Irrigation Induced Land Degradation in Godavari Command of Semi-Arid Agro-Eco-Region

摘要

An assessment of land degradation was carried out in the right bank of Godavari command representing semi-arid agro-eco-region of central India. The soils were high in clay (45.5 to 74.8%), low in hydraulic conductivity (0.04 to 1.50 cm h"1) with meanweight diameter between 0.24 to 0.68 mm. The physical properties of soils were more deteriorated in the subsoil horizons of lowlands in the tail region. The ESP varied from 7.3 to 20.4 and was relatively low (< 10%) in the upland and increased in lowland. The electrical conductivity (ECe) of saturation extract varied from 0.47 to 8.03 dS nr1 and increased down the depth. As per the U.S. Soil Salinity Laboratory criteria 19.0% soils were found to be degraded out of which 12.5% were saline and 6.5% saline-sodic. However, as per the modified criteria proposed the soils on 79.2% area were sodic and 18.9% as saline-sodic which were further subdivided into slightly sodic (56.5%), moderately sodic (22.7%), moderately saline-sodic (12.4%) and strongly saline-sodic (6.5%). The yield of sugarcane and wheat were negatively correlated with ESP and ECe. The soils pose the problem of internal drainage and short term water logging in lowland. An ESP of more than 10 and exchangeable Ca/Mg ratio of less than 1.5 aggravated the condition and were associated with constraints which were detrimental for crop production.