Irrigation impacts on the chemistry of soils in the study area
Keywords:
Soluble cations and anions,, sodium absorption ratio (SAR), exchangeable, sodium percentage (ESP), boron toxicity.Abstract
Irrigation plays an important role in the present agriculture scenario. It is a major source which helps
millions of rural poor in the world to earn their livelihood. Unplanned and unscientific use of both water and
soil resources have led to severe deterioration. As a result of this, a greater threat is being posed to social,
economic and political stability of many developing countries including India. Introduction of large scale
irrigation, excess use of chemical fertilizers and pesticides, deforestation and over grazing, leads to
accelerated soil degradation. In view of this, Sangamner area of Ahmednagar district, India is selected to
study the impact of irrigation on the chemistry of soils. The soil samples were collected from 62 locations
covering the entire study area. The samples were analyzed for PH, EC, Ca2+, Mg2+, Na+
, K+
, Cl-
, HCO3
-
, and
SO4
2-
from saturation extract. The exchangable cations like Na+
, K+
, Ca2+ and Mg2+ were determined by
neutral ammonium acetate extract. pH ranged from 8 to 9.7 reflecting alkaline nature of soils. Higher EC in
the downstream part reflects low flushing rate and sluggish groundwater movement in the area. The
concentration of soluble cations are in the order Na+
>Ca2+>Mg 2+>K+
, whereas Clis predominant followed
by SO4
2-
and HCO3
-
in the soluble anions. Out of the total exchangeable cations, Ca2+ is dominating over the
rest of the cations. Salinisation, sodiumization, waterlogging, nitrate pollution and boron toxicity have been
identified as the possible impacts of irrigation on the chemistry of soils in the area. The soils from the study
area are easily waterlogged during the rainy season. The problem is further aggravated due to decrease in
depth of water table by injudicious irrigation and canal seepage. There is an urgent need to focus attention
on the protection of soils particularly in the irrigation sector. Frequent awareness and training programs for
farmers can be arranged to avoid further degradation of soils.
