Mapping of biophysical constraints of soils in semi-arid northern transition zone of India by GIS techniques.

The present study was untaken in order to identify and map soil biophysical constraints by GIS techniques in Singhanhalli-Bogur microwatershed in northern transition zone of Karnataka. Ten biophysical soil parameter including depth, coarse fragment/stoniness, texture, structure, tillage pan, rooting condition, surface crust, organic matter, biological activity and sodicity were assessed and interpreted for soil health. The depth of the soils varied from shallow to deep and structure varied from weak to strong with some mapping units showing slightly developed tillage pans. The texture of soils varied from sandy loam to sandy clay, sandy clay loam and clay while the content of coarse fragments ranged from common to many and abundant. Soils having sandy loam texture showed high content of coarse fragments. No signs of unrestricted root developments were observed as the rooting condition was good. The organic matter content of soils ranged from low to high with presence of few to many termite holes indicating biological activity. Physical soil crusts ranging from slight to severe were observed in some mapping units. The soils were free of high sodium concentrations and hence, classified as non-sodic soils. Overall, soil health status varied from poor to medium with the level of constraints ranging from moderate to severe. Soils with severe constraints showed poor health status while soils with moderate constraints showed medium health status.

Land Degradation Mapping in Singhanhalli-Bogur Micro-watershed in Northern Transition Zone of Karnataka through Remote Sensing and GIS Techniques.

The study was undertaken to identify and map areas affected by various land degradation through remote sensing and GIS techniques. The study revealed that the major process of land degradation is water erosion. Three types of water erosion, namely sheet, rill and gully erosion were prevalent in different land forms. Sheet erosion accounted for 77.2 %, rill erosion 6.7 % and gully erosion 16.2 % of the study area. The lowlands, majority of which area was under agriculture land use, was observed to be sheet eroded with severity ranging from slight to severe which was attributed t o overcutting of vegetation, overgrazing and agricultural activities. Rill erosion was prevalent in undulating midlands under agriculture and open scrub land uses, whereas gully erosion occurred in agriculture and open scrub lands. The moderately degraded lands were observed in all land uses but they were more prominent in agriculture lands on moderate slopes. The severely degraded lands were observed on moderate-to-steep slopes in undulating midlands and uplands. The adoption of soil and water conservation measures was recommended for improve soil productivity and sustaining agricultural production at higher levels. In addition, watershed programmes should be undertaken considering the summarized priority for land treatment.

Soil Erosion Mapping in Singhanhalli-Bogur Microwatershed in Northern Transition Zone of Karnataka Using Universal Soil Loss Equation and Geographic Information Systems.

Soil erosion which occurs at spatially varying rates is a widespread threat to sustainable resource management at watershed scale. Thus estimation of soil loss and identification of critical area for implementation of best management practices is central to a successful soil conservation programme. The present study was conducted to assess soil erosion using USLE and suggests possible intervention strategies to address soil loss in Singhanhalli-Bogur Microwatershed of Dharwad District in northern transition zone of Karnataka. The average annual soil loss was 27 tons ha-1yr-1. About 574 ha of the study area was under slight erosion, 118 ha under moderate erosion and 53 ha under severe erosion. The soil loss under different land uses ranged from 7 tons ha-1yr-1 under forest to 40 tons ha-1yr-1 under agriculture. The soil loss under plantation and open scrub land uses were 8 and 26 tons ha-1yr-1 respectively. Major causes of soil erosion were cultivation without proper soil and water conservation measures in area not suitable for crops, denuded areas without vegetation, cultivated fallow on moderate slopes, degraded forests/pastures on steep slopes and poorly managed forest cover. Appropriate soil conservation and land management techniques for the different soil erosion classes were suggested.