adapted crops. However, droughts of various intensities have been a part of climate causing immense human suffering and loss of livestock. However, the past few decades post-independence era has seen huge multi-dimensional development effort, albeit with accentuated degradation of some of the natural assets.

Fears that the Thar Desert was expanding north-west wards, the earliest technological focus was on identification of suitable plant species for greening and development of technique for stabilization of sand dunes. Following their success, new areas of research such as characterization and mapping of natural resources, pasture land rehabilitation, human factor studies and crop and animal husbandry researches. These were supplemented by emphasis on rainfed horticulture, technology transfer and solar energy and presently by high-tech approaches. However, by far the biggest approaches have been in the area of irrigation development made possible by rural electrification-tube well technology and diversion of Himalayan river water through a ~850 km long lined canal and with water lift system at places. As a result presently one- third of all cropped area in the Thar is irrigated and it accounts for more than 70 % of the value of the crop produce. Grondwater sourced irrigated areas and to an extent canal command area make use of pressure irrigation systems.

The degradation due to wind erosion has come down because of tree plantation and sand dune stabilization, more so in the canal command area, but also due to as yet an unexplained slowdown of wind regime in the region as whole. However, despite a sound regeneration and grazing norm technology, the open use grazing lands that constitute ~25% 0f the arid zone remain in a highly degraded form. Water-logging and secondary soil salinization problem in canal command area has come under control, partly by reducing canal water supplies, de-watering.

The irrigated are being cropped increasingly by cotton, groundnut, condiments and spices and recent successes are in high value crops like the pomegranate and date palm cultivation with exploration in hi-tech areas.