Basic Information | International Commission on Irrigation & Drainage (ICID)

IMPROVING SOIL MOISTURE

Soil Moisture is a key factor that impacts on the productivity of the soil. Three main factors affect soil moisture content:

How well the soil can absorb water;
How well the soil can store moisture; and
How quickly the water is lost or used.

Soils can have poor infiltration if the soil aggregates have broken down and the spaces between them are small (degraded soil structure). This can be due to (i) compaction, (ii) continued cultivation, (iii) declining soil organic matter; and (iv) surface crusting due to sodic clay soil.

The two main sources of moisture loss are drainage and evaporation. A soil which has been saturated and then allowed to drain for 24 hrs is said to be at Field Capacity.. Soil management that improves soil structure or organic matter should gradually improve moisture storage.Improving soil organic matter will reduce drainagelosses by improving Field Capacity and will also reducethe loss of important mineralsdue to leaching.A ground cover of mulch or low growing plantscan reduce evaporation from the top soil as well asproviding protection against erosion. Similarly wind breaks reduce evaporation losses and retain soil moisture upto 100 metres away.