The solution for providing food security to the world without affecting ecological balance lies in the adoption of new scientific tools available, particularly the use of vital inputs from space remote sensing and bio-technological advances. While India and China have built an impressive capability in space technology by developing their own launch vehicles, communication and remote sensing satellites and application programmes, other countries in Asia have also successfully used space imageries available from International satellites for monitoring and management of their natural resources through cooperative arrangements. India for example, has effectively used its own IRS series of remote sensing satellites to establish and continuously monitor its national forest inventory and to prevent further encroachment of its forest wealth. Extensive use of satellite imageries for mapping soil characteristics, land-use in terms of single crop, double crop, fallow and residual land areas, meteorological parameters and water resources have led to the identification of agro-climatically coherent regions having homogeneous characteristics such as slope, soil depth, texture and water holding capacity, which are vital for developing locale specific and agro-climatically suitable cropping patterns. The ability to identify saline/alkaline soils at micro levels using space imageries have enabled the application of suitable measures to reduce soil salinity and adoption of alternate crops or cropping patterns to restore the fertility of the land to the original level. Country wide mapping of wasteland at micro-level has been able to identify 54 million ha. of wasteland (Fig. 11), about half of which can be reclaimed for productive agricultural usage with appropriate corrective actions (Rao 1995a; 1995c).

Repetitive coverage provided by satellites has been widely used for mapping the temporal changes in water bodies and reservoirs in addition to providing a reliable estimate of water storage in the reservoirs thereby facilitating optimal scheduling of irrigation. A classic example is the country wide hydrogeomorphological mapping from space showing ground water prospect areas which has improved the rate of success of finding underground water to 92 per cent compared to 45 per cent achieved using purely conventional methods. Models based on the area extent of seasonal snow fall have been developed to predict snow-melt runoff into the reservoirs. Identification of waterlogged pockets in the command areas of irrigation projects and inventory of crop lands and cropping patterns have facilitated efficient water use, thereby increasing the cropping intensity. Remote sensing data are being extensively used to predict the acreage and yield of all major crops and also to identify degraded watersheds for initiating appropriate conservation measures for soil and water (Rao 1995c). Space imageries have fully established their ability for substantially improving the marine fish catch by identifying areas of rich fish shoals based on ocean temperatures and phyto-plankton density measurements.

Doubling or in some cases tripling of food grain productivity is required to meet the basic minimal requirements of the projected population growth in many of the developing countries in Asia, Africa and Latin America. Even though the global cultivable land area can in principle be increased from the present 1500 million ha. to about 2150 million ha. through reclamation of culturable wasteland, the prospect of such increase is limited to less than 10 per cent, or about 60 million ha. over the presently cultivated crop land of 820 million ha. in Asian continent. Historically, it is recognised that increase in the area of cultivation in the recent past has in fact only contributed to less than 10 per cent increase in the food grain output. Even with the possible reclamation of about 25 million ha. of wasteland and exploitation of the full irrigation potential by doubling the presently irrigated area of 40 million ha., the annual food grain output in India can at best be increased to 250 million tons as against the requirement of 450 million tons by 2050. Analysis by the world bank and FAO have clearly pointed out that countries like India and China cannot support beyond 1.5 times their present population (FIAO 1988; Murai et al. 1990) using the present agricultural technology.

The challenge of providing adequate food security to the growing population can only be solved by achieving substantially higher yields through initiation of sustainable integrated development strategies. Significant advances in biotechnology have resulted in a variety of new genetic breeds, early maturing dwarf varieties of crops, pest resistant hybrid varieties and suitable cultivation strategies. Combined with integrated pest management strategy, use of bio-pesticides and conservation of top soil and water resources, these bio-technological advances have led to a substantial increase in the genetic potential up to 8–10 ton/ha. under controlled conditions, which implies that achieving an average yield of 4–5 ton/ha even in field conditions is well within our technological capability. Practical realisation on nationwide scales however must take into account the boundary conditions imposed by ecological, environmental, social and cultural factors in each country to ensure long term sustainability. This requires a clear understanding of land capability, continuous monitoring and optimal management of natural resources, and use appropriate agricultural practices.

Sustainable development of natural resources is obviously dependent on maintaining the fragile balance between productivity functions and conservation practices through monitoring and identification of problem areas requiring application of energy intensive agricultural practices, crop rotation, bio-fertilisers and reclamation of underutilised lands.²⁴ It calls for the integration of various renewable and non-renewable resources, characterisation of coherent zones of agricultural identities and identification of physical constraints as well as ecological problems at the micro-level of each watershed. Combining space derived vital inputs on soil characteristics, agricultural practices, underground and surface water resources, forest cover, environmental status and meteorological information with collateral data on socio-economic factors it is possible to subdivide each watershed into 400–500 micro-level homogeneous units for identifying suitable conservation measures and appropriate bio-technological practices to significantly enhance the production on a sustainable basis (Fig 12). In the few selected watersheds where sustainable integrated development strategy has been implemented, as in the cases of drought prone districts of Anantapur and Ahmednagar in India, two healthy crops are now grown and the water table has gone up by almost 3–5 meters in the last three years as against non-availability of even drinking water in summer months (Rao 1995a; Rao, Chandrasekhar and Jayaraman 1995).