A methodology comprising  formulation, validation and use of  integrated hydrologic-agronomic –economic planning  model  to answer questions relating to  crop , land and water resource management  in  alkali reclamation  was established  and applied to alkali watersheds  under rehabilitation .

Of various kinds of salinities, soil alkalinity is a major problem in Indo- Gangetic plains, which has adversely affected the productivity of several million hectares. The externalities of alkalinity are: reduced water infiltration, polluted surface runoff and increased flood hazards which significantly alter the surface and groundwater hydrology and impact the water quality. An in-depth understanding of hydrologic behavior and its implications on choice of technological interventions and environment are very important for land and water use planning.

 

 

In hydrological sense, the reclamation of alkali soils is a continuous process spread over a long period (about 20 years) of time. During the transient stages of reclamation, the irrigation requirements, groundwater recharge and crop-water-production relationships change with time, and so do the optimal mix of crop and irrigation activities .The continuous improvement in groundwater recharge from rain water detained in crop lands (rice paddies) increases groundwater availability and reduces stress in aquifers.

Using the synergy of plant salt tolerance (growing high yielding salt tolerant crop variety) with reduced dose of chemical amendment (hydro-chemical technology) offers greater scope for not only reducing the cost of reclamation but also provides a more environmental friendly solution. But it delays the process of soil improvement. The soil continues to have higher pH and lower infiltration rates for longer period of time and consequently the progress in groundwater recharge is retarded.

There is drastic reduction in surface runoff and sediment loads and thus problem of floods from monsoon rains as well as runoff quality are minimized

The salts from surface flushing and pollution of ground water bodies from salts leached from the root zone during the process of reclamation do not impact environmental sustainability because the  quantity of salt whether flushed or leached from the soil system is very small.  It gets distributed in the large surface and groundwater bodies. The only environmental sustainability concern arises from ground water quality with sodicity and high fluorine concentrations in certain pockets. Technological options to take care of these factors are available, though it would add to cost of reclamation by way of increased doses of chemical amendments

The established relationships between alkalinity (in terms of soil pH) and crop yields indicate a continuously increasing productivity at rates which exceed the rates of increase in cost of production.  So the profitability of alkali land reclamation increases with time and the enterprise was bankable.